Good Calories, Bad Calories: A Critical Review; Chapter 8 – The Science of the Carbohydrate Hypothesis

coverIntroduction

This is another post in my ongoing series of posts on Gary Taubes’s Good Calories, Bad Calories (GCBC). Several of the publications that Taubes cites for various claims are amazingly obscure. I’m working on getting a couple of them right now, so perhaps this post will be updated in the future when I receive and look through them. In the meantime this post is the fact-checking I have done of chapter eight so far.

Surprisingly it doesn’t contain that much “science of the carbohydrate hypothesis.” It’s really more of an introduction to the similarly-named chapters toward the end of the book. He spends some time with Tokelau (which I will get to soon), discusses what homeostasis is, and then reworks one of his earlier articles about salt toward the end of the chapter.

Not the Introduction

God, I love the beach. I bet it's paradise over there.

Ian Prior in Tokelau, 1971

For the first several pages of chapter eight Taubes discusses a rather interesting cohort study involving the people of the Tokelau Islands in the south pacific. Briefly, Ian Prior, an epidemiologist from New Zealand, decided to study the residents of Tokelau while the New Zealand government wanted to organize a large voluntary migration effort of the peoples from the islands to NZ. Some opted to stay on the Tokelau Islands rather than migrate, which provided Prior an excellent opportunity to study the two populations and compare their lifestyles, diet, and health. As you might guess, the islanders that “immigrated” to NZ ended up having more health problems than those that stayed behind.

Why? What happened? According to the University of Minnesota synopsis of the study, it is due to “the tendency for migrants at all ages to be heavier than non-migrants. Migrants had more diabetes and smoked more, drank more alcohol, and exercised less.1 These factors make the poorer health among the migrants pretty easy to explain. Taubes, however, doesn’t want you to think that any of this has to do with the study results so he straight-up lies to you on page 138:

A number of factors combined to make this higher disease incidence among the migrants difficult to explain. For one thing, the Tokelauans who emigrated smoked fewer cigarettes than those who remained on the atolls, so tobacco was unlikely to explain this pattern of disease.

He goes on to state that the migrants were far more physically active and had a much more “rigorous” lifestyle than the non-migrants because they worked in sewing factories and had to walk to shops. I’m not even kidding. Again, this directly contradicts the actual study results.

So how does Taubes explain the health discrepancy? Why, it’s exclusively due to saturated fat intake, of course! Yes, as it turns out the native diet of the Tokelauans ate a diet largely composed of fish, coconuts, and fruit. According to Taubes it was the coconut oil in the Tokelauan diet that was apparently uniquely protective because coconut oil has saturated fats. Moreover, Taubes also mentions that the migrants to NZ started eating bread and potatoes which contributed to their health problems. And, of course, he has to drag Keys into this saying “If Keys’s hypothesis was correct, the migrants should have manifested less evidence of heart disease, not more.”

Actually, no. The non-migrants should have manifested less heart disease. Taubes is conflating the fatty acids in coconuts with all saturated fatty acids. The fatty acids in coconuts are quite a bit different from that fatty acids found in the foods that Taubes promotes throughout the book (beef tallow, bacon, cheese, etc.) It has been demonstrated to the satisfaction of most people that coconut oil does not have a huge impact on serum cholesterol levels and by extension heart disease. Matter of fact, the first person to demonstrate this was none other than Ancel “Beelzebub” Keys himself!2,3

Aside from alcohol consumption, diet was not even mentioned in the study synopsis as being a potential factor in the health decline. Nevertheless, Taubes credits the saturated coconut oil for the good health of the non-migrants, and blames the bread and potatoes on the poor health of the migrants. What Taubes glosses over are other dietary components introduced to the migrants which include salt, eggs, dairy, and red meats.4

* * *

One of the main goals of GCBC is to upend everything we all thought we knew about nutrition: Saturated fats from animals are actually good for you! Carbohydrates from fruits, vegetables, or grains are actually the enemy! Calories don’t matter! You can gorge yourself of whatever you like, and as long as it doesn’t include carbohydrates you’re in the clear! Dietary fiber is meaningless! I suspect Taubes does this not because these things are true or even that he believes these things are true, but rather because it sells more books. It’s a shame people have to get wildly inaccurate information about how to take charge of their own health for the financial gain of one individual, but that seems to be the case.

Another one of these bits of “conventional wisdom” that he upends is the idea that salt has anything to do with high blood pressure. Page 146:

[P]ublic-health authorities for the past thirty years have insisted that salt is the dietary cause of hypertension and the increase in blood pressure that accompanies aging. […] That’s the hypothesis. But in fact it has always been remarkably difficult to generate any reasonably unambiguous evidence that it’s correct.

He goes on to state that even if by some miracle salt really does somehow influence blood pressure, it has such a negligible effect that cutting salt intake “makes little difference” to our overall health. As evidence he cites a 2004 Cochrane Review by He and MacGregor. Old versions of Cochrane reviews are difficult to find. It seems they usually replace the old ones every time the data gets updated. In this case I was only able to find the 2013 version of the same title by He and MacGregor.5 Let me quote from the end of the review (emphasis mine):

Our meta-analysis of randomised trials of longer-term modest reductions in salt intake demonstrates a significant effect on blood pressure in individuals with both elevated and normal blood pressure. The blood pressure fell, on average, by 5/3 mmHg in hypertensives and 2/1 mmHg in normotensives. These falls in blood pressure would have an immediate and significant impact on population blood pressure and would, therefore, be predicted to reduce stroke deaths by approximately 14% and ischaemic heart disease (IHD) deaths by 9% in individuals with elevated blood pressure, and in individuals with normal blood pressure reduce stroke and IHD deaths by approximately 6% and 4% respectively. It is important to note that these reductions in stroke and IHD deaths were estimated from a previous meta-analysis of prospective observational studies. A recent meta-analysis of 1 million adults in 61 prospective studies demonstrates that the relationship between blood pressure and cardiovascular risk is much stronger than previously estimated. Therefore, the reductions in stroke and IHD with the modest reductions in salt intake might be even greater. Since raised blood pressure is also a major risk factor for heart failure, a reduction in salt intake would likely reduce the incidence of heart failure.

I’ll leave it up to you if you think if a modest reduction in salt intake in fact “makes little difference.”6

* * *

Taubes tries to make the case that CHOs are the real culprit leading to insulin resistance which leads to hypertension and ultimately atheroslcerosis. Page 150 of the hardback Taubes states:

Finally, by the mid-1990s, diabetes textbooks, such as Joslin’s Diabetes Mellitus, contemplated the likelihood that chronically elevated levels of insulin were “the major pathogenetic defect initiating the hypertensive process” in patients with Type 2 diabetes. But such speculations rarely extended to the potential implications for the nondiabetic public.

Taubes is quoting out of context here. The actual quote states7:

Should hyperinsulinemia be the major pathogenetic defect in initiating the hypertensive process in patients with NIDDM, it is unlikely that it sustains the hypertension indefinitely. With increasing insulin resistance, the pancreas must secrete higher levels of insulin. Eventually, its reserve capacity is exhausted and plasma insulin levels fall. Other mechanisms must then sustain the hypertension.

Interestingly, immediately before the cherry-picked quote from Taubes is a statement that contradicts Taubes’s argument:

[H]ypertension and insulin resistance may be different clinical manifestations of a common underlying cellular defect by which the level of cytosolic free calcium is increased and the level of intracellular free magnesium is decreased.

As a matter of fact the entire paper makes the argument that the cause of hypertension is clearly multifactorial.

* * *

Page 150:

Though this carbohydrate-induced water retention and the hypertensive effect of insulin were occasionally discussed in nutrition and dietetics textbooks-Modem Nutrition in Health and Disease, for example, which was published in 1951 and was in its fifth edition by the 1970s-they would appear solely in the technical context of water and electrolyte balance (sodium is an electrolyte), whereas the discussion of hypertension prevention would focus exclusively on the salt hypothesis.

Nope. Not even close. Modern Nutrition in Health and Disease describes a variety of factors associated with hypertension. And when it comes to prevention does not “focus exclusively on the salt hypothesis.” Example from the 1999 edition that I have:

In hypertensives whose blood pressures have been controlled with medications, weight loss or NaCl restriction more than doubles the likelihood of maintaining normal blood pressure after withdrawal of drug therapy. The following lifestyle modifications have been recommended as adjunctive or definitive therapy for hypertension: weight reduction if overweight; aerobic exercise; limited NaCl and alcohol intake; maintenance of adequate dietary potassium, calcium, and magnesium intake; smoking cessation and reduced dietary saturated fat and cholesterol intake for overall cardiovascular health.

It’s a shame Taubes never reads what he cites.

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Good Calories, Bad Calories: A Critical Review; Chapter 9 – Triglycerides and the Complications of Cholesterol

cover

Introduction

This is something of an ongoing review, chapter by chapter, of Gary Taubes’s extraordinarily dense book Good Calories, Bad Calories, which I usually shorten to GCBC. You might even consider this more of a fact-checking than a review, but whatever. I’m not going to get into a semantic argument. I wrote my first review of this book back in 2012, but after writing it I felt very unsatisfied. GCBC is such a dense book filled with so many unsubstantiated claims that I felt the book demanded a more thorough review. Other bloggers, like James Krieger at Weightology, seem to feel the same way and have tried to provide such a review only to eventually give up once they realize the gravity of the task. I may also give up at some point. I actually have given up a number of times only to feel compelled to hit at least one more chapter.

If you would like to read other parts of this ongoing review go to the table of contents on my Book Reviews page. FYI: All page numbers in this review refer to the hardback version of the book.

Not the Introduction

Page 158 Taubes discusses a paper1 by Pete Ahrens

By 1957, Ahrens was also warning about the dangers of oversimplifying the diet-heart science: maybe fat and cholesterol caused heart disease, or maybe it was the carbohydrates and triglycerides. “We know of no solid evidence on this point,” wrote Ahrens, “and until the question is further explored we question the wisdom of prescribing low-fat diets for the general population.”

However, that quote is taken out of context. Taubes makes you think Ahrens is saying that there is “no solid evidence” regarding whether or not carbohydrates caused heart disease, but Ahrens is really referring to the ambiguity (at the time) of whether HDL or LDL causes heart disease. Actual quote:

[W]e are tempted to ask whether the lower density lipoproteins are less “atherogenic” than the higher-density lipoproteins rich in cholesterol and phospholipids. We know of no solid evidence on this point […]

I don’t think it’s a big deal, but it is misleading. What is even more misleading, though, is the information that is in the Ahrens paper that was purposefully ignored by Taubes because it runs contrary to his argument.

In this chapter (among other chapters) Taubes tries to make the case that cholesterol is not very relevant in discussions of atherosclerosis. The real culprit, according to Taubes, is triglycerides which are raised by those evil carbohydrates. Triglycerides are the only biomarker that matters. But while the Ahrens paper cited by Taubes does indicate that high CHOs can lead to elevated triglycerides it also makes clear a few other things, like vegetarian diets and very low fat diets are best for reducing lipids (triglycerides and cholesterol) and that plant-based fat is preferable to animal fats in the same regard.

Don’t believe me? Here are a few quotes from the paper:

  • “Experience to date has shown that two regimens are effective in lowering serum lipid levels of our outpatients. The first is total vegetarianism, in which all dairy products are omitted except for skim milk, washed cottage cheese, skim milk cheeses, and egg whites.”
  • “The second regimen consists of a very low fat diet (less than 25 Gm. per day) supplemented by an ounce or more of corn oil at least three times daily.”
  • “Serum lipids can be altered by dietary means, and experimental data lead to the presumptive conclusion that unsaturated fats in the diet cause depressions in levels of cholesterol and phospholipids.”
  • “[P]atients with existent or threatening arteriosclerosis may be justifiably advised to eat higher proportions of unsaturated fats.”

There is even a nice graph in the paper that Taubes would probably prefer you not see.

ahrens

I don’t think it needs any editorializing, but in case you can’t tell ALL of the lipid measurements – triglycerides, phospholipids, free cholesterol, and total cholesterol – are higher when fed animal fats at ALL points compared to plant fats.

* * *

On page 159 Taubes discusses a publication by Kuo2 that Taubes uses to support his carbohydrate-leads-to-hypertriglyceridemia-and-therefore-CHD argument. The study in question does show that his study patients with high levels of serum triglycerides were able to lower them when on a low-CHO diet. However, what is made clear in the study is that this is only true for patients with an abnormal condition of carbohydrate sensitivity, and that a diet with moderate carbs does not lead to hypertriglyceridemia in normal patients. In fact, Kuo mentions that one would need to eat an absurd amount of CHOs to induce elevated triglycerides. From the paper (emphasis mine):

A moderately high dietary sugar and other carbohydrate intake, amounting to 35% to 40% of total daily calories, did not appear to exert a significant effect on the blood lipid levels of young normolipemic subjects with negative family history of coronary disease and abnormality in carbohydrate metabolism. It was necessary to raise the carbohydrate intake to 85% to 90% of total calories to induce hyperglyceridemia in patients who were not abnormally sensitive to carbohydrates.

In the same paragraph in which he mentions the Kuo paper, Taubes claims the CHO-triglyceride-CHD hypothesis was confirmed by two other big studies at the time (Goldstein et al. and Carlson and Bottiger).3,4 Except they don’t even mention the pièce de résistance of Taubes’s argument: the carbohydrates. They simply discuss the association between CHD and triglycerides, which has never been disputed as far as I know. No mention of carbs at all in these papers.

* * *

On page 160 Taubes claims that the US government – and, by extension, researchers – ignored triglycerides as a risk factor for CHD in favor of studying cholesterol because everyone had a huge hard-on for Keys, apparently:

The National Institutes of Health, which was effectively the only source of funding for this research in the United States, had already committed its resources to three enormous studies-the Framingham Heart Study, Keys’s Seven Countries Study, and the pilot programs of the National Diet-Heart Study. These studies would measure only cholesterol and so test only Keys’s hypothesis. No consideration was given to any alternative hypothesis.

I’m sure you’ll be shocked to discover that Taubes is not exactly being honest here. Two out of the three studies that he said measured only cholesterol in fact measured both cholesterol and triglycerides (among other things).5-7 In fact, one of the Framingham papers mentions that triglycerides are a risk factor, albeit not as predictive as cholesterol is (emphasis mine):

The data presented suggest that in men the moderately elevated cholesterol values commonly encountered in the general population, regardless of the metabolic aberration responsible or how it is transported or partitioned among the lipoproteins, are associated with increased risk of coronary heart disease. Elevated endogenous triglyceride values appear significant in coronary atherogenesis only when accompanied by high cholesterol values.

* * *

On pg 160 of hardback Taubes states:

By 1961, Keys and his collaborators in the Seven Countries Study had measured cholesterol in over ten thousand men. By 1963, they had completed the exams on another eighteen hundred men. Even had it been technically possible to include triglycerides in the measurements, or to return to the original locales and retest for triglycerides, the cost would have been astronomical. The result, as we’ve seen, was considered a resounding victory for Keys’s fat-cholesterol hypothesis.

His citation for this is page I-7 in the study program and objectives which is a table of causes of death and a table of death rates from US vital statistics.8 There is no reference for cholesterol or triglycerides or exams or cost or really anything that Taubes claims here.

* * *

On page 161 Taubes discusses a series of papers published in the NEJM that report on various disorders of lipoprotein metabolism….. aaaaaaand makes some claims about them that are not backed up by the evidence in the actual papers (emphasis mine):

Four of the five lipoprotein disorders described in this series were characterized by abnormally elevated levels of triglycerides in the very low density lipoproteins. For this reason, Fredrickson, Levy, and Lees also warned against the dangers of advocating low-fat diets for all patients, because these diets increased carbohydrate consumption and so would elevate triglycerides[…]

As evidence for the claim Taubes cites page 219 of Fredrickson et al. 1967.9 That paper neither advocates for or warns against low-fat diets. In fact it’s never mentioned, but here are a few things that are mentioned in the section on dietary management of this disorder:

  • “[A] patient with a marginal Type II pattern who has neither of the other components of the triad diagnostic for the familial syndrome and who has a high intake of foods rich in cholesterol and saturated fats warrants dietary advice, for the expectation is good that he will respond.”
  • “The 2 components in dietary treatment of the Type II abnormality are limited intake of cholesterol and the substitution of polyunsaturated for saturated fats. Cholesterol and saturated (usually from animal) fats occur together in foods, and many therapists today are more concerned with their elimination […]”
  • “Substitution of skim-milk over whole-milk products, severe restriction or even elimination of egg yolks and reduction in meat intake for a daily intake of about 100 mg of cholesterol and 20 to 30 g of fat is one of the most effective dietary regimens.”
  • “Most Type II patients (provided they have normal glucose tolerance) can tolerate carbohydrate intakes of approximately 4 or 5 gm. Per kilogram of body weight per day without significant rise in their glyceride concentrations.”

That particular paper he cited dealt with only Type II of the five types of abnormal lipoprotein metabolism. Just FYI. He cites others though. Continuing with Taubes on that same paragraph:

By far the most common of the five lipoprotein disorders was the one designated Type IV, characterized by elevated VLDL triglycerides-“sometimes considered synonymous with ‘carbohydrate-induced hyperlipemia,'” they wrote-and it had to be treated with a low-carbohydrate diet.

Wrong on so many levels. Let’s take a look at the quote first. Taubes excises what follows that quote because the authors go on to say that while some might classify Type IV as “carbohydrate-induced,” it is really not true. Here’s the entire quote on page 273 of the same Fredrickson series, bolding mine:

The Type IV pattern (hereafter called simply “Type IV”) is a valuable indicator of metabolic imbalance; it does not describe a specific disease. It is sometimes considered synonymous with “carbohydrate-induced hyperlipemia.” This is probably too narrow a concept since most patients who have this pattern on a regular diet do not lose it entirely when their diet is changed so that 10 per cent of their calories come from carbohydrate, and an occasional patient does not have an abnormal increase in plasma glycerides when fed 80 per cent of his calories as carbohydrate.

That deals with the blatant quote-mining. What about the claim that the treatment had to be a low-carb diet? The authors also clearly state that carbohydrates should not be assumed to be the cause of the hyperlipemia, at least regarding Type IV, and that weight loss should be considered the primary treatment of such a disorder.

How does Taubes get away with this?

* * *

From page 168 in the hardback:

When they finally were tested in two clinical trials in the 1990s—the Lyon Diet Heart Trial and an Italian study known as GISSI-Prevenzione—both supported the contention that the diet prevented heart attacks, but neither provided evidence that it did so by either raising HDL or lowering LDL, which was how it was now alleged to work

The GISSI study does not measure diet.10 The diets remain the same throughout. The variable of interest in the study is one omega-3 gel capsule with the primary endpoints being death, non-fatal myocardial infarction, and stroke (i.e. not cholesterol). Conclusion: Dietary supplementation with n-3 PUFA led to a clinically important and statistically significant benefit. This study does not prove his claim.

Regarding the Lyon Diet Heart trial, Taubes’s inclusion of HDL and LDL makes his claim technically correct. However, the results of the Lyon Diet Heart trial are actually pretty devastating to Taubes’s overall thesis. What Taubes leaves out is that total cholesterol was very predictive of a second myocardial infarction. From the study: “[E]ach increase of 1 mmol/L of total cholesterol increased the risk of recurrence by 20% to 30%.”11 Not to mention the experimental diet contained – among other things – less saturated fat.

* * *

On pages 168-169:

Consider a porterhouse steak with a quarter-inch layer of fat. After broiling, this steak will reduce to almost equal parts fat and protein. Fifty-one percent of the fat is monounsaturated, of which 90 percent is oleic acid. Saturated fat constitutes 45 percent of the total fat, but a third of that is stearic acid, which will increase HDL cholesterol while having no effect on LDL. (Stearic acid is metabolized in the body to oleic acid, according to Grundy’s research.) The remaining 4 percent of the fat is polyunsaturated, which lowers LDL cholesterol but has no meaningful effect on HDL. In sum, perhaps as much as 70 percent of the fat content of a porterhouse steak will improve the relative levels of LDL and HDL cholesterol, compared with what they would be if carbohydrates such as bread, potatoes, or pasta were consumed. The remaining 30 percent will raise LDL cholesterol but will also raise HDL cholesterol and will have an insignificant effect, if any, on the ratio of total cholesterol to HDL. All of this suggests that eating a porterhouse steak in lieu of bread or potatoes would actually reduce heart-disease risk, although virtually no nutritional authority will say so publicly. The same is true for lard and bacon.

For this paragraph of claims Taubes cites two studies, one by Katan and one by Grundy.12,13 He also cites the USDA National Nutrient Database for the fatty acid profile of his hypothetical steak.

If you actually look at the National Nutrient Database for a porterhouse steak you will note that Taubes is correct when he breaks down the fatty acid composition. However, you’ll notice that he focuses on the stearic acid (18:0) which is only one-third of the SFAs, the other two-thirds that he neglects to mention is palmitic acid (16:0) which according to the Katan study he cites raises LDL cholesterol monumentally compared to stearic acid.
Nutrient data for 23002, Beef, short loin, porterhouse steak, trimmed to 0.12 fat, cooked, broiled

fatty acids and cholesterol

As for the claim that the “remaining 4 percent of the fat is polyunsaturated, which lowers LDL cholesterol but has no meaningful effect on HDL,” this is blatantly untrue, even by the studies Taubes himself cites.

fatty acids and cholesterol2

Again, does Taubes even bother to read the studies he cites?

“All of this suggests that eating a porterhouse steak in lieu of bread or potatoes would actually reduce heart-disease risk, although virtually no nutritional authority will say so publicly.”

I’m not sure he can make that claim. Based on his own references, carbs seem to decrease both HDL and LDL. That would suggest a more-or-less neutral effect on the HDL/LDL ratio and therefore a neutral effect on CVD.
fatty acids and cholesterol3

By the way, does Taubes now accept that cholesterol plays a role in heart disease? It seems that the reason red meat is beneficial for you, according to Taubes, is that is helps lower LDL and raise HDL. The same notion he was arguing against the entire chapter! Moreover, it seems that the source of the cholesterol-mitigating properties is the unsaturated fats that are found more abundantly in vegetable oils. Here’s Taubes again:

The observation that monounsaturated fats both lower LDL cholesterol and raise HDL also came with an ironic twist: the principal fat in red meat, eggs, and bacon is not saturated fat, but the very same monounsaturated fat as in olive oil.

So why not just go for the olive oil? Oh yeah, because vegetable fats cause cancer or some such nonsense. But not meat, of course; it’s perfect.

Refs

 

1. Ahrens, E. H., Jr et al. Dietary control of serum lipids in relation to atherosclerosis. JAMA 164, 1905–1911 (1957).

2. Kuo PT. Hyperglyceridemia in coronary artery disease and its management. JAMA 201, 87–94 (1967).

3. Goldstein, J. L., Hazzard, W. R., Schrott, H. G., Bierman, E. L. & Motulsky, A. G. Hyperlipidemia in Coronary Heart Disease I. Lipid Levels in 500 Survivors of Myocardial Infarction. J. Clin. Invest. 52, 1533–1543 (1973).

4. Carlson, L. & Böttiger, L. E. Ischaemic heart-disease in relation to fasting values of plasma triglycerides and cholesterol. Stockholm prospective study. The Lancet 299, 865–868 (1972).

5. Chapter XIII: Serum Triglyceride Changes. Circulation 37, I–224–I–226 (1968).

6. Kannel, W. B., Castelli, W. P., Gordon, T. & McNamara, P. M. Serum Cholesterol, Lipoproteins, and the Risk of Coronary Heart Disease: The Framingham Study. Ann. Intern. Med. 74, 1–12 (1971).

7. In fact, Taubes’s citation for Framingham here is actually a newspaper article that doesn’t even mention Framingham. I am assuming it is an innocent citation error.

8. Keys, A. Coronary heart disease in seven countries. I. The study program and objectives. Circulation 41, I1–8 (1970).

9. Fredrickson, D. S., Levy, R. I. & Lees, R. S. Fat Transport in Lipoproteins — An Integrated Approach to Mechanisms and Disorders. N. Engl. J. Med. 276, 34–44 (1967).

10. Dietary supplementation with n-3 polyunsaturated fatty acids and vitamin E after myocardial infarction: results of the GISSI-Prevenzione trial. The Lancet 354, 447–455 (1999).

11. De Lorgeril, M. et al. Mediterranean Diet, Traditional Risk Factors, and the Rate of Cardiovascular Complications After Myocardial Infarction: Final Report of the Lyon Diet Heart Study. Circulation 99, 779–785 (1999).

12. Katan, M. B., Zock, P. L. & Mensink, R. P. Dietary oils, serum lipoproteins, and coronary heart disease. Am. J. Clin. Nutr. 61, 1368S–1373S (1995).

13. Grundy, S. M. Influence of stearic acid on cholesterol metabolism relative to other long-chain fatty acids. Am. J. Clin. Nutr. 60, 986S–990S (1994).
 

Good Calories, Bad Calories: A Critical Review; Chapter 1 – The Eisenhower Paradox

cover

Introduction

This is something of an ongoing review, chapter by chapter, of Gary Taubes’s extraordinarily dense book Good Calories, Bad Calories, which I usually shorten to GCBC. You might even consider this more of a fact-checking than a review, but whatever. I’m not going to get into a semantic argument. I wrote my first review of this book back in 2012, but after writing it I felt very unsatisfied. GCBC is such a dense book filled with so many unsubstantiated claims that I felt the book demanded a more thorough review. Other bloggers, like James Krieger at Weightology, seem to feel the same way and have tried to provide such a review only to eventually give up once they realize the gravity of the task. I may also give up at some point. I actually have given up a number of times only to feel compelled to hit at least one more chapter.

If you would like to read other parts of this ongoing review go to the table of contents on my Book Reviews page. FYI: All page numbers in this review refer to the hardback version of the book.

Not the Introduction

Early in the chapter Taubes claims that most mainstream nutrition authorities were saying that the American diet changed during the 20th century, from a plant-based diet to a diet heavy in meat. On pages 10 and 11 he attempts to refute this notion by saying that the USDA statistics from which this notion is drawn is very flawed, citing a personal interview with David Call and a paper on food disappearance data.1 Specifically he says

  • “The USDA statistics, however, were based on guesses, not reliable evidence.”

  • “The resulting numbers for per-capita consumption are acknowledged to be, at best, rough estimates.”

  • “The reports remained sporadic and limited to specific food groups until 1940 […] Until then, the data were particularly sketchy…”

However, the very next paragraph he makes the argument that the US has always been a meat-eating country, and as evidence he cites data from the USDA! “By one USDA estimate, the typical American was eating 178 pounds of meat annually in the 1830s, forty to sixty pounds more than was reportedly being eaten a century later.” Either the food stats are reliable before 1940 or the are not. Pick a side and be consistent.

He’s really all over the map in this section because he then claims that in fact we did eat less meat in the early 20th century due to a few reasons: the cattle industry could not keep up with population growth, meat rationing during WW1, and Upton Sinclair’s The Jungle. He then makes the argument that Americans started eating more fruits and vegetables and decreased consumption of animal products. Following this change, incidents of heart disease skyrocketed to become an epidemic – an epidemic that earlier in the chapter he claims was completely bogus.

* * *

On pages 14 and 15 Taubes talks a bit about cholesterol and says

Despite myriad attempts, researchers were unable to establish that patients with atherosclerosis had significantly more cholesterol in their bloodstream than those who didn’t. “Some works claim a significant elevation in blood cholesterol level for a majority of patients with atherosclerosis,” the medical physicist John Gofman wrote in Science in 1950, “whereas others debate this finding vigorously. Certainly a tremendous number of people who suffer from the consequences of atherosclerosis show blood cholesterols in the accepted normal range.”

It’s interesting to note that immediately after that sentence in the cited text Gofman also wrote2

There does exist a group of disease states (including diabetes mellitus, nephrotic nephritis, severe hypothyroidism, and essential familial hypercholesteremia) in which the blood cholesterol level may be appreciably elevated. Such patients do show, in general, earlier and more severe atherosclerosis than the population at large.

In fact, most of the text makes the case that there are particular cholesterol particles to blame for atherogenesis, specifically those with a density of 10-20 Svedberg units that are currently known as LDL. However, since this paper was published in 1950 they are referred to as the Sf 10-20 class of cholesterol molecules. Gofman also noted – prior to even anything that Keys published on the subject – that dietary lipids affect these Sf 10-20 molecules, stating:

Our preliminary study of a group of 20 patients whose diet we have restricted in cholesterol and fats has demonstrated that the concentration of the Sf 10-20 class of molecules is definitely reduced or even brought down to a level below resolution ultracentrifugally in 17 of the cases studied within two weeks to one month.

I can’t understand why Taubes didn’t mention that, can you?

* * *

Taubes knocks me for a loop on page 15 when he states:

The condition of having very high cholesterol—say, above 300 mg/dl—is known as hypercholesterolemia. If the cholesterol hypothesis is right, then most hypercholesterolemics should get atherosclerosis and die of heart attacks. But that doesn’t seem to be the case.

Actually that seems to be exactly the case… even by the study Taubes cites.

Coronary Artery Disease in 116 Kindred with Familial Type II Hyperlipoproteinemia

click to embiggen

click to embiggen

That study even seems to be in agreement with the other studies on familial hypercholesterolemia at the time3:

Our results are qualitatively similar to analyses on a smaller scale which have established an enhanced risk of premature CAD in affected members of families with familial hypercholesterolemia.

But since certain thyroid and kidney disorders might also cause hypercholesterolemia I suppose Taubes can just ignore all that evidence linking cholesterol to heart disease.

* * *

Pg. 15

Autopsy examinations had also failed to demonstrate that people with high cholesterol had arteries that were any more clogged than those with low cholesterol. In 1936, Warren Sperry, co-inventor of the measurement technique for cholesterol, and Kurt Landé, a pathologist with the New York City Medical Examiner, noted that the severity of atherosclerosis could be accurately evaluated only after death, and so they autopsied more than a hundred very recently deceased New Yorkers, all of whom had died violently, measuring the cholesterol in their blood. There was no reason to believe, Sperry and Landé noted, that the cholesterol levels in these individuals would have been affected by their cause of death (as might have been the case had they died of a chronic illness). And their conclusion was unambiguous: “The incidence and severity of atherosclerosis are not directly affected by the level of cholesterol in the blood serum per se.”

I was unable to find the cited Landé and Sperry paper. It is so old and obscure that not only was I unable to find it, the databases I used (PubMed, WorldCat, Academic Search Complete) could not find a record of it even existing. But let’s do something we probably should not do and take Taubes at his word here. It is still interesting to note that this is an example of an observational study, specifically a cross-sectional study. Later in the book Taubes will make the case that observational studies are worthless. In fact, you will see throughout the book that Taubes will cite observational studies, usually without caveat, if it fits his meat-is-good narrative. However, if he doesn’t like the conclusion of a study (observational or otherwise) you will find that he impugns the methodology, the authors, or even the entire field of science of which it is a part. Get your popcorn ready.

* * *

Like the above point, this is not a real significant issue, but it shows that Taubes is not above quote mining to try and paint someone in a negative light. On page 16:

Henry Blackburn, his longtime collaborator at Minnesota, described him as “frank to the point of bluntness, and critical to the point of sharpness.” David Kritchevsky, who studied cholesterol metabolism at the Wistar Institute in Philadelphia and was a competitor, described Keys as “pretty ruthless” and not a likely winner of any “Mr. Congeniality” awards.

I imagine the point of these quotes is to paint Keys as kind of an asshole, just in case any reader might find themselves sympathizing with Keys when Taubes takes massive, diarrhea-like shits all over Keys’s research and Keys personally. I cannot verify the Kritchevsky quote above because it was from a personal interview, but adding a bit of context to the Blackburn quote can change the tone entirely4:

Ancel Keys has a quick and brilliant mind, a prodigious energy, and great perseverance. He can also be frank to the point of bluntness, and critical to the point of sharpness. But by the boldness of his concepts, the vigor of his pursuits, and the rigor of his methods, as well as by his personal example, he led several generations of investigators in making powerful contributions to the public health.

The entire article is actually quite praiseworthy.

* * *

Pg. 15:

This was a common finding by heart surgeons, too, and explains in part why heart surgeons and cardiologists were comparatively skeptical of the cholesterol hypothesis. In 1964, for instance, the famous Houston heart surgeon Michael DeBakey reported similarly negative findings from the records on seventeen hundred of his own patients. And even if high cholesterol was associated with an increased incidence of heart disease, this begged the question of why so many people, as Gofman had noted in Science, suffer coronary heart disease despite having low cholesterol, and why a tremendous number of people with high cholesterol never get heart disease or die of it.

I’m not sure why Taubes names DeBakey as the primary source here, since he was actually the fourth author in the study that was cited, but no matter… It’s interesting to find that if you check the 1964 paper that is cited, it’s a type of observational study called a case series that examines 1,700 surgical patients treated for some sort of atherosclerosis.5 Turns out 1,416 out of the 1,700 (or 83%) have what the Mayo Clinic would describe as “high” cholesterol levels (over 200 mg/dL).

Does Taubes even read the studies he cites? Or does he read them and deliberately misrepresent them?

A second paper he cites in support of that paragraph is not even a study, but a statement by the president of the American Heart Association6 (wait… they’re supposed to be the bad guys, right?). He says many things in that statement, but what is most relevant to this paragraph is he says that

In a nation of over a quarter of a billion people we are a remarkably heterogeneous lot, and in truth there are no two of us alike. Those with low cholesterols as a group seem to have less coronary disease than those with high cholesterols, but this is too often extrapolated to apply directly to one individual.

He goes on to expound that, sure, cholesterol levels are important, but sometimes people get heart disease and don’t have high cholesterol levels so we should individualize our advice. I don’t think it really helps or hurts Taubes’s argument, but evidently he cited it anyway. Probably to pad his references.

* * *

If Taubes’s irrational contempt for Keys was not obvious before, it should be crystal clear after this passage on page 16:

When Keys launched his crusade against heart disease in the late 1940s, most physicians who believed that heart disease was caused by diet implicated dietary cholesterol as the culprit. We ate too much cholesterol-laden food—meat and eggs, mostly—and that, it was said, elevated our blood cholesterol. Keys was the first to discredit this belief publicly, which had required, in any case, ignoring a certain amount of the evidence.

Before Keys came along all of the “evidence” that dietary cholesterol substantially affects serum cholesterol was from animal studies. Studies that, just two pages earlier, Taubes argues have no bearing on human physiology. So Keys decides to conduct some cholesterol research on actual humans, and concludes that dietary cholesterol actually doesn’t have a substantial effect on serum cholesterol.7 If this were anyone else other than Keys Taubes would likely praise them for not following the conventional wisdom of the day and conducting proper scientific research, but instead Keys is accused of “ignoring” evidence. I think that’s fair.

In the same paragraph as above Taubes discusses a cholesterol study:

In 1937, two Columbia University biochemists, David Rittenberg and Rudolph Schoenheimer, demonstrated that the cholesterol we eat has very little effect on the amount of cholesterol in our blood.

Although the statement “the cholesterol we eat has very little effect on the amount of cholesterol in our blood” is true for most people, as we have just discovered, the Rittenberg/Schoenheimer study that Taubes mentions has almost nothing to do with that statement.8 Firstly, the study was conducted on mice, and extrapolating results on people from cholesterol studies on animals are certainly dubious as Taubes himself admits. Moreover, the study itself involves feeding mice water labeled with deuterium then measuring deuterium in their cholesterol and fatty acids in the mice’s tissues to see how much deuterium had been incorporated into those molecules. As far as I can tell it has nothing to do with feeding them cholesterol and seeing if that impacts their blood cholesterol levels. But correct me if I am wrong.

Pg. 16 continued:

As a result, Keys insisted that dietary cholesterol had little relevance to heart disease. In this case, most researchers agreed.

Most researchers agreed… 16 years later.9

* * *

On page 17 Taubes writes:

By 1952, Keys was arguing that Americans should reduce their fat consumption by a third, though simultaneously acknowledging that his hypothesis was based more on speculation than on data: “Direct evidence on the effect of the diet on human arteriosclerosis is very little,” he wrote, “and likely to remain so for some time.”

This is another minor point, but it should be pointed out that THAT IS WHAT A HYPOTHESIS IS. It’s a guess based on little or no evidence, and all scientists have them. Just for context, here’s the quote from Keys that Taubes plucked with a bit more… umm… context10:

[W]e may remark that direct evidence on the effect of the diet on human atherosclerosis is very little and is likely to remain unsatisfactory for a long time. But such evidence as there is, plus valid inferences from indirect evidence, suggests that a substantial measure of control of the development of atherosclerosis in man may be achieved by control of the intake of calories and of all kinds of fats, with no special attention to the cholesterol intake. This means: (1) avoidance of obesity, with restriction of the body weight to about that considered standard for height at age 25; (2) avoidance of periodic gorging and even temporary large calorie excesses; (3) restriction of all fats to the point where the total extractable fats in the diet are not over about 25 to 30 per cent of the total calories; (4) disregard of cholesterol intake except, possibly, for a restriction to an intake less than 1 Gm. per week.

Taubes gets the quotation a smidge wrong, but it still keeps the spirit of the original. The bigger picture here is that Keys is recommending (in an academic journal, by the way) to avoid becoming obese, avoid gorging on food, a diet that’s about 30% fat, and to not worry too much about cholesterol intake. Pretty uncontroversial stuff, if you ask me. Yet Taubes portrays Keys here and elsewhere as some kind of radical crusader, religious zealot, idiot, and kind of an asshole.

* * *

On page 18 Taubes discusses a 1957 paper by Jacob Yerushalmy and Herman Hilleboe, which is something of a response to Ancel Keys’s 1953 paper Atherosclerosis: A Newer Problem in Public Health.11 If you’re not familiar with the Keys paper I will give you a brief synopsis. Keys published some data that suggested a remarkable relationship between fat in the diet and heart disease. Included in the paper was a striking (if oversimplified) figure looking at several countries and their population’s typical fat intake juxtaposed with deaths from heart disease.

YH4

Taubes says:

Many researchers wouldn’t buy it. Jacob Yerushalmy, who ran the biostatistics department at the University of California, Berkeley, and Herman Hilleboe, the New York State commissioner of health, co-authored a critique of Keys’s hypothesis, noting that Keys had chosen only six countries for his comparison though data were available for twenty-two countries. When all twenty-two were included in the analysis, the apparent link between fat and heart disease vanished. Keys had noted associations between heart-disease death rates and fat intake, Yerushalmy and Hilleboe pointed out, but they were just that. Associations do not imply cause and effect or represent (as Stephen Jay Gould later put it) any “magic method for the unambiguous identification of cause.”

I have actually written about this in a previous blog post, but I will revisit this again. Aside from the fact that Keys never claimed a cause-and-effect relationship (much less an unambiguous one) and always identified it as an association, Taubes completely misrepresents the results of the study. It’s true that after Yerushalmy and Hilleboe added more data into the graph the relationship becomes a bit more muddied, but it certainly does not vanish as Taubes claims. There is still a noticeable relationship.12 See for yourself.

YH1

What’s even more interesting is that Y&H actually conclude that consumption of animal fat and/or animal protein is much more strongly associated with heart disease than total fat. Moreover, vegetable fat and/or vegetable protein is actually negatively correlated with heart disease. The resolution is not very sharp, but here are the results. I’ll leave it to you to wonder why Taubes ignores this highly pertinent information.

YH3

YH-2

click to embiggen

See Taubes response #1

* * *

On pages 19-20 Taubes claims that Keys “insisted” that fat elevated cholesterol. I am not sure what Keys was doing that made him so insisting, other than writing a few academic articles concluding that there was an association between dietary fat and serum cholesterol (which there was), while also making sure to point out that there are many details about this association that have yet to be discovered (which there also were). Taubes then goes on to mention some studies that examined those details:

In 1952, however, Laurance Kinsell, director of the Institute for Metabolic Research at the Highland–Alameda County Hospital in Oakland, California, demonstrated that vegetable oil will decrease the amount of cholesterol circulating in our blood, and animal fats will raise it. That same year, J. J. Groen of the Netherlands reported that cholesterol levels were independent of the total amount of fat consumed: cholesterol levels in his experimental subjects were lowest on a vegetarian diet with a high fat content, he noted, and highest on an animal-fat diet that had less total fat. Keys eventually accepted that animal fats tend to raise cholesterol and vegetable fats to lower it, only after he managed to replicate Groen’s finding with his schizophrenic patients in Minnesota.

In other words, Keys did what any good scientist should do: he followed the evidence. Yet the syntax of the last sentence would have you imagine that Keys was some sort of stubborn asshole that refused to accept the truth until the evidence overwhelmed him.

* * *

This may be another nitpicky issue, but the following quote is misleading. Page 20:

This kind of nutritional wisdom is now taught in high school, along with the erroneous idea that all animal fats are “bad” saturated fats, and all “good” unsaturated fats are found in vegetables and maybe fish. As Ahrens suggested in 1957, this accepted wisdom was probably the greatest “handicap to clear thinking” in the understanding of the relationship between diet and heart disease.

First of all, I was never taught that kind of “nutritional wisdom” in high school. Come to think of it I was never taught any nutritional wisdom in high school, but that’s neither here nor there. My issue with this is that in the text that Taubes cites as the source of that quote, Ahrens does not say that the animal fat = bad / vegetable fat = good binarism is the greatest handicap to clear thinking. What he does say is that the good-bad dyad was a greater handicap than the confusion about why experimental diets were designed to be eucaloric.13

* * *

Tabues uses a 1957 review article titled “Atherosclerosis and the Fat Content of the Diet” as a source for three claims in this chapter. One is simply a block quote on page 8. The other two claims are very tenuous, especially the following found on page 20:

In 1957, the American Heart Association opposed Ancel Keys on the diet-heart issue.

The article does mention Keys a few times, as well as a number of other researchers involved with dietary research involving atherosclerosis, but it is very neutral on Keys. In fact, you might even say the author mildly endorses Keys at a couple of points: “Mayer et al. found that high-fat animal or vegetable diets increased and low-fat diets decreased serum cholesterol of normal subjects, confirming earlier data of Keys.” And “Keys, in particular, has placed emphasis on the proportion of total dietary calories contributed by the common food fats […] Certainly there is an abundance of data, both clinical and experimental, that tends to relate excess fat intake to atherosclerosis.”14

After reading the article I certainly didn’t get the idea that the AHA opposed Keys. Even if they did they never explicitly stated this.

* * *

On page 21 Taubes pulls some numbers from thin air:

As Time reported, Keys believed that the ideal heart-healthy diet would increase the percentage of carbohydrates from less than 50 percent of calories to almost 70 percent, and reduce fat consumption from 40 percent to 15 percent.

The Time article actually does report that Keys suggested American reduce their fat intake from 40 to 15 percent. However, there is no mention in the entire article about Keys recommending an increase in carbohydrates.15

Go to Good Calories, Bad Calories: A Critical Review; Chapter 2 – The Inadequacy of Lesser Evidence

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Refs

1. Call, D. L. & Sánchez, A. M. Trends in fat disappearance in the United States, 1909-65. J. Nutr. 93, Suppl:1–28 (1967).

2. Gofman, J. W. et al. The Role of Lipids and Lipoproteins in Atherosclerosis. Science 111, 166–186 (1950).

3. Stone, N. J., Levy, R. I., Fredrickson, D. S. & Verter, J. Coronary artery disease in 116 kindred with familial type II hyperlipoproteinemia. Circulation 49, 476–488 (1974).

4. Blackburn, H. Ancel Keys. at http://www.mbbnet.umn.edu/firsts/blackburn_h.html

5. Garrett H, Horning EC, Creech BG & De Bakey M. Serum cholesterol values in patients treated surgically for atherosclerosis. JAMA 189, 655–659 (1964).

6. James, T. N. Presidential address. AHA 53rd scientific sessions, Miami Beach, Florida, November 1980. Sure cures, quick fixes and easy answers. A cautionary tale about coronary disease. Circulation 63, 1199A–1202A (1981).

7. Keys, A., Anderson, J. T., Mickelsen, O., Adelson, S. F. & Fidanza, F. Diet and Serum Cholesterol in Man: Lack of Effect of Dietary Cholesterol. J. Nutr. 59, 39–56 (1956).

8. Rittenberg, D. & Schoenheimer, R. Deuterium as an indicator in the study of intermediary metabolism XI. Further studies on the biological uptake of deuterium into organic substances, with special reference to fat and cholesterol formation. J. Biol. Chem. 121, 235–253 (1937).

9. Quintão, E., Grundy, S. M. & Ahrens, E. H. Effects of dietary cholesterol on the regulation of total body cholesterol in man. J. Lipid Res. 12, 233–247 (1971).

10. Keys, A. Human Atherosclerosis and the Diet. Circulation 5, 115–118 (1952).

11. Keys, A. Atherosclerosis: a problem in newer public health. J. Mt. Sinai Hosp. N. Y. 20, 118–139 (1953).

12. Yerushalmy, J. & Hilleboe, H. E. Fat in the diet and mortality from heart disease; a methodologic note. N. Y. State J. Med. 57, 2343–2354 (1957).

13. Ahrens, E. H., Jr. Seminar on atherosclerosis: nutritional factors and serum lipid levels. Am. J. Med. 23, 928–952 (1957).

14. Page, I. H., Stare, F. J., Corcoran, A. C., Pollack, H. & Wilkinson, C. F., Jr. Atherosclerosis and the fat content of the diet. Circulation 16, 163–178 (1957).

15. The Fat of the Land. Time 77, 48 (1961).

Good Calories, Bad Calories: A Critical Review; Chapter 3 – Creation of Consensus

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Introduction

This is something of an ongoing review, chapter by chapter, of Gary Taubes’s extraordinarily dense book Good Calories, Bad Calories, which I usually shorten to GCBC. You might even consider this more of a fact-checking than a review, but whatever. I’m not going to get into a semantic argument. I wrote my first review of this book back in 2012, but after writing it I felt very unsatisfied. GCBC is such a dense book filled with so many unsubstantiated claims that I felt the book demanded a more thorough review. Other bloggers, like James Krieger at Weightology, seem to feel the same way and have tried to provide such a review only to eventually give up once they realize the gravity of the task. I may also give up at some point. I actually have given up a number of times only to feel compelled to hit at least one more chapter.

If you would like to read other parts of this ongoing review go to the table of contents on my Book Reviews page. FYI: All page numbers in this review refer to the hardback version of the book.

Not the Introduction

Near the beginning of chapter three Taubes makes some serious unfounded claims. From page 44:

This alliance between the AHA and the makers of vegetable oils and margarines dissolved in the early 1970s, with reports suggesting that polyunsaturated fats can cause cancer in laboratory animals. This was problematic to Keys’s hypothesis […]

Polyunsaturated fats cause cancer?!?!?! That’s a bold claim for which Taubes cites two supporting texts. One is a New York Times article from 1973 titled “Heart Association Strengthens its Advice: Cut Down on Fats,” and it barely has anything to do with Taubes’s claim.1 It mostly deals with atherosclerosis (not cancer), and hardly discusses polyunsaturated fats. The closest thing you will find that even comes close to supporting the claim that “polyunsaturated fats can cause cancer in laboratory animals” is near the end of the article. There is a section titled Challenges and Answers that states the following:

Despite this evidence, doubts and doubters remain. Some of the challenges to the heart disease-fatty diet thesis, and the answers from the heart association, follow: […] Polyunsaturates are dangerous. Dr. Mueller says that there is no evidence that consumption of polyunsaturates is harmful at the recommended levels or even considerably above these levels. While such consumption is known to increase the body’s need for vitamin E, most vegetable oils contain enough vitamin E to satisfy the need.

Hmmm… Is that strong evidence for his claim? Nope. What about the other citation? It not a study involving laboratory animals, but rather a trial of elderly veterans.2 Turns out the data from that trial show a few more people dying from cancer on a diet high in polyunsaturated fat. But the results from the study were something of an outlier. The authors even mention this:

The experience of other investigators using similar diets has not been the same. […] Many of the cancer deaths in the experimental group were among those who did not adhere closely to the diet. This reduces the possibility that the feeding of polyunsaturated oils was responsible for the excess carcinoma mortality observed in the experimental group. […] In both groups, the numbers of cancer deaths among the various adherence strata are compatible with random distribution (table v). A high incidence among high adherers would be expected if some constituent of the experimental diet were contributing to cancer fatality.

Again you must ask yourself “Is this evidence strong enough to justify the claim that polyunsaturated fats cause cancer in laboratory animals?” It’s up to you to decide. I might even ask myself a few more questions like “Is this an innocent citation error? Certainly a book of this depth and magnitude is bound to have a few simple human errors. If it is an honest mistake, why do all the mistakes happen to be in favor of a low-carb, high-fat diet?”

Taubes also uses this study later in the chapter so we’ll revisit this soon. See Taubes response #2 and #3.

 * * *

In chapter three Taubes devotes much ink to slandering discussing the 1977 publication of Dietary Goals for the United States by a committee led by George McGovern. Now I have no problem criticizing the government. In fact, I think that one of the great things about living in the US is the right to just trash the hell out of the government and politicians either in private or in the public eye. I encourage everyone to exercise that right if they see fit; however, criticisms have a little more bite to them when they are actually legitimate. Much of the cited evidence against the Dietary Goals comes from what were ostensibly personal interviews with a few people involved with its drafting. Of course, no one is privy to this information so we can only go on what is publicly available.

On page 46-47 Taubes claims:

Dietary Goals was couched as a plan for the nation, but these goals obviously pertained to individual diets as well. Goal number one was to raise the consumption of carbohydrates until they constituted 55–60 percent of the calories consumed. Goal number two was to decrease fat consumption from approximately 40 percent, then the national average, to 30 percent of all calories, of which no more than a third should come from saturated fats. The report acknowledged that no evidence existed to suggest that reducing the total fat content of the diet would lower blood-cholesterol levels, but it justified its recommendation on the basis that, the lower the percentage of dense fat calories in the diet, the less likely people would be to gain weight, and because other health associations—most notably the American Heart Association—were recommending 30 percent fat in diets. To achieve this low-fat goal, according to the Dietary Goals, Americans would have to eat considerably less meat and dairy products.

When Taubes says “The report acknowledged that no evidence existed to suggest that reducing the total fat content of the diet would lower blood-cholesterol levels…” he is using a straw man that I’m fairly certain is not even discussed in Dietary Goals. By this point total fat was not the issue, but type of fat was and Dietary Goals discusses the evidence that a diet low in saturated fat and high in unsaturated fat will decrease blood-cholesterol levels. Also, I saw no recommendations for eating “considerably less meat and dairy products,” but please correct me if I am wrong.

Taubes’s arguments against Dietary Goals are not even internally consistent at times. For instance on page 45 Taubes writes “McGovern’s staff were virtually unaware of the existence of any scientific controversy” and “They believed that the relevant nutritional and social issues were simple and obvious.” Yet on page 47 Taubes writes “Though the Dietary Goals admitted the existence of a scientific controversy, it also insisted that Americans had nothing to lose by following the advice.” So did the authors know about a controversy or not? I suppose you could imagine a scenario where the authors knew nothing of a controversy yet wrote about one in an official government document anyway, but it seems specious to me.

Let’s go further into Taubes’s Dietary Goals bloodbath shall we? On page 46…

Having held one set of hearings before publishing the Dietary Goals, McGovern responded to the ensuing uproar with eight follow-up hearings. Among those testifying was Robert Levy, director of the National Heart, Lung, and Blood Institute, who said that no one knew whether lowering cholesterol would prevent heart attacks, which was why the NHLBI was spending several hundred million dollars to study the question.

Would Gary Taubes, a New York Times columnist and alumnus of the Ivy Leagues, possibly take someone out of context to misrepresent their position in order to fit his own low-carb narrative? Surely not. But just to be sure let us add a bit more context to Dr. Levy’s statements.3

We have no doubt from the vast amount of epidemiological data available that elevated cholesterol is associated with an increased risk of heart attack, especially some specific types of high cholesterol. We have no doubt that [blood] cholesterol can be lowered by diet and/or medication in most patients. Where the doubt exists is the question of whether lowering [blood] cholesterol will result in a reduced incidence of heart attack; that is still presumptive. It is unproven, but there is a tremendous amount of circumstantial evidence. Not only is there circumstantial epidemiologic data, but there is very exciting animal data. Here is one of many studies that have been done over the last decade with nonhuman primates. It shows that not only can we prevent atherosclerosis from progressing by making dietary changes, but that regression actually occurs. Atherosclerosis will lessen if we lower [blood] cholesterol levels in animals through diet. The problem is we can’t do these kinds of studies in man; it is not ethical. There is no doubt that [blood] cholesterol can be lowered by diet in free-living populations. It can be lowered by 10 to 15 percent.

You have to ask yourself whether Taubes’s characterization of Levy’s testimony is really an accurate representation of Levy’s actual testimony. As a reader are you at all angry that a science journalist like Taubes misrepresents people over and over again? I am genuinely curious. Let me know in the comments section.

 * * *

Taubes makes stuff up again on page 49:

The ASCN committee concluded that saturated-fat consumption was probably related to the formation of atherosclerotic plaques, but the evidence that disease could be prevented by dietary modification was still unconvincing.*

*It also affirmed the suspicion that polyunsaturated fats might be dangerous, and so further diminished the role of margarines and corn oils in dietary recommendations.

As evidence Taubes cites a paper titled The Evidence Relating Six Dietary Factors to the Nation’s Health by Dr. Ahrens.4 The paper gives a score of 0-100 to associations between a given dietary issue and atherosclerosis, where 0 is the weakest evidence for the association and 100 is the most rock-solid evidence. The final score is an aggregation of scores by several experts in the field based on epidemiological evidence, animal studies, human interventions, autopsies, biological plausibility, etc. Cholesterol alone received a score of 62. Saturated fat alone received a 58. Cholesterol and fat together received a 73. For comparison the association between alcohol and liver disease received an 88, and the association between carbohydrate and atherosclerosis got an 11. Carbohydrate and diabetes got a 13.

I don’t want to tell you how you should interpret that data, but it seems pretty clear to me that the evidence that cholesterol and fat play a role in atherosclerosis is quite strong: well above the halfway point and approaching the level of alcohol and liver disease. Taubes, however, tells his readers that the committee found the evidence “unconvincing” for reasons that should be pretty clear by now.

He also tells his readers that the ASCN committee affirmed that polyunsaturated fats might be dangerous, which apparently diminishes the role of margarine and corn oil. However, the committee claims nothing of the sort; there is no implied subtext either. In fact, there is literally no mention of polyunsaturated fats, corn oil, or margarine.

He does cite a separate paper that, as far as I can tell, has nothing to do with the ASCN committee paper other than being published by the same journal.5 There is still no mention of corn oil or margarine or any kind of affirmation that polyunsaturated fats might be dangerous. In fact, the text claims that polyunsaturated fats are generally beneficial, but that the long term effects of specific concerns such as lipid peroxidation of polyunsaturates have yet to be studied.

* * *

On page 54 Taubes strongly implies (like he has done before) that polyunsaturated fats and low levels of cholesterol leads to cancer and death:

The other disconcerting aspect of these studies is that they suggested (with the notable exception of three Chicago studies reported by Jeremiah Stamler and colleagues) low cholesterol levels were associated with a higher risk of cancer. This link had originally been seen in Seymour Dayton’s VA Hospital trial in Los Angeles, and Dayton and others had suggested that polyunsaturated fats used to lower cholesterol might be the culprits.

Dayton actually suggests the opposite in that very study. Pearce and Dayton actually do conduct a trial with elderly veterans where two groups are fed more-or-less the same diet, except one diet has more polyunsaturated fats in it. The results do indicate that in fact the group eating the diet with more polyunsaturates does have a few more cancer deaths in the group. But, as Taubes would say, there were caveats. I’ll let the authors explain:

The experience of other investigators using similar diets has not been the same. […] Many of the cancer deaths in the experimental group were among those who did not adhere closely to the diet. This reduces the possibility that the feeding of polyunsaturated oils was responsible for the excess carcinoma mortality observed in the experimental group. […] In both groups, the numbers of cancer deaths among the various adherence strata are compatible with random distribution (table v). A high incidence among high adherers would be expected if some constituent of the experimental diet were contributing to cancer fatality.

Indeed, other investigators’ experiences was not the same. A survey of five similar dietary trials published that same year suggested there was no link between low serum cholesterol and cancer.6 There are a handful of studies you can find that will support the link between cancer and low cholesterol, though. You can find them. But perhaps those results are due to the cholesterol-lowering effects of cancer, not the other way around.7

In fact, the authors of the MRFIT study (of which Taubes displays the results in the next chapter) explicitly mention this.8 In case you’re interested:

The increased total mortality at the lowest cholesterol levels has been noted before. It is primarily due to an increased risk of cancer death in those with the lowest cholesterol concentrations and is probably explained by a cholesterol-lowering effect of cancer. The most recent evidence for this explanation is an analysis of the MRFIT screening cohort which showed that the association between low serum cholesterol and cancer incidence does not persist beyond 5 years of follow-up, whereas that between high serum cholesterol and CHD incidence remains after 5 years.

In any case, regardless of whether or not it was evident to Taubes at the time GCBC was published, the results are in: a recent meta-analysis of 27 large-scale human trials confirmed no association between low cholesterol levels and cancer.9 Of course Taubes would probably demand a large, randomized clinical trial where healthy people are randomly assigned to get cancer and then have their cholesterol levels measured before accepting it. Hell, even then he would probably find a way to dismiss it. Dismissing good evidence that contradicts him is one of Taubes’s greatest skills.

* * *

On pages 53-54 Taubes discusses several studies that have found negative correlations between carbohydrate intake and heart disease.10,11 In other words, studies that have found that carbohydrates may be slightly protective against heart disease. Uh, oh! It’s time for Taubes to do some serious spinning. But remember what I said above? This is his specialty. He has a PhD in spinning science. You might even call him a Spin Doctor! Get it? Okay, here’s what he says:

When one is reading this report, it’s hard to avoid the suspicion that once the government began advocating fat reduction in the American diet it changed the way many investigators in this science perceived their obligations. Those who believed that dietary fat caused heart disease had always preferentially interpreted their data in the light of that hypothesis. Now they no longer felt obliged to test any hypothesis, let alone Keys’s. Rather, they seemed to consider their obligation to be that of “reconciling [their] study findings with current programs of prevention,” which meant the now official government recommendations. Moreover, these studies were expensive, and one way to justify the expense was to generate evidence that supported the official advice to avoid fat. If the evidence didn’t support the recommendations, then the task was to interpret it so that it did.

Now scientists can’t even be trusted!! Why? They’re greedy whores, of course; willing to do and say anything to keep those sweet, sugary NSF grants rolling in. Researchers have to maintain their lavish lifestyle, and if that means lying to the public and a few people get diabetes and die because of it, well, so be it. Health scientists didn’t get into the field of research because of a love of science or truth or the public good – they did it for the cold, hard cash.

Not only is that sentiment one of the most cynical things I have ever read, it is completely absurd and without merit. (I wonder if there are issues of psychological projection here; like when a cheating spouse unreasonably accuses their partner of cheating.) And lest you think Taubes took that quote from some secret literature of the Scientist Guild that shares tips and tricks on how to bilk the government out of research funding and promote chronic diseases for shits and giggles, here is a little more context:

Although the findings reported here – particularly those related to starch intake – may eventually be found to have practical implications, it would be premature to propose dietary alterations before the findings are examined more carefully. We consider the inverse relation of CHD incidence to the total daily caloric intake as a prescription for greater physical activity rather than for greater caloric intake.

[…]

The apparently protective effect of starch consumption against CHD seems to imply that the proportion of calories coming from starch should be increased. In isocaloric diets, increased intake of starch is a logical way to balance decreased intake of fat. Thus, from a practical point of view there is no difficulty in reconciling our study findings with current programs for prevention of CHD.

Doesn’t really sound so evil, does it? And by the way, there was never any official government “advice to avoid fat.” Never. The Dietary Goals for the United States that Taubes keeps hammering away at recommended a diet consisting of one-third fat. ONE-THIRD. This is not in any way a low-fat diet or advice to avoid fat. What it is is Taubes’s favorite straw man. For the record Dietary Goals recommended Americans cut their sugar intake by nearly 50%, yet no praise was given for that decision. I wonder why.

* * *

On page 57 Taubes discusses a study, the results of which he doesn’t like because they show that lowering cholesterol reduced nonfatal heart attacks, fatal heart attacks, and overall death. Watch the master of spin work his magic:

Nonetheless, these results were taken as sufficient by Rifkind, Steinberg, and their colleagues so they could state unconditionally that Keys had been right and that lowering cholesterol would save lives. Rifkind and his collaborators also concluded that the cholesterol-lowering benefits of a drug applied to diet as well. Although the trial included only middle-aged men with cholesterol levels higher than those of 95 percent of the population, Rifkind and his colleagues concluded that those benefits “could and should be extended to other age groups and women and…other more modest elevations of cholesterol levels.”

Isn’t he good? By the way, the cited source for that Rifkind quote is a National Heart, Lung, and Blood Institute consensus conference, and those words do not appear in it.12

Go to Good Calories, Bad Calories: A Critical Review; Chapter 4 – The Greater Good

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Refs

1. Brody, J. Heart Association Strengthens Its Advice: Cut Down on Fats. N. Y. Times 54 (1973).

2. Pearce, M. L. & Dayton, S. Incidence of cancer in men on a diet high in polyunsaturated fat. Lancet 1, 464–467 (1971).

3. United States. Dietary goals for the United States. (U.S. Govt. Print. Off., 1977). at <http://catalog.hathitrust.org/Record/011389409&gt;

4. Ahrens, E. H. The evidence relating six dietary factors to the Nation’s health. Introduction. Am. J. Clin. Nutr. 32, 2627–2631 (1979).

5. Glueck, C. J. Appraisal of dietary fat as a causative factor in atherogenesis. Am. J. Clin. Nutr. 32, 2637–2643 (1979).

6. Ederer, F., Leren, P., Turpeinen, O. & Frantz, I. Cancer among men on cholesterol-lowering diets: Experience from five clinical trials. The Lancet 298, 203–206 (1971).

7. Rose, G. & Shipley, M. J. Plasma lipids and mortality: a source of error. The Lancet 315, 523–526 (1980).

8. Martin, M. J., Browner, W. S., Hulley, S. B., Kuller, L. H. & Wentworth, D. Serum cholesterol, blood pressure, and mortality: implications from a cohort of 361,662 men. The Lancet 328, 933–936 (1986).

9. Cholesterol Treatment Trialists’ (CTT) Collaboration. Lack of Effect of Lowering LDL Cholesterol on Cancer: Meta-Analysis of Individual Data from 175,000 People in 27 Randomised Trials of Statin Therapy. PLoS ONE 7, e29849 (2012).

10. Yano, K., Rhoads, G. G., Kagan, A. & Tillotson, J. Dietary intake and the risk of coronary heart disease in Japanese men living in Hawaii. Am. J. Clin. Nutr. 31, 1270–1279 (1978).

11. Gordon, T. et al. Diet and its relation to coronary heart disease and death in three populations. Circulation 63, 500–515 (1981).

12. Consensus Conference. Lowering blood cholesterol to prevent heart disease. JAMA 253, 2080–2086 (1985).

Good Calories, Bad Calories: A Critical Review; Chapter 4 – The Greater Good

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Introduction

This is something of an ongoing review, chapter by chapter, of Gary Taubes’s extraordinarily dense book Good Calories, Bad Calories, which I usually shorten to GCBC. You might even consider this more of a fact-checking than a review, but whatever. I’m not going to get into a semantic argument. I wrote my first review of this book back in 2012, but after writing it I felt very unsatisfied. GCBC is such a dense book filled with so many unsubstantiated claims that I felt the book demanded a more thorough review. Other bloggers, like James Krieger at Weightology, seem to feel the same way and have tried to provide such a review only to eventually give up once they realize the gravity of the task. I may also give up at some point. I actually have given up a number of times only to feel compelled to hit at least one more chapter.

If you would like to read other parts of this ongoing review go to the table of contents on my Book Reviews page. FYI: All page numbers in this review refer to the hardback version of the book.

Not the Introduction

On pages 60-62 Taubes discusses a publication by the National Academy of Sciences titled Diet and Health: Implications for Reducing Chronic Disease Risk.

I’m not sure that Taubes actually reads it because he gets a few things wrong about it. First (and this is a minor point) he says the publication is thirteen hundred pages long, when in fact it is not even eight hundred pages long. At least that’s the version I have.

Second — and this is probably a more important point — he says about the publication:

It was no longer about the validity of the underlying science, which was no less ambiguous than ever, but about whether Americans should be eating low-fat diets or very low-fat diets.

Actually, Diet and Health recommends a diet of 30% of total calories from fat.1 I don’t see how this could be seen as a low-fat diet, much less a very low-fat diet. Clearly Taubes wants the committee to have recommended something like a very low-fat diet, but they did no such thing so he just lies and says they did anyway. (See: straw man)

Taubes then says:

One striking fact about this evolution is that the low-fat diets now being recommended for the entire nation had only been tested twice… The results of those trials had been contradictory.

Clearly Taubes didn’t bother to actually read Diet and Health. If he did he would have noticed the literally TWENTY-SEVEN PAGES of references regarding dietary fat alone! In fact, the bulk of the publication was devoted to explaining the evidence behind the recommendations. I don’t really blame Taubes for not reading it, though; it was quite long and it didn’t really fit nicely into the narrative he was attempting to craft. As a matter of fact one of the cited trials, titled Low-fat Diet in Myocardial Infarction in The Lancet, had a group consuming about half the percentage of calories from fat than what the National Academy of Sciences was recommending in Diet and Health so the results aren’t really comparable. Nevertheless, the low-fat group actually had beneficial effects to weight and serum lipids compared to the control group.2

* * *

Taubes does some really excellent minimizing on pages 63 and 64 when he discusses some data from the MRFIT trial:

For every one thousand middle-aged men who had high cholesterol—between, say, 240 and 250 mg/dl—eight could expect to die of heart disease over any six-year period. For every thousand men with cholesterol between 210 and 220, roughly six could expect to die of heart disease. These numbers suggest that reducing cholesterol from, say, 250 to 220 would reduce the risk of dying from a heart attack in any six-year period from .8 percent (eight in a thousand) to .6 percent (six in a thousand). If we were to stick rigorously to a cholesterol-lowering diet for thirty years—say, from age forty to seventy, at which point high cholesterol is no longer associated with an increased risk of heart disease—we would reduce our risk of dying of a heart attack by 1 percent.

By the way, I find it humorous that in the previous chapter Taubes was talking about what a disaster the MRFIT trial was, but here he’s discussing it as if it were the capital-T truth.

I think his data is actually wrong, too. He publishes a graph on the same page taken from a MRFIT article, and I think he’s simply guesstimating. The actual data from the trial says that a serum cholesterol value of 220 mg/dl would correspond to a CHD death rate of 5.81/1,000 and a cholesterol value of 250 mg/dl would have a death rate of 9.1/1,000.3,4 I suppose it’s a minor point, but I am going to use the real data in a second.

His choice of how to present the results is a great study of how to deceive with statistics. It also reminds of a scene in Pulp Fiction. You’ve probably seen it, but if you haven’t I’m not going to explain the context because I don’t really need to to make my point.

                                     VINCENT
                         What do you think about what happened 
                         to Antwan?

                                     MIA
                         He fell out of a window.

                                     VINCENT
                         That's one way to say it. Another 
                         way is, he was thrown out. Another 
                         was is, he was thrown out by 
                         Marsellus. And even another way is, 
                         he was thrown out of a window by 
                         Marsellus because of you.

So Taubes says “These numbers suggest that reducing cholesterol from, say, 250 to 220 would reduce the risk of dying from a heart attack in any six-year period from .8 percent (eight in a thousand) to .6 percent (six in a thousand).” That’s certainly one way to say it. Another way is that it reduces your risk of dying from a heart attack by 36%. Another way is it reduces your relative risk of CHD death from 2.88 to 1.84 (with 1.0 being optimal). And even another way to say it is that this data suggests that 205,954 lives in the US could be spared by lowering serum cholesterol from 250 to 220, assuming 20% of the population has cholesterol in excess of 250 mg/dl.

* * *

Page 65-66

Between 1987 and 1994, independent research groups from Harvard Medical School, the University of California, San Francisco, and McGill University in Montreal addressed the question of how much longer we might expect to live if no more than 30 percent of our calories came from fat, and no more than 10 percent from saturated fat, as recommended by the various government agencies. All three assumed that cholesterol levels would drop accordingly, and that this low-fat diet would have no adverse effects, which was still speculation rather than fact.

The Harvard study, led by William Taylor, concluded that men with a high risk of heart disease—such as smokers with high blood pressure—might gain one extra year of life by shunning saturated fat. Healthy nonsmokers, however, might expect to gain only three days to three months. “Although there are undoubtedly persons who would choose to participate in a lifelong regimen of dietary change to achieve results of this magnitude, we suspect that some might not,” the Harvard investigators noted.

The UCSF study, led by Warren Browner, was initiated and funded by the Surgeon General’s Office. This study concluded that cutting fat consumption in America would delay forty-two thousand deaths each year, but the average life expectancy would increase by only three to four months. To be precise, a man who might otherwise die at sixty-five could expect to live an extra month if he avoided saturated fat for his entire adult life. If he lived to be ninety, he could expect an extra four months.* The McGill study, published in 1994, concluded that reducing saturated fat in the diet to 8 percent of all calories would result in an average increase in life expectancy of four days to two months.

Browner reported his results to the Surgeon General’s Office, and only then submitted his article to JAMA. J. Michael McGinnis, the deputy assistant secretary for health, then wrote to JAMA trying to prevent publication of Browner’s article, or at least to convince the editors to run an accompanying editorial that would explain why Browner’s analysis should not be considered relevant to the benefits of eating less fat. “They would have liked it to come out the other way,” explained Marion Nestle, who had edited the Surgeon General’s Report on Diet and Health and had recruited Browner to do the analysis. This put Browner in the awkward position of protecting his work from his own funding agents. As he wrote McGinnis at the time, “I am sensitive to the needs of your office to put forward a consistent statement about what Americans should do, and to your dismay when a project that you have sponsored raises some questions about current policy. I am also concerned that the impacts of recommendations that apply to 240 million Americans are clearly understood. This manuscript estimates the effects of one such recommendation—altering dietary fat intake to 30 percent of calories—based on the assumptions that underlie that recommendation. Shooting the messenger—or creating a smoke screen—does not change those estimates.” JAMA published Browner’s article—“What If Americans Ate Less Fat?”—without an accompanying editorial.

*Browner’s analysis also assumed that restricting dietary fat would reduce cancer deaths, which was speculative then and is even more speculative now.

Although the analysis is perhaps more pessimistic about the benefits of reducing saturated fat, it is also a bit more nuanced than Taubes makes it seem.5 The figures of 42,000 saved lives are in there as is the extra four months of life, but there’s also the following:

The analysis indicates that if those assumptions are valid, restricting dietary fat to a maximum of 30% of total energy intake could reduce CHD mortality rates by between 5% and 20%. Mortality due to cancers of the breast, colon, and prostate might be reduced by an even greater proportion. Similar reductions would also occur in the incidence of these diseases.

AND

From the public health point of view, an increase of 3 months in life expectancy multiplied by 240 million Americans results in about 60 million years of additional life […]

Browner also points out that since the 3-4 month estimate is a statistical average, the real effects of lowering saturated fat would probably translate to several extra years in some individuals and possibly no increased lifespan in others.

But that is not the interesting part… The interesting part is where Taubes states that J. Michael McGinnis tried to shut down the publication of the article. This is based on a letter (presumably) that Browner wrote to McGinnis back then. I have contacted both Dr. Browner and Dr. McGinnis to see if they can confirm this. As of this writing I have received no response from Dr. Browner, but I did receive one from Dr. McGinnis that was very interesting. McGinnis claims he was never contacted by Taubes for his side of the story and that what Taubes wrote “certainly doesn’t ring either familiar or true.” In McGinnis’s own words:

Neither Marion nor I worked in the Surgeon General’s office—rather in a parallel office in HHS—but if the paper was done when she worked with me, it would have been nearly 30 years ago. I really have no recollections on any of what is reported in the passage—including the commissioning of the paper. I do recall the general reported finding on the limited impact on heart disease deaths of the lipid intake reduction indicated, although not the individuals or center (or centers) making the reports. Given the fact that the finding of small effects of isolated dimensions was not unusual (recall MRFIT), it would not have been particularly surprising. It is certainly possible that I would have been of a mind that a narrowcast analysis could be misleading if interpreted as reflecting on the impact of broader associated dietary changes. But unless I was a reviewer commenting on methodologic limits, it would be very unlike me—I cannot recall a single instance—to separately suggest that an article not be published. Indeed, to the contrary, I am squarely in the camp that there is great merit in publicly “calling the question” on these issues to prompt further analytic advances.

Dr. McGinnis also said that he will happily recant if someone were to produce the letter in question. I also contacted Dr. Marion Nestle and she claims that, while she can’t remember the specifics, what Taubes wrote about her remarks are generally true.

* * *

On page 72 Taubes discusses the famous Nurses Health Study and states

In 1992, Willett published the results from eight years of observation of the Nurses cohort. Fifteen hundred nurses had developed breast cancer, and, once again, those who ate less fat seemed to have more breast cancer. In 1999, the Harvard researchers published fourteen years of observations. By then almost three thousand nurses had contracted breast cancer, and the data still suggested that eating fatty foods (even those with copious saturated fat) might protect against cancer.

Walter Willett and Meir Stampfer are two of several authors of these obervational studies.6,7 (Interestingly, Taubes says in a blog post that Willett and Stampfer are not real scientists, they don’t do “real” science, and epidemiology is not to be trusted.) The cited studies do not provide evidence for his claim that copious amounts of saturated fats might protect against cancer. The best thing he can say is that consumption of SATURATED fat doesn’t appear to increase one’s risk of BREAST cancer. Of course the same could also be said of MONOUNSATURATED, POLYUNSATURATED, and even TRANS fats, at least according to these studies.

* * *

On page 73 Taubes gets on the polyunsaturated-fats-cause-cancer bandwagon again stating:

This laboratory evidence that dietary fat caused breast cancer began to evaporate as soon as Diet, Nutrition, and Cancer was published, and researchers could get funding to study it. By 1984, David Kritchevsky, one of the authors of Diet, Nutrition, and Cancer, had published an article in Cancer Research reporting on experiments that had been explicitly designed to separate out the effects of fat and calories on cancer, at least in rats. As Kritchevsky reported, low-fat, high-calorie diets led to more tumors than high-fat, low-calorie diets, and tumor production was shut down entirely in underfed rats, regardless of how fatty their diet was.

However, the results from the study itself are different:8

The data from 3 separate studies altering caloric and fat intake support the conclusions that a high-fat diet influences initiation as well as promotion of DMBA-induced mammary tumorigenesis, that high caloric intake increases tumor yield, and that restriction of caloric intake (even concomitant with the provision of twice as much dietary fat) inhibits tumor formation during the promotion period.

At least he got part of the study correct. By the way, I wonder how Taubes squares this circle in his mind when he later advocates eating all the calories you want — as long as it’s all meat, of course.

* * *

Pg 74

Nonetheless, the pervasive belief that eating fat causes breast cancer has persisted, partly because it once seemed undeniable. Purveyors of health advice just can’t seem to let go of the notion. […] By 2006, with the next release of cancer-prevention guidelines by the American Cancer Society, the ACS was acknowledging that “there is little evidence that the total amount of fat consumed increases cancer risk.” But we were still advised to eat less fat and particularly meats (“major contributors of total fat, saturated fat and cholesterol in the American diet”), because “diets high in fat tend to be high in calories and may contribute to obesity, which in turn is associated with increased risks of cancers.” (Saturated fats, in particular, the ACS added, “may have an effect on increasing cancer risk,” a statement that seemed to be based solely on the belief that if saturated fat causes heart disease it probably causes cancer as well.)

Of course, Taubes ignores the reference in the text that immediately follows “may have an effect on increasing cancer risk” and instead tells his readers that the statement is based on some unfounded belief. In case you’re wondering the reference is a review article that pours over several relevant studies on fat and cancer.9 What Taubes also omits is that the main reasons the ACS recommends avoiding red and processed meats have little to do with fat content.10 I’ll let the ACS explain:

Many epidemiologic studies have examined the association between cancer and the consumption of red meats (defined as beef, pork, or lamb) and processed meats (cold cuts, bacon, hot dogs, etc.). Current evidence supports an increased risk of cancers of the colon and/or rectum and prostate. More limited evidence exists for other sites. Studies that have examined red meat and processed meat separately suggest that risks associated with processed meat may be slightly greater than red meat, but the consumption of both should be limited.

Meat contains several constituents that could increase the risk of cancer. Mutagens and carcinogens (heterocyclic amines and polycyclic aromatic hydrocarbons) are produced by cooking meat at high temperatures and/or by charcoal grilling. The iron content (heme) in red meat may generate free radicals in the colon that damage DNA. Substances used to process meat (nitrates/nitrites and salt) contribute to the formation of nitrosamines that can damage DNA. It is also possible that the fat content in meat contributes to risk. For example, foods that are high in fat increase the concentration of secondary bile acids and other compounds in the stool that could be carcinogens or promoters of carcinogenesis.

These cancer properties of red and processed meats have been well-documented over the years. There is a mountain of evidence for them. But of course Taubes has never been one to let evidence ruin a good story about how people that disagree with him are pinheaded schmucks.

* * *

Pg 75, Taubes lies about the results when discussing a study by the Women’s Health Initiative claiming that

The women on the diet also consumed fewer calories—averaging 120 calories a day less than the controls over the eight years of the study.*

*They did not, however, lose any weight because of this, which is paradoxical, and an issue we will discuss later.

Actually, everyone on the diet lost a significant amount of weight.11

See Taubes response #4

* * *

On page 84 Taubes discusses the results of a Cochrane review*:

The review concluded that the diets, whether low-fat or cholesterol-lowering, had no effect on longevity and not even a “significant effect on cardiovascular events.”

The first part of that claim is actually true. The second lies about the results of the systematic review. It actually reduced cardiovascular events by 16%. The same authors published the Cochrane results in BMJ and they concluded then12:

The findings on cardiovascular events are broadly in keeping with benefits that might be expected from modest lowering of cholesterol concentration and certainly provide support, at an individual level, for the central role of dietary fat intake in the causation of cardiovascular disease.

The results also indicated a reduction in mortality by 9%, but that figure was within the 95% CI. In any case, if you’re curious about the updated results they are basically unchanged.13 From the 2012 Cochrane review:

Dietary change to reduce saturated fat and partly replace it with unsaturated fats appears to reduce the incidence of cardiovascular events, but replacing the saturated fat with carbohydrate (creating a low fat diet) was not clearly protective of cardiovascular events (despite small improvements in weight, body mass index, total and LDL cholesterol).The protective effect was seen almost exclusively in those who continue to modify their diet over at least two years, and in studies of men (not those of women). Dietary advice to those at high risk of cardiovascular disease (particularly where lipid lowering medication may not be available), and probably also to lower risk population groups, should continue to include dietary fat modification, possibly as part of a Mediterranean dietary pattern, and it should be stressed that this is a permanent pattern of eating.

*Something Taubes holds in high regard, unless of course a result might contradict his thesis (as is the case with a Cochrane review of salt and hypertension) in which case they are meaningless. But more on that later.

See Taubes response #5

cloud

1. National Academy Press. Diet and Health: Implications for Reducing Chronic Disease Risk. (1989). at <http://www.nap.edu/openbook.php?record_id=1222&gt;

2. A Research Committee. Low-fat Diet in Myocardial Infarction: A Controlled Trial. The Lancet 286, 501–504 (1965).

3. Martin, M. J., Browner, W. S., Hulley, S. B., Kuller, L. H. & Wentworth, D. Serum cholesterol, blood pressure, and mortality: implications from a cohort of 361,662 men. The Lancet 328, 933–936 (1986).

4. Stamler J, Wentworth D & Neaton JD. Is relationship between serum cholesterol and risk of premature death from coronary heart disease continuous and graded?: Findings in 356 222 primary screenees of the multiple risk factor intervention trial (MRFIT). JAMA 256, 2823–2828 (1986).

5. Holmes, M. D. et al. Association of dietary intake of fat and fatty acids with risk of breast cancer. JAMA 281, 914–920 (1999).

6. Browner WS, Westenhouse J & Tice JA. What if americans ate less fat?: A quantitative estimate of the effect on mortality. JAMA 265, 3285–3291 (1991).

7. Willett, W. C. et al. Dietary fat and fiber in relation to risk of breast cancer. An 8-year follow-up. JAMA 268, 2037–2044 (1992).

8. Kritchevsky, D., Weber, M. M. & Klurfeld, D. M. Dietary Fat versus Caloric Content in Initiation and Promotion of 7,12-Dimethylbenz(a)anthracene-induced Mammary Tumorigenesis in Rats. Cancer Res. 44, 3174–3177 (1984).

9. Kolonel, L. N. Fat, meat, and prostate cancer. Epidemiol. Rev. 23, 72–81 (2001).

10. Kushi, L. H. et al. American Cancer Society Guidelines on Nutrition and Physical Activity for cancer prevention: reducing the risk of cancer with healthy food choices and physical activity. CA. Cancer J. Clin. 56, 254–281; quiz 313–314 (2006).

11. Howard, B. V. et al. Low-fat dietary pattern and weight change over 7 years: the Women’s Health Initiative Dietary Modification Trial. JAMA 295, 39–49 (2006).

12. Hooper, L. et al. Reduced or modified dietary fat for preventing cardiovascular disease. Cochrane Database Syst. Rev. Online CD002137 (2001). doi:10.1002/14651858.CD002137

13. Hooper, L. et al. in Cochrane Database Syst. Rev. (The Cochrane Collaboration) (John Wiley & Sons, Ltd, 2012). at <http://doi.wiley.com/10.1002/14651858.CD002137.pub3&gt;

Good Calories, Bad Calories: A Critical Review; Chapter 2 – The Inadequacy of Lesser Evidence

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Introduction

This is something of an ongoing review, chapter by chapter, of Gary Taubes’s extraordinarily dense book Good Calories, Bad Calories, which I usually shorten to GCBC. You might even consider this more of a fact-checking than a review, but whatever. I’m not going to get into a semantic argument. I wrote my first review of this book back in 2012, but after writing it I felt very unsatisfied. GCBC is such a dense book filled with so many unsubstantiated claims that I felt the book demanded a more thorough review. Other bloggers, like James Krieger at Weightology, seem to feel the same way and have tried to provide such a review only to eventually give up once they realize the gravity of the task. I may also give up at some point. I actually have given up a number of times only to feel compelled to hit at least one more chapter.

If you would like to read other parts of this ongoing review go to the table of contents on my Book Reviews page. FYI: All page numbers in this review refer to the hardback version of the book.

Not the Introduction

Page 24:

The press also played a critical role in shaping the evolution of the dietary-fat controversy by consistently siding with proponents of those who saw dietary fat as an unneccessary evil. These were the researchers who were offering specific, positive advice for the health-conscious reader—eat less fat, live longer. The more zealously stated, the better the copy. All the skeptics could say was that more research was necessary, which wasn’t particularly quotable. A positive feedback loop was created. The press’s favoring of articles that implied Keys’s hypothesis was right helped convince the public; their belief in turn would be used to argue that the time had come to advise cholesterol-lowering diets for everyone, thus further reinforcing the belief that this advice must be scientifically defensible.

There is no proof for this entire paragraph. None. This is just hyper-biased conjecture.

* * *

On page 24 Taubes misquotes an American Heart Association official

 In 1964, when the study still hadn’t taken place, a director of the AHA described its purpose as the equivalent of merely “dotting the final i” on the confirmation of Keys’s hypothesis.

The Wall Street Journal article, from which this is taken, quotes the AHA director as saying something similar, but a different statement with a different meaning.1 There is also no mention of Keys. From the article:

A director of the heart group explained yesterday the association decided to make the recommendation because heart disease is becoming such “a pressing public health problem.” Efforts to stem heart disease “just can’t be left until the last i is dotted and the last t is crossed,” he explained.

* * *

On page 25:

In 1957, Keys insisted that “each new research adds detail, reduces areas of uncertainty, and, so far, provides further reason to believe” his hypothesis. This is known technically as selection bias or confirmation bias; it would be applied often in the dietary-fat controversy. The fact, for instance, that Japanese men who lived in Japan had low blood-cholesterol levels and low levels of heart disease was taken as a confirmation of Keys’s hypothesis, as was the fact that Japanese men in California had higher cholesterol levels and higher rates of heart disease. That Japanese men in California who had very low cholesterol levels still had more heart disease than their counterparts living in Japan with similarly low cholesterol was considered largely irrelevant.

Damn this Keys fellow is so insistent! Does he have to insist literally everything? All kidding aside, the Japanese men in California study he cites was published in 1975. Yet Keys was apparently ignoring that evidence in 1957. Was Keys a person from the future who traveled back in time to the 50s to ignore research that had yet to be published?

Going back to the study that Taubes cites here you will find that it is an observational, cross-sectional study. (Keep that in mind because peppered throughout the book and in a recent blog post he essentially claims that all observational studies are meaningless.) Not only that but the researchers also measured other risk factors beside cholesterol, namely hypertension. Turns out that Japanese Californians also had more hypertension than their Japanese brethren, and hypertension is another major risk factor for coronary heart disease.

I can hear people screaming right now “SEE? This only proves the point that heart disease is caused by other things!” 1) No one is claiming that cholesterol is the sole cause of heart disease. Many things are considered risk factors: smoking, hypertension, cholesterol, diabetes, obesity, etc. Of course that doesn’t prove that cholesterol is not a risk factor. 2) This study is a cross-sectional study so it can’t measure causes, only associations. Taubes beats this drum later.

* * *

Pg 25-26:

The Masai nomads of Kenya in 1962 had blood-cholesterol levels among the lowest ever measured, despite living exclusively on milk, blood, and occasionally meat from the cattle they herded. Their high-cholesterol diets supplied nearly three thousand calories a day of mostly saturated fat. George Mann, an early director of the Framingham Heart Study, examined the Masai and concluded that these observations refuted Keys’s hypothesis. […] To explain away Mann’s research on the Masai, Keys then evoked more recent research suggesting that the Masai, living in nomadic isolation for thousands of years, must have somehow evolved a unique “feedback mechanism to suppress endogenous cholesterol synthesis.” This mechanism, Keys suggested, would bestow immunity on the Masai to the cholesterol-raising effects of fat.

HA HA!! Keys is such an idiot! Does he actually think that humans are capable of developing traits over time that help them adapt and survive in their environment?? A unique “feedback mechanism to suppress endogenous cholesterol synthesis. Is he serious? That’s almost as absurd as some Europeans developing a gene to digest lactose! That’s about as ridiculous as saying that some people have a gene that produces normal alcohol dehydrogenase, while other people of mainly Asian descent have a variant of the gene that codes for an enzyme that metabolizes alcohol differently. Could you imagine? Keys, don’t you understand that you sound like a jackass when saying these things? That’s almost as foolish as saying one could inherit genes that produce more melanin in the skin to protect from the sun’s UV radiation. How preposterous would that be! Oh… wait…

All sarcasm aside, the Masai do seem to be a unique bunch. Evidently much of their diet is raw, unrefrigerated milk, some sort of tea/stew made from the bark of a local tree, and some blood for good measure. I read the study Taubes cited and it’s a strange one. Take note that it is also an observational, cross-sectional study.2 First of all, Mann claims he had trouble recording the diet:

The accurate measurement of dietary intake of these people proved extraordinarily difficult. We were able to make only limited measurements. This difficulty is because of the erratic intake of food, there being no fixed meal patterns in the families, because there are no uniform units of measurement or utensils and because of the disruption of usual behavior in the presence of an observer.

It seems he mainly relies on urine samples to estimate the protein intake of the Masai. Moreover, atherosclerosis was estimated by looking at ECG graphs. That’s odd, right? How accurate is that? In any case, Mann estimated very little atherosclerosis in the Masai. Cholesterol levels were made using the usual method, and they were indeed low.

So the Masai had low cholesterol levels and low atherosclerosis. Makes sense. The only thing that doesn’t really fit is thinking about a diet ostensibly high in saturated fat and cholesterol, but one that doesn’t lead to high serum cholesterol. As Mann put it, there can be one of two explanations: “Either such a diet does not in fact contribute to those consequences or the Masai have some other protecting mechanism which allows them to eat these foods with immunity.”

As it turns out the Masai do have such a protective mechanism as was demonstrated by a controlled feeding study published in the New England Journal of Medicine.3,4 I’ll quote from the abstract:

The Masai of East Africa exhibit some unique biologic characteristics. Despite their customary diet comprised of 66 per cent calories as fat, they have persistent low serum cholesterol and beta-lipoprotein levels. Post-mortem examinations provided direct proof of a paucity of atherosclerosis. Metabolic studies revealed that the Masai absorbed large amounts of dietary cholesterol, but also possessed a highly efficient negative feedback control of endogenous cholesterol biosynthesis to compensate for the influx of dietary cholesterol. Two unusual serum-protein patterns were observed: the presence of a double alpha2 band; and a high level of serum IgA that is apparent at an early age (four years). The high ratios of phospholipid to cholesterol in their gallbladder bile explain the extreme rarity of cholesterol gallstones. All these characteristics may reflect a long-term biologic adaptation of the tribe.

Hm. I guess both Darwin and Keys were right. Natural selection exists after all. However, Mann published another study some years after his ’64 study on the Masai. This one actually examined the hearts and aortae of recently deceased Masai (average age: 38). This newer study now claimed that the Masai actually had “extensive atherosclerosis” but for some reason the Masai’s blood vessels enlarge as they age to compensate for the blockage.5 Now I don’t know what to think about these people, except that they are indeed unique.

* * *

On page 27 Taubes discusses some early data from the Framingham Heart Study, noting that according to some results high serum cholesterol levels did indeed confer about a 5X greater risk of coronary heart disease.6 “But,” he says “there were caveats.”

As the men aged, those who succumbed to heart disease were ever more likely to have low cholesterol (as had Eisenhower) rather than high cholesterol. The cholesterol/heart-disease association was tenuous for women under fifty, and nonexistent for women older. Cholesterol has “no predictive value,” the Framingham investigators noted in 1971. This means women over fifty would have no reason to avoid fatty foods, because lowering their cholesterol by doing so would not lower their risk of heart disease. None of this was deemed relevant to the question of whether Keys’s hypothesis was true.

Talk about selection bias! This has to be one of the most selective readings of that study. The actual text says that serum cholesterol was highly predictive of heart disease.7 Lemme give you a few more quotes from that study that Taubes missed:

  • An increased risk proportional to antecedent serum cholesterol was found whether or not it was associated with elevated Sf20-400 prebeta lipoprotein.
  • When adjustment was made for the concomitant prebeta lipoprotein concentration and other factors related both to coronary heart disease risk and to blood lipids, a residual gradient of coronary heart disease risk proportional to the serum cholesterol was still evident.
  • Risk of coronary heart disease in men can be estimated using any of the lipids evaluated; however, none proved more useful than an accurate total serum cholesterol.
  • Cholesterol, as indicated by the size of the coefficient in Table 2, carries most of the weight as a contributor to coronary heart disease in men, whether manifested as angina or some more serious form of the disease.
  • Risk of each particular clinical manifestation of coronary heart disease (including angina, myocardial infarction, and sudden death) proved proportional to the antecedent serum cholesterol level in men of all ages studied.
  • In men and younger women the risk simply rose in proportion to the antecedent serum cholesterol concentration from the lowest to highest values recorded in this population sample (Figure 3). There was nothing to suggest that some particular level was “critical.” Hence, it does not appear logical to examine the relation of cholesterol to risk of coronary heart disease in terms of “hypercholesterolemia” but rather in terms of the actual concentration of cholesterol in the plasma.
  • Examination of the risk of developing coronary heart disease according to the actual serum cholesterol concentration of each subject grouped into quartiles showed an increase in risk proportional to the antecedent cholesterol concentration, not only in the general population but in persons free of factors believed associated both with hypercholesterolemia and with coronary heart disease
  • Even after excluding persons with hypertension, diabetes. ECG abnormalities, and the cigarette habit, a distinct gradient of risk proportional to the cholesterol concentration can be demonstrated. This tends to brand the lipid, not associated variables, as the culprit. As shown in an earlier analysis, a net effect of cholesterol is clearly apparent in men of all ages
  • According to this analysis the dominant effect was assigned to serum cholesterol, with an insignificant contribution of the other lipids It is apparent that in men cholesterol accounts for more of the total distance between those who developed and those who remained free of the disease than does Sf20-400 prebeta lipoprotein in all but the oldest subjects.
  • For cholesterol in men a strong residual effect remains after accounting for the level of Sf20-400 lipoprotein and the other factors In younger, but not older, women distinctly higher cholesterol values may also contribute independently to risk
  • Of all the identified host factors associated with increased susceptibility to coronary heart disease, the blood lipids are among the strongest.
  • If there is in fact a single common denominator through which the multiple interrelated predisposing factors in coronary heart disease operate, an abnormal accumulation or handling of blood lipids would appear the most likely candidate.
  • These investigators have found significant differences in the blood content of a variety of lipids and have implicated the total fasting triglyceride, beta and prebeta lipoprotein, alpha to beta cholesterol ratio, cholesterol to phospholipid ratio, and fatty acids
  • There were 6 xanthomatous individuals in the Framingham population sample of 5,127 men and women. All had serum cholesterol values exceeding 400 mg/100 ml and a strong family history of coronary heart disease, and within the follow-up period all six died of coronary heart disease before their fiftieth birthdays.
  • Any one of the lipids or lipoproteins examined, and, by inference, a triglyceride as well, can be used effectively for assessing vulnerability to coronary heart disease. None, however, would appear superior to the more convenient serum cholesterol determination for this purpose.
  • In women, however, the picture appears to be somewhat different. In women under the age of 50, as in men, high cholesterol values and not Sf20-400 prebeta lipoprotein appear to be associated with an increased risk. In older women, on the other hand, cholesterol appears to have no predictive value, and Sf20-400 prebeta lipoprotein actually appears to be superior to cholesterol for estimating risk.
  • The data presented suggest that in men the moderately elevated cholesterol values commonly encountered in the general population, regardless of the metabolic aberration responsible or how it is transported or partitioned among the lipoproteins, are associated with increased risk of coronary heart disease.

In case you were wondering, pre-beta lipoprotein is now called very low density lipoprotein (VLDL) which is similar to LDL and HDL in that it transports triglycerides and cholesterol through the blood. How anyone can read that study and only come away with cholesterol values in women over 50 doesn’t make much difference is really missing the point of the whole damn study. Especially when you consider what is very predictive of heart disease in women over 50 is a protein that transports lipids through the blood.

Here’s a simple chart from the article that shows the risk of heart disease on those with high serum cholesterol. FYI: Anything above a 1.0 means an increased risk. A 1.0 means no risk. Less than 1.0 means reduced risk. So a 2.0 would indicate a two-fold risk increase, 3.0 would be three times the risk, etc.

Serum Cholesterol, Lipoproteins, and the Risk of Coronary

* * *

On page 27 Taubes mentions the Western Electric study but again leaves out important data that runs contrary to his thesis.

Two decades later, Jeremiah Stamler and his colleague Richard Shekelle from Rush–Presbyterian–St. Luke’s Medical Center in Chicago revisited Western Electric to see how these men had fared. They assessed the health of the employees, or the cause of death of those who had died, and then considered the diets each subject had reportedly consumed in the late 1950s. Those who had reportedly eaten large amounts of polyunsaturated fats, according to this new analysis, had slightly lower rates of coronary heart disease, but “the amount of saturated fatty acids in the diet was not significantly associated with the risk of death from [coronary heart disease],” they reported.

Immediately prior to the quoted phrase is a sentence that Taubes probably doesn’t want in his narrative so it is left out. I have reproduced it below.8 Bolding is mine.

When the risk of death from CHD was analyzed in terms of the component dietary variables, it was inversely related to intake of polyunsaturated fatty acids and positively related to intake of dietary cholesterol.

* * *

Taubes spills some ink on discussing a major dietary trial called the Anti-Coronary Club Trial on page 36:

The first and most highly publicized was the Anti-Coronary Club Trial, launched in the late 1950s by New York City Health Department Director Norman Jolliffe. The eleven hundred middle-aged members of Jolliffe’s Anti-Coronary Club were prescribed what he called the “prudent diet,” which included at least one ounce of polyunsaturated vegetable oil every day. The participants could eat poultry or fish anytime, but were limited to four meals a week containing beef, lamb, or pork. This made Jolliffe’s prudent diet a model for future health-conscious Americans. Corn-oil margarines, with a high ratio of polyunsaturated to saturated fat, replaced butter and hydrogenated margarines, which were high in saturated fats. In total, the prudent diet was barely 30 percent fat calories, and the proportion of polyunsaturated to saturated fat was four times greater than that of typical American diets. Overweight Anti-Coronary Club members were prescribed a sixteen-hundred-calorie diet that consisted of less than 20 percent fat. Jolliffe then recruited a control group to use as a comparison.

I’m gonna talk about what some might consider a minor point, but to me is significant. It is about rhetoric and word choice, so if you think this is petty and boring please skip ahead. What struck me was this: “In total, the prudent diet was barely 30 percent fat calories…” Barely? 30% of total calories as fat is smack dab in the middle of normal for most people. It’s nowhere near what anyone would consider a low fat diet. Yet Taubes uses the word “barely” to modify the 30% figure. Webster defines “barely” as “in a meager manner,” yet there is really nothing meager about eating a diet of 30-33% fat as it was stated in the actual study.9

As I have stated before and will no doubt state again, this is an example of when, if Taubes doesn’t blatantly misrepresent the results of a study, he will editorialize the figures in misleading rhetoric.

Let’s keep going with the Anti-Coronary Club Trial.

Jolliffe died in 1961, before the results were in. His colleagues, led by George Christakis, began reporting interim results a year later. “Diet Linked to Cut in Heart Attacks,” reported the New York Times in May 1962. “Special Diet Cuts Heart Cases Here,” the Times reported two years later. Christakis was so confident of the prudent-diet benefits, reported Newsweek, that he “urged the government to heed the club results and launch an educational and food-labeling campaign to change U.S. diet habits.”

The actual data, however, were considerably less encouraging. Christakis and his colleagues reported in February 1966 that the diet protected against heart disease. Anti-Coronary Club members who remained on the prudent diet had only one-third the heart disease of the controls. The longer you stayed on the diet, the more you benefited, it was said. But in November 1966, just nine months later, the Anti-Coronary Club investigators published a second article, revealing that twenty-six members of the club had died during the trial, compared with only six of the men whose diet had not been prudent. Eight members of the club died from heart attacks, but none of the controls. This appeared “somewhat unusual,” Christakis and his colleagues acknowledged. They discussed the improvements in heart-disease risk factors (cholesterol, weight, and blood pressure decreased) and the significant reduction in debilitating illness “from new coronary heart disease,” but omitted further discussion of mortality.

The “somewhat unusual” quote occurs in the first report, and not the second report as Taubes implies. What’s more is that the figures Taubes gives are not correct. The second report discusses deaths not related to heart disease:

Out of the 814 experimental group subjects, there have been 18 known deaths from causes other than coronary heart disease among individuals who had not experienced a new coronary event. This is in comparison to six such deaths out of the 463 individuals in the control group.10

The first report details deaths specifically due to heart disease, which was three in the experimental and zero in the control.9 This is not unusual considering the experimental group began with more risk factors for heart disease compared to the controls, namely greater rates of obesity, hypertension, hypercholesterolemia, etc. The results of the other endpoints (which Taubes surprisingly states, but also kind of minimizes) was that by the end of the trial the non-prudent dieters had significantly higher cholesterol, significantly higher blood pressure, significantly more obesity, and about triple the incidence of heart disease. All of this despite having less risk factors than the prudent group at the beginning of the trial. But I suppose these things aren’t important; what is important, according to Taubes, is the made-up death numbers.

Taubes states that further discussion of mortality was omitted which is clearly false because both reports obviously discuss the deaths in the trial. How do you pull numbers on mortality from the reports and then turn around and claim no discussion on mortality? Moreover, I don’t know what would make the data “less encouraging.” Considerably less encouraging for Taubes’s meat-heavy narrative, perhaps. The results are pretty consistent with the other similar dietary trials that Taubes tries to spin.

* * *

Pg 37 Taubes discusses another dietary study:

In July 1969, Seymour Dayton, a professor of medicine at the University of California, Los Angeles, reported the results of the largest diet-heart trial to that date. Dayton gave half of nearly 850 veterans residing at a local Veterans Administration hospital a diet in which corn, soybean, safflower, and cottonseed oils replaced the saturated fats in butter, milk, ice cream, and cheeses. The other half, the controls, were served a placebo diet in which the fat quantity and type hadn’t been changed. The first group saw their cholesterol drop 13 percent lower than the controls; only sixty-six died from heart disease during the study, compared with ninety-six of the vets on the placebo diet.

Only 66 died on the unsaturated fat diet while 96 died on the saturated fat diet? That’s only a difference of 30 lives! It’s 31% fewer deaths. Practically nothing, right? Barely a difference at all. By the way, in case you’re interested there are a few pertinent facts that Taubes left out (yet again). I have reproduced it below. Remember the control group was high in saturated animal fat, and the experimental group was high in unsaturated fats from plants.11

The number of men sustaining events in major categories, in the control and experimental groups, respectively, was: definite silent myocardial infarction, 4 and 9; definite overt myocardial infarction, 40 and 27; sudden death due to coronary heart disease, 27 and 18; definite cerebral infarction, 22 and 13. The difference in the primary end point of the study-sudden death or myocardial infarction was not statistically significant. However, when these data were pooled with those for cerebral infarction and other secondary end points, the totals were 96 in the control group and 66 in the experimental group; P = 0.01. Fatal atherosclerotic events numbered 70 in the control group and 48 in the experimental group; P < 0.05. Life-table analysis in general confirmed these conclusions. For all primary and secondary end points combined, eight year incidence rates were 47.7% and 31.3% for the control and experimental groups, respectively; P value for the difference between the two incidence curves was 0.02.

If you don’t want to read the above block quote, I’ll summarize it for you: in all but one endpoint that was measured the experimental diet of unsaturated fats had less overt myocardial infarction, sudden death, cerebral infarction, fatal atherosclerotic events, etc. And not by a tiny margin – a significant margin.

The next paragraph Taubes states:

Thirty-one of the men eating Dayton’s experimental cholesterol-lowering diet, however, died of cancer, compared with only seventeen of the controls. The risk of death was effectively equal on the two diets. “Was it not possible,” Dayton asked, “that a diet high in unsaturated fat…might have noxious effects when consumed over a period of many years? Such diets are, after all, rarities among the self-selected diets of human population groups.” Because the cholesterol-lowering diet failed to increase longevity, he added, it could not provide a “final answer concerning dietary prevention of heart disease.”

What’s interesting is the the authors’ statement Taubes quotes from the paper. I want to make something clear: Taubes introduces the author and gives a brief background of the trial. Then he relates the conditions and methods of the study, then he cherry-picks one of the myriad results. In the next paragraph Taubes then gives his interpretation of the results, and tells you why he thinks the results were pretty much a wash. ONLY AFTER ALL THAT Taubes then reproduces a couple sentences from the journal article questioning whether a diet of unsaturated fat might have “noxious effects” presumably because of the study results. What Taubes likely wants the reader of GCBC to think is that after the results of the study are in and the numbers have been crunched and the data has been analyzed, Dr. Seymour Dayton is sitting at his desk and ruminating on what could have produced these results. As if he is asking a rhetorical question or providing a hypothesis for a future dietary trial.

What the reader of GCBC does not know is that Dayton asks this question in the introduction of the text, then later will explicitly answer this very question with his own data. Do you want to know if the experimental diet has noxious effects? Well there’s a section in the results portion of the study titled “Does the Experimental Diet Have Noxious Effects?” where Dr. Dayton states:

As indicated in table 29 and discussed in some detail above, the excess mortality in nonatherosclerotic categories was not sufficiently impressive to justify the conclusion that harmful effects had been demonstrated.

AND

One may also wonder whether the experimental diet may have exerted its effect on mortality data primarily by accelerating nonatherosclerotic deaths (see table 28), decreasing the atherosclerotic mortality by inducing early death due to other cause. Such a mode of action would be associated with higher numbers of deaths in the experimental group compared with the controls, whereas the reverse was true in this trial (fig. 13).

AND

The other observation which raised some question of a possible toxic effect was the low arachidonic acid concentrations in atheromata of long-term, high-adherence subjects on the experimental diet (tables 37 to 40). For reasons already cited, this may be more appropriately viewed as evidence of a salutary rather than a toxic effect.

I’d like to take this opportunity to mention that this is one of the many examples that shows that Taubes is not merely mistaken, but he is working very hard to quite literally deceive his readers. The numbers he cites as deaths from cancer is likely an honest citation error – no one could possibly know. But when you think about the information he presents it is evident that he read this text very carefully and thoroughly, yet only included the bits that he could spin to fit his narrative. With this text and many, many others he explicitly does not mention the very relevant information that runs contra to his nutritional ideology. He is essentially in the marketing business; marketing the low-carb religion rather than informing readers. It’s as if a movie critic were to review a film and write “Whoever was involved in making this film should be put in a gas chamber,” and the film’s marketer took the review and wrote “A gas!” on the movie poster.

Okay, I think I’ve made my point. Moving on…

Go to Good Calories, Bad Calories: A Critical Review; Chapter 3 – Creation of Consensus

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Refs

1. Heart Association Stirs Up a Controversy By Urging Public to Alter Intake of Fats. Wall Str. J. 1923 – Curr. File 6 (1964).

2. Mann, G. V. et al. Cardiovascular disease in the masai. J. Atheroscler. Res. 4, 289–312 (1964).

3. Ho, K. J., Biss, K., Mikkelson, B., Lewis, L. A. & Taylor, C. B. The Masai of East Africa: some unique biological characteristics. Arch. Pathol. 91, 387–410 (1971).

4. Taylor, C. B. & Ho, K.-J. Studies on the Masai. Am. J. Clin. Nutr. 24, 1291–1293 (1971).

5. Mann, G. V., Spoerry, A., Gray, M. & Jarashow, D. Atherosclerosis in the Masai. Am. J. Epidemiol. 95, 26–37 (1972).

6. Dawber, T. R., Kannel, W. B., Revotskie, N. & Kagan, A. The Epidemiology of Coronary Heart Disease–The Framingham Enquiry. Proc. R. Soc. Med. 55, 265–271 (1962).

7. Kannel, W. B., Castelli, W. P., Gordon, T. & McNamara, P. M. Serum Cholesterol, Lipoproteins, and the Risk of Coronary Heart Disease: The Framingham Study. Ann. Intern. Med. 74, 1–12 (1971).

8. Shekelle, R. B. et al. Diet, Serum Cholesterol, and Death from Coronary Heart Disease. N. Engl. J. Med. 304, 65–70 (1981).

9. Christakis G, Rinzler SH, Archer M & Kraus A. Effect of the anti-coronary club program on coronary heart disease risk-factor status. JAMA 198, 597–604 (1966).

10. Christakis, G. et al. The anti-coronary club. A dietary approach to the prevention of coronary heart disease–a seven-year report. Am. J. Public Health Nations Health 56, 299–314 (1966).

11. Dayton, S., Pearce, M. L., Hashimoto, S., Dixon, W. J. & Tomiyasu, U. A Controlled Clinical Trial of a Diet High in Unsaturated Fat in Preventing Complications of Atherosclerosis. Circulation 40, II–1 (1969).

Eggs and Heart Disease

[Eggs and Heart Disease mp3]

What’s the deal with eggs?

It seems that some foods like eggs and margarine are on a perpetual pendulum with the media and, by extension, public opinion. Some days the egg is vilified as a harbinger of heart disease, while other days everything is coming up roses for the little guy. Case in point: Here is a recent article from a local Charleston news station stating

A new study suggests just three egg yolks per week can accelerate heart disease almost as much as smoking.

This article is based off a recent study from Canada published in the journal Atherosclerosis.1 Contrast this with the Harvard School of Public Health’s official position on eggs:

Recent research has shown that moderate egg consumption—up to one a day—does not increase heart disease risk in healthy individuals and can be part of a healthy diet.

So which is it? Three eggs a week is as bad as smoking or one egg per day is perfectly healthy? It cannot be both. So what should we believe?

As of now the link between serum cholesterol2 and heart disease is about as near to a capital-F Fact as you get in nutrition science.  So when you hear that eggs are really high in cholesterol compared with most other foods commonly consumed in the United States, one logical conclusion you could draw from this (if you eat a fair amount of eggs) is the following: If I stop eating eggs I will reduce my risk of heart disease. However, the waters of truth become muddier when you try to examine the actual science behind this bit of conventional wisdom.

Lucky for us my colleague Carrie Dennett did most of the leg work and found the best research available on the subject. What follows is adapted from her research.

Epidemiological Studies

  • An analysis of data from the Framingham Heart Study in 1982 was one of the first epidemiological studies to suggest that there was no significant association between egg consumption and coronary heart disease (CHD), myocardial infarction, or all-cause mortality.3
  • The “Harvard Egg Study” looked at the association between egg consumption and the risk of CHD in two prospective cohorts, the Health Professionals Follow-up Study and the Nurses’ Health Study. After adjustment for age, smoking and other CHD risk factors, there was no significant association between recent or long-term consumption of up to 1 egg per day and risk of CHD or stroke. However, subjects with existing hypercholesterolemia, cardiovascular disease, diabetes, or cancer were excluded from analysis.4
  • Djousse and Gaziano examined the association between egg consumption and CVD and total mortality among 21,327 participants from the Physicians’ Health Study I. The authors concluded that consumption of up to 6 eggs per week does not influence the risk of myocardial infarction, stroke, or total mortality in healthy U.S. male physicians.5 Individuals who ate beyond six eggs per week, however, did see an increase in CVD risk.
  • Data from the First National Health and Nutrition Examination Survey (NHANES-1) and the NHANES-1 Epidemiological Follow-up Study (NHEFS) was examined and a multivariate analysis found no significant difference in the relative risk of incident stroke, ischemic stroke, coronary artery disease (CAD) and mortality between low (1 egg/week or less), moderate (1-6 eggs/week), and high egg consumers (greater than 6 eggs/week).6 One important exception were high-egg-consuming diabetics who had twice the normal risk of CAD.
  • The Japan Public Health Center-based prospective study on cancer and CVD, which involved 90,735 men and women (ages 40-69), found no association between almost daily egg consumption and CHD incidence.7
  • Researchers in Spain looked at egg consumption among 14,185 subjects from the prospective cohort participating in the SUN (Seguimiento Universidad de Navarra) Project and found no association between the highest level of egg consumption (greater than 4 eggs/week) and the lowest (less than 1 egg/week).8

All of the above studies suggest that eggs are relatively benign and have little effect on one’s risk of cardiovascular disease. However, there would have to be at least a few that show some detrimental associations of eggs. After all, the well-ingrained idea that eggs are risky business has to be more than just a hunch, right? And indeed there are a handful of such studies.

  • Australian Aborigines were followed from 1988-89 to 2002 and it was found that consumption of 2+ eggs per week was associated with a 2.6-fold increased risk of CHD.9
  • A prospective study of 10,802 men and women in the United Kingdom found a 2.7-fold increased risk of death among subjects who consumed 6 or more eggs per week.10

However, Carrie notes in the podcast that the authors of the first paper did not collect information on fruit and vegetable intake and thus were unable to determine if there was an inverse association between high fat consumption and low intake of fruits and vegetables. Furthermore, the authors of the second paper used a food frequency questionnaire (FFQ) that was validated only for fiber intake. This means it has been shown that the FFQ they used measures fiber intake fairly accurately, but it has not been proven that it can do the same for other nutrients.

Controlled Trials

It was noted in the podcast that hyperlipidemic individuals are usually excluded from major studies like these. An exception that we discussed was a randomized, placebo-controlled crossover trial of 40 hyperlipidemic adults by Njike et al.11 Study subjects were randomly assigned to daily consumption of two hardboiled eggs or egg substitute for six weeks, separated by a 4-week washout. They found that egg consumption did not have a detrimental effect on endothelial function or plasma lipids. What was interesting, though, was that the egg substitute group showed a significant improvement in endothelial function, total cholesterol, and LDL cholesterol. Similar results were seen in an identically structured study by Katz et al that used treatment with daily consumption of either two eggs or oats for 6 weeks by 50 healthy men and women (mean age 56 years).12

Carrie also mentioned a study involving hyper- and hyporesponders13 of dietary cholesterol. A randomized crossover trial in Mexico examined the effect of dietary cholesterol from eggs.14 The subjects (30 boys and 30 girls aged 8-12 years) were randomly assigned to eat either two whole eggs or egg substitute for 30 days, with a three-week washout period. Each child was then classified as a hyperresponder or hyporesponder based on their degree of plasma cholesterol response. The hyperresponders had an increase in LDL and HDL cholesterol during the period of whole egg consumption, with the LDL:HDL ratio remaining the same. Hyporesponders had no significant alterations to LDL or HDL.

Of course now we get into even more complicated waters when we include discussions of not just total cholesterol but also LDL:HDL ratios. The previous study even mentions differentiating the small, dense LDL particles from larger, more buoyant LDL particles. There is actually a big difference between the two types, with the former more strongly linked to the heart diseases that we all want to try and avoid. But that is perhaps a topic for another day.

Choline

Carrie also brought up the fact that eggs were a major dietary source of choline. However, we were both having some trouble trying to remember what good non-animal sources of choline were available to vegetarians and vegans. Luckily Wikipedia never disappoints.15 Vegans should have no trouble incorporating some of those foods into their diet. Although, on a gram-for-gram basis eggs seem to be a good way to go, otherwise you’ll have to eat an entire pound of spinach to get a similar amount of choline that one egg’ll give ya.

Bottom Line

Eating a few eggs a week is not likely to increase your risk of heart disease, especially if you’re already healthy. On the other hand, if you have diabetes or some other metabolic disorder such as hyperlipidemia or hypercholesterolemia you should be mindful of how many eggs you are eating in a given week. You may need to limit your egg consumption to only 1 or 2 per week. In any case, discuss it with your primary physician.

  1. which is not a fringe journal
  2. the cholesterol circulating in your blood vessels
  3. Dawber TR, Nickerson RJ, Brand FN, et al. Eggs, serum cholesterol, and coronary heart disease. The American Journal of Clinical Nutrition 1982;36(4):617-25.
  4. Hu FB, Stampfer MJ, Rimm EB, et al. A Prospective Study of Egg Consumption and Risk of Cardiovascular Disease in Men and Women. JAMA: The Journal of the American Medical Association 1999;281(15):1387-94.
  5. Djoussé L, Gaziano JM. Egg consumption in relation to cardiovascular disease and mortality: the Physicians’ Health Study. The American Journal of Clinical Nutrition 2008;87(4):964-9.
  6. Qureshi A, Suri M, Ahmed S, et al. Regular egg consumption does not increase the risk of stroke and cardiovascular diseases. Med Sci Monitor 2007;13(1):CR1-8.
  7. Nakamura Y, Iso H, Kita Y, et al. Egg consumption, serum total cholesterol concentrations and coronary heart disease incidence: Japan Public Health Center-based prospective study. British Journal of Nutrition 2006;96(05):921-8.
  8. Zazpe I, Beunza JJ, Bes-Rastrollo M, et al. Egg consumption and risk of cardiovascular disease in the SUN Project. European Journal of Clinical Nutrition 2011;65(6):676-82.
  9. Burke V, Zhao Y, Lee AH, et al. Health-related behaviours as predictors of mortality and morbidity in Australian Aborigines. Preventive Medicine 2007;44(2):135-42.
  10. Mann JI, Appleby PN, Key TJ, et al. Dietary determinants of ischaemic heart disease in health conscious individuals. Heart 1997;78(5):450-5.
  11. Njike V, Faridi Z, Dutta S, et al. Daily egg consumption in hyperlipidemic adults: Effects on endothelial function and cardiovascular risk. Nutrition Journal 2010;9(28).
  12. Katz DL, Evans MA, Nawaz H, et al. Egg consumption and endothelial function: a randomized controlled crossover trial. International Journal of Cardiology 2005;99(1):65-70.
  13. Hyperresonders in this context means those individuals who have an increase in serum cholesterol in proportion to increased dietary cholesterol. Hyporesonders are those individuals that do not see such an increase in serum cholesterol.
  14. Ballesteros MN, Cabrera RM, del Socorro Saucedo M, et al. Dietary cholesterol does not increase biomarkers for chronic disease in a pediatric population from northern Mexico. The American Journal of Clinical Nutrition 2004;80(4):855-61.
  15. That’s not true. I’ve been disappointed by Wikipedia a few times.