Quite a few people have asked for my comments on the Bazzano study Effects of low-carbohydrate and low-fat diets[1] recently reported in the NY Times.[2] Several colleagues who are generally supportive of the whole food plant-based (WFPB) diet have already responded quite well. I have a different response based on my experience. The following introduction is important background for my opinion.
Understanding the evidence claimed for a low carb diet requires understanding its counterpart, the so-called low fat diet, which is the diet against which the low carb diet is being compared. I have previously commented on the low fat diet in another article on our website[3] (https://nutritionstudies.org/fallacious-faulty-foolish-discussion-about-saturated-fat/) based on a NY Times report by O’Connor A Study Questions Fat and Heart Disease Link.[4]
For background, I co-authored the first ‘official’ report that increased interest in the health value of ‘low fat’ diets. This was the 1982 “Diet, Nutrition and Cancer” report of the National Academy of Sciences (NAS)[5], the most sought after report in NAS history. Public interest in that report was unusually intense. The animal-based food industry felt impacted by that report and quickly countered with their own report, Diet, Nutrition and Cancer: A Critique[6] placing a copy on the desk of every U.S. Congress person (House and Senate).
This NAS committee of 13 scientists deliberated at length about what level of dietary fat might be appropriate for good health and settled on a “goal” of 30% or less fat (as a percent of total diet calories), down from the then average of about 40%. But this 30% benchmark was only a suggested goal to encourage the direction of dietary change, which would be consistent with the evidence. An additional goal was to consume more fruits, grains and vegetables. This 30% goal somehow got twisted by those who incorrectly labeled it to be a low fat diet then claimed that it was subsequently tried but did not work.
Some have claimed that the report of the U.S. Senate committee chaired by Senator George McGovern was the first official government report. It was not. It was merely a summary of testimony and in reality was criticized by the scientific community at that time as being without scientific merit. Some of that testimony concerned the association of high fat diets with heart disease, particularly the findings of Ancel Keys and his colleagues.[7] [8]
Although there was no mandate or funding to implement the committee’s findings, it nonetheless encouraged public interest in dietary fat and led the U.S. Senate to appropriate $1 million to have the NAS (through the NIH) summarize the scientific evidence on diet and cancer. At about that same time, the Department of Agriculture and the Department of Health Education and Welfare had begun a partnership to produce the first U.S. Dietary Guidelines. These reports were those that carried the weight of scientific analysis and justified a degree of authority. But most importantly, the 30% dietary fat suggestion was only a goal indicating a direction of change.
Ever since that time, the recommendation on dietary fat has become a major talking point in discussions about diet and health, far more so than it deserves. It is extremely important to note that the 30% fat ‘goal’ of NAS was not intended to be a specific amount of dietary fat that insured freedom from cancer or creation of optimal human health in general. This report clearly stated, “The scientific data do not provide a strong scientific basis for establishing fat intake at precisely 30% of total calories. Indeed, the data could be used to justify an even greater reduction.” The fact that both the 1982 NAS science-based report on cancer and the 1977 McGovern political report on heart disease established the same numerical metric for dietary change had an unintended consequence. It unfortunately and incorrectly inferred dietary fat as a major cause of these diseases. Moreover, the specific fat most discussed as the principal culprit is saturated fat, more commonly found in animal-based foods, a serious challenge for that industry.
Now, let’s return to the recent Bazzano report on the low carb diet[1] which in reality is a high protein, high fat diet. This low carb diet was compared to the so-called ‘low fat’ diet[9] cited by the 1982 NAS report on diet, nutrition and cancer[5] and the early dietary guidelines begun in 1980.[10]
In effect, the low carb (= high fat) concept, as illustrated in this recent study, challenges the goal of improving health by consuming less fat, especially saturated fat. Translated, the goal means reducing the consumption of animal-based foods, the main source of saturated fat. Low carb enthusiasts argue the opposite by advocating diets high in fat and protein, easily provided by animal based foods. But, by using the phrase ‘low carb’, they obtain a more favorable public perspective. They shy from airing their real passion that we should be consuming more animal-based foods, then stir in a little truth, namely, that ‘carbs’ can be problematic. But this ‘problem’ should only refer to refined carbohydrates (sugar, refined white flour), not total carbohydrates that are almost entirely produced in Nature by plants. I make these points because the obvious intent of the low carb enthusiasts is to defend and advocate the consumption of animal-based foods.
Research on the so-called low carb diet is based on an ineffective, superficial hypothesis that is almost never fully explained, as summarized below.
First, the hypothesis that saturated fat is a major cause of these diseases has had a perpetual life, now for more than 100 years, while ignoring evidence to the contrary.
Second, the researchers’ definition of a low fat diet is blatantly false. They assume that a 30% fat diet is low fat, which is not very different from the standard American diet (SAD) at about 35-37% fat. A WFPB diet, a truly low fat diet is around 8-12% fat.
Third, the low carb diet contains very little if any whole plant-based foods, which are the main foods that create health benefits and disease reversals. Tom Campbell MD,
the Executive Director of our non-profit CNS, reviewed the Bazzano report, compared the contents of four nutrients almost exclusively produced in whole plant-based foods (vitamin C, beta carotene, folate and fiber) and, after allowing for the decreased total calorie intakes in both groups, concluded that these plant-specific nutrient intakes did not differ either between these diets or during the 12 months of the study.
Both groups therefore consumed a very low quantity of whole plant-based foods but a very high, excessive quantity of fat and protein, although the low carb group consumed about 30% more fat and protein than the already high levels consumed by the low fat group. There is no way meaningful results could be expected. Worse, the so-called low fat diet not only is not low fat but also is not much different from the diets used by most people using a standard American diet (SAD).
For comparison, Tom Campbell who regularly consumes a WFPB diet, carefully recorded his nutrient intakes for one busy day, recording the following: dietary fiber 71 g/day, carbohydrate 77% of total diet calories, fat 8% of total diet calories, and 15% protein of total diet calories. Bazzano’s “low fat” diet was dietary fiber 16 g/day, carbohydrate 54% of total diet calories, fat 29.8% of total diet calories, and 18.6% protein. Take a second look at these numbers and I think that you will agree that the researchers’ low fat’ is anything but low fat (29.8% vs 8%) while also being very low in fiber 16 vs. 71 g/day. Please, if necessary, take yet another look because this is so typical of those who do so-called research on the low carb diet as it compares with their concocted low fat diet. It is bogus research!
Fourth, I have engaged advocates of the low carb diet in conversation and have been explicitly told that ‘they know what I am saying but, never mind, if they choose to call a 30% fat diet a low fat diet, that is their privilege.’ This may be freedom of speech but it is not honest speech. They refer to the WFPB diet as “extremely” low fat and unpalatable food that no one wants, thus displaying their bias. Another diet comparison report by Gardner[11] investigating the low carb diet actually included, for comparison, a WFPB diet group (called the ‘Ornish’ diet) and referred to it as “extremely low fat” that showed no particular benefit. It was 29% fat, a distortion of the Ornish/WFPB diet. its findings were published in the Journal of the American Medical Association (JAMA) and featured in the NY Times. When four of us, including Ornish, wrote responses to the editor—and such letters are customarily published—we were summarily dismissed. The dismissal of Dr. Ornish’s letter is an obscenity.
And fifth, the clinical metrics obtained for the low carb diet are nothing more than a few random but trivial effects that would be expected when comparing diets 1) that differ little from each other in nutrient and food composition and/or 2) that result from the consistently lower calorie intake of the low carb subjects in this study (calorie intake was 27% lower in the low fat group but 32% lower in the low carb group, a 22% greater reduction for the low carb group—a result completely ignored by the researchers!).
In summary, two dietary characteristics illustrate the problem with this latest study, 1) the low fat diet is not low fat and 2) the consumption of truly healthful whole plant- based foods is very low in both diet groups, with no discernible difference between the diets. Together, these two characteristics negate any possibility of observing meaningful results. Both experimental diets are pro-inflammatory, high in fat and very low in foods that actually create health. In no way does it speak to the health benefits demonstrated by the truly low fat WFPB diet.
If this obvious experimental flaw is not convincing enough, consider this. Dietary fat—and especially saturated fat—has long been said to be the major macronutrient most responsible for cardiovascular disease and cancer. I personally remember well during the 1950s when, on our farm, word came that fat might be a health problem, although I knew not why this was so. During the 1960s and 1970s, research findings were appearing to show very impressive correlations between dietary fat and breast and colon cancers and heart disease. And it was saturated fat, much richer in animal based foods, that was believed to be chiefly to blame. Word spread to consume low fat milk and lean cuts of meat in order to lower disease risk.
But the assumption that saturated fat—or even total fat for that matter—is the chief cause of these diseases is flawed. I have been concerned about this issue for a long time especially when comparing the concepts of wholism with reductionism.[12] [13] [14] One of my more extensive experiences began with my critique of the book, A New Atkins For A New You by Eric Westman, which was published as a comment on the Amazon page for this book (March 18, 2010). It drew 10,000 comments until it was stopped after about three years. That discussion evoked far more ridicule than reason and exposed an unusual hostility by low carb followers. They often think that an argument for a plant-based diet is evidence of religious fanaticism than it is an argument for human health. But that discussion also exposed an irrationality that infuses both sides of this debate (better characterized as a shouting match).
Too many plant-based advocates have depended on the claim or inference that saturated fat (and total fat and cholesterol) is the primary cause of cancer, cardiovascular disease and other degenerative diseases. This is a mistake, both because there is little or no evidence that saturated fat specifically causes these diseases—that is, I agree with the critics of the WFPB diet. Relying on this hypothesis that saturated fat and other lipids cause these diseases is an unfortunate proposition because when this mistake is discovered, as in the recent reports, it gives the appearance that the entire base of supporting evidence for the WFPB diet is questionable.
Saturated fats have long been associated with higher rates of these diseases but this does not mean specific causation. Instead, it means an association of saturated fats with diets of animal origin, especially with animal protein, with which it is closely correlated (r=0.94), as discussed in a recent paper I prepared for the peer-reviewed journal, Nutrition and Cancer.[15] This perspective makes the evidence supporting the WFPB diet even more persuasive. It also offers a much more rational understanding of the reported associations of a variety of nutrients with disease risk. Nutrients typically found in animal-based foods are positively associated with cardiovascular, cancer and related diseases while nutrients typically found in plant-based foods are inversely associated.
This interpretation, by comparing disease risks of animal- and plant-based foods, offers the opportunity to investigate multiple factors in a rational way. It also helps to explain the confusing findings of the well-known Nurses’ Health Study (see pp 270-275 of The China Study[14] ), the Women’s Health Initiative, the recent Mediterranean diet study in Spain[16] and virtually every other study during the past 50 years of subjects using the typical Western diet. The range of dietary experience in these studies is seriously limited. Consumption of whole/intact plant-based foods is consistently low while consumption of animal-based foods and fabricated foods (high in fat, salt and refined carbohydrates) is consistently high. This means most people are using diets high in fat and protein but low in antioxidants and complex carbohydrates, a stacked deck that can only promote disease. None of these studies includes people using a WFPB diet, which is truly low in added fat and added refined carbohydrates (thus eliminating vegan and vegetarian subjects). It’s analogous to comparing trivial health effects of 3-pack per day smokers with 4-pack per day smokers.
Studies on low carb diets are misguided because 1) they are being compared with ‘low fat’ diets that are NOT LOW IN FAT, 2) they often fail to distinguish the difference between the health effects of refined carbohydrates versus natural, complex carbohydrates found in whole foods and 3) they attribute effects to an irrelevant nutrient (i.e., saturated fat) and 4) they compare groups of people uniformly using only very small amounts of those foods that are primarily responsible for disease control and health promotion. The investigators often reveal their bias against the WFPB diet by describing it in the most pejorative language possible, including the likelihood that it is being advocated by vegan activists, for ideological reasons.
Rest assured, we will see yet another one of these failed studies in a year or so. The findings will surely be published in prestigious science journals like JAMA or New England Journal of Medicine that heavily advertise drugs then published by media like the New York Times that have a large, oftentimes influential audience. It is time to take off the gloves and tell it like it is. People are paying huge prices, both financially and in their lives permanently damaged or lost.
I can only wonder whether it will ever be possible to make a major adjustment in our health care system when we must rely on so much flawed science. It’s almost too late—and this is the optimistic view! I also wonder (for one second at the most) why it is so hard to promote better health. We all know the answer for this difficulty and it is measured in money.
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