The Nutrition of a Natural Foods Diet
August 4, 2011
A Vegetarian Sourcebook was first published in 1983. What revisions would I make to section I of A Vegetarian Sourcebook (AVS) on "Vegetarian Nutrition," if I were to rewrite it today?
In the first place, AVS was written to identify issues about the vegetarian diet and then to assess them. It was not about recipes or practical advice. The basic stance of AVS was that the best diet was a whole-foods, low-fat, vegan diet. "Meat in particular, and animal products in general, have three nutritional disadvantages: they contain too much fat, they contain too much protein, and they contain no fiber at all" (p. 52). My method was to go straight to the sources, which meant reading medical journals, scientific studies, and the like.
In my revision, I would do three things differently: (1) slightly modify my basic stance, (2) completely change my research approach, and (3) evaluate the contemporary anti-vegetarian literature and opinion.
There are several changes to my basic stance which I would make today.
1. Strengthen the recommendations for vegans getting vitamin B-12. It was not until I started hearing of vegans dying from heart disease that I was convinced that as a practical matter this issue was much less controversial than initially appeared during the 1980ís, even though there may be some theoretical issues which are unclear.
2. Distinguish between the different kinds of fats, such as omega-3ís, DHA and EPA, saturated fats, and trans fats; and in that context some nuts and seeds (especially flax, walnuts, etc.) could be helpful.
3. There is a whole category of diseases, such as mad cow disease and avian flu, which fall outside of the category of "traditional" infectious diseases like cholera and smallpox, and chronic degenerative diseases like heart disease and obesity. These were mostly unknown during the 1980ís or were not controversial subjects.
4. Protein is still a slightly controversial topic, with some vegan experts raising concerns that some vegetarians (raw food people? fruitarians?) may not be getting enough protein after all. I would need to investigate this in some more detail.
5. I would be a lot less hesitant about advocating veganism on nutritional grounds.
The basic stance of AVS is the classic low-fat approach typical of Nathan Pritikinís followers. This comes out clearly in the appendix in the third and fourth printings, where I put nuts and seeds in the same category as animal products ó as foods to avoid on health grounds.
Vegetable fats in the American diet are typically just as bad as animal fats, but thatís because they are typically in the form of refined fats (corn oil, safflower oil, and so forth). Nuts and seeds often are quite beneficial (walnuts, pecans, filberts, and flax seed come to mind, and brazil nuts have selenium). Moreover, we need to distinguish between the helpful fats (omega-3 fatty acids, DHA, EPA), saturated fats (which are bad) and the trans-fats (which are downright evil), as well as some middle of the road fats like olive oil.
Personally I am still not enthusiastic about fat consumption, aiming for about 15% of calories as fat. I do eat some nuts and seeds in moderation. Somewhat less frequently I eat foods like tofu; and I use oils and sugars even less frequently than that. I grease my bread pans lightly with olive oil to keep the bread from sticking, and put a small amount of sugar in the flour mix. The only time Iíll eat vegetables cooked in oil, or oily sauces, is on occasions like the monthly vegetarian potluck when Iím eating other peopleís dishes, or the occasional restaurant meal. Thatís pretty much my life with vegetable fat. Dr. McDougall would probably wag his finger, but let me get away with it as long as I am otherwise well behaved.
Researching the Book
Thereís another consideration, and that is that today I wouldnít start by reading journal articles. Iíd read all the vegan nutritionists, dietitians, and doctors that we already have and look at what they have to say. I follow closely both John McDougallís writings on this subject, which I have been impressed with for decades, as well as Michael Gregerís, especially his excellent new web site "nutritionfacts.org". But besides McDougall and Greger, there are people such as T. Colin Campbell, Vesanto Melina, Brenda Davis, Ginny Messina, Neal Barnard, and many others, who are all doctors, nutritionists, or dietitians. I would try to identify points on which they seemed to agree, or not to agree, and only then look at primary sources after I had surveyed the scene.
How totally different this is from the situation in 1980! At that time, for all practical purposes there were no secondary sources by credentialed experts on vegetarian nutrition. In fact a well-known vegetarian dietitian involved with the ADA approached me after my book came out to thank me for the contribution AVS had made to the literature on the subject!
For AVS, I did read Robin Hurís Food Reform: Our Desperate Need, and the books by Nathan Pritikin. But neither of these people were "credentialed" in medicine or nutrition. Moreover, I didnít rely on anything that they said; I tried to track down everything. Everything about vegetarian and vegan diets was controversial. The first real book which I recall on vegan diets by someone who was credentialed was The McDougall Program by John McDougall, which serendipitously came out almost on the same day that AVS did.
Controversies about Vegetarianism
Since the focus of AVS was on issues surrounding a vegetarian diet, I would have to acknowledge that the things which are controversial today are quite different from the things which were controversial in the 1980ís. There are two different kinds of issues ó (1) issues between vegetarians and other vegetarians, and (2) issues between vegetarians and nonvegetarians.
Ironically, the really hot internal issue among vegetarians in the 1980ís ó veganism versus lacto-ovo-vegetarianism ó is today almost completely a non-issue within the vegetarian community. Veganism is completely dominant. At most, a few experts (Ornish, Fuhrman) will tolerate small amounts of animal products in the ideal diet, which could be dairy products and eggs, but no one (as far as I know) is promoting dairy and eggs as something which should be consumed because theyíre healthful. If there is a nutritional advocate of lacto-ovo-vegetarianism, I donít know who it is. This is the single most important result of the whole scientific debate about vegetarianism since 1980.
Today, there are more scientific issues, and of more substance and interest, within the vegetarian community than between vegetarians and nonvegetarians. The most important of these are lingering controversies over protein and fat. But they are over questions of detail, and there is basic agreement on veganism. In short, these controversies might marginally affect what kind of vegan diet you adopt, but not whether you will adopt a vegan or near-vegan diet (on nutritional grounds).
What about "the other side"? What about issues between vegetarians and non-vegetarians? Yes, people do attack vegetarianism and veganism on nutritional grounds, but no one has really summarized the arguments against vegetarianism in a coherent way. In fact, there are very few intellectuals (who are not already vegans or near-vegans) who even understand that there is a problem here. There is a serious intellectual divide here: you either understand the problem, and agree with the vegans on nutritional questions ó or you donít understand the problem.
Opponents of veganism sometimes have quite a bit of money behind them, and have added a lot of hot air, but nothing really substantial from a scientific point of view. I would need to assess some of the "controversial literature" on the other side, such as books like Gary Taubesí Good Calories, Bad Calories, Lierre Keithís The Vegetarian Myth, the innumerable books by the late Robert Atkins, the Weston A. Price Foundation authors, and Michael Pollanís arguments against vegetarianism in The Omnivoreís Dilemma.
Pollanís book is in a separate category. It has quite a bit of positive material, and with this book as well as one of his other books, In Defense of Food, he has considerably broadened the dialogue on diet. On the other hand, his objections to vegetarianism are rather scattered; he really doesn't seem that familiar with the nuts and bolts of the science.
For science, this is a truly dangerous situation. Popular understanding and scientific understanding diverge significantly. The historian Crane Brinton cited "the desertion of the intellectuals" as an important precursor of political revolutions. The same thing may be true of scientific revolutions as well.
There are plenty of people who ignore veganism, as well as some who attack it. But there are few intellectuals today who actively try to defend the idea that the standard American diet is healthy. In fact, snide criticisms of the way Americans eat are very common. Even those who ignore or decry veganism often have their own criticisms of the standard American diet, such as the Weston A. Price Foundation (which argues for organic meats and against refined plant foods) and Michael Pollan, who says that we should eat "mostly plants." We are on the verge of a scientific revolution.
The books by Taubes, (Lierre) Keith, Atkins, Pollan, and others, are much more influential than most vegans give them credit for. The problem here is that it is pretty slow going sorting through the mountains of disinformation, quotations out of context, and the occasional accurate insight, to identify what actually is an "issue." Moreover, there is no single consistent point of view put forward by these writers ó it is a mish-mash of thoughts, and they disagree with each other as well as with us.
Michael Greger did a service to science by publishing Carbophobia, which pretty thoroughly destroyed the Atkins diet. But the Atkins diet, and Atkins-like diets, still has considerable intellectual respectability in many circles. It is by no means dead. Their advocates (front groups or "astroturf" groups for the livestock industry, most likely) are quite active and aggressive in internet forums. Their arguments need to be confronted.
In summary, the basic thrust of AVS (a whole-foods vegan low-fat diet) is still correct, and all the evidence I cited is still valid. A lot of new evidence and new issues have come up since then, but old issues have been resolved and the number of vegan nutritionists, dietitians, and doctors is multiplying by leaps and bounds as well. I certainly would need to bring the evidence I cite up to date. On the other hand, an old study does not become invalid simply by virtue of being old, but only when new information revises or corrects it.
The main opposition to vegan diets on nutritional grounds today comes not from scientifically based anti-vegetarian arguments, but from ignorance, blind adherence to cultural beliefs about foods, and from disinformation spread by industrial agriculture for their own financial gain.