The authors’ Rebuttal
...to the Dairy Farmers of Canada Response
to Becoming Vegetarian
1996

Parts: 1 | 2 | 3 | 4 | 5 | 6 | 7 | 8
(Part 1)

In May of 1994 Macmillan Canada published Becoming Vegetarian... the complete guide to adopting a healthy vegetarian diet. This book was co-authored by three registered dietitians, Vesanto Melina, Brenda Davis and Victoria Harrison.

As the authors of this book, we were intensely aware of the need for an up-to-date, accurate and reliable resource on vegetarian nutrition. Our primary goal was to help support people in their efforts to achieve excellent health on a plant-based diet. The response to the book was overwhelming. In less than a year, Becoming Vegetarian was a national best-seller. During the next 2 years, the book was updated and released in the U.S. as well as being translated into French and Portuguese.

Both professional and lay reviews of the book have been outstanding, including those from the Canadian Dietetic Association, the American Dietetic Association and the British Columbia Medical Association. The only negative response to date (of which we are aware) came not in the form of a review, but rather as a paid advertisement from the Dairy Bureau of Canada. In the Spring 1996 issue of the Canadian Dietetic Association Journal, a Dairy Bureau of Canada advertisement (Between Dietitians by Helen Bishop MacDonald -- direction of nutrition for the Dairy Bureau) criticized Becoming Vegetarian and made available a 45-page response to the chapter "Without Dairy", free of charge for anyone who requested a copy by calling their toll-free number (Dairy Farmers of Canada Response to Becoming Vegetarian -- Chapter: Without Dairy).

The response offered to our "Without Dairy" chapter overlooked one significant part of the document -- the acknowledgments. The experts to which the Dairy Bureau nutritionists refer in an effort to prove that our work was inaccurate and unscientific were, on more than one occasion, the same experts who reviewed our manuscript and provided the information and guidance for our book. We saw no reference to their input on the Dairy Bureau document.

People reading the Dairy Bureau critique without Becoming Vegetarian on hand for verification, might incorrectly assume that our critics were accurately reflecting our position. The Dairy Bureau response lacked both logic and accuracy, with consistent use of materials taken out of context, serious distortions of our words and blatant disregard for the moral and ethical view points of vegetarians.

Our position on dairy foods is very clear:

"Many North Americans and Europeans rely on milk and its products as major sources of calcium, vitamin D and riboflavin. With the North American style of eating, it can be a challenge to get these nutrients without milk. But this doesn't make cow's milk an essential food" (from "Without Dairy", pages 71-72 in Becoming Vegetarian).

In Becoming Vegetarian, we choose to write a chapter which addresses the nutritional concerns of people who use little or not dairy. Our decision to do this was based on our interaction with other vegetarians and vegetarian organizations. The need for practical information for those who choose to minimize their intake of dairy products was expressed time and time again -- we felt that it would be a serious oversight to ignore this issue in a book on vegetarian nutrition.

The remainder of this rebuttal focuses on key criticisms made in the Dairy Farmers of Canada Response to Becoming Vegetarian (page number and quote from the response appear in bold), followed by and our rebuttal to these criticisms.

Page 1

1. "...the book's claims lack a firm scientific basis"

The resources used in writing Becoming Vegetarian included hundreds of scientific articles from peer reviewed medical and dietetic journals, the World Health Organization's (WHO) technical report #797, Diet, Nutrition and the Prevention of Chronic Disease (1990), Health Canada's Nutrition Recommendations for Canadians (1990), the U.S. Surgeon General's Report (1989) and the National Research Council's Diet and Health, Implications for Reducing Chronic Disease (1989). Each chapter was peer reviewed, and the technical chapters were also reviewed by leading experts in the field -- university professors and associate professors from across the U.S. and Canada. The chapter in question -- Without Dairy -- was reviewed by Dr. Susan Barr, an associate professor of nutrition at the University of British Columbia and portions of the chapter were also reviewed by Dr. Connie Weaver of Purdue University. The section on vitamin D was reviewed by Dr. T.C. Chen, a researcher from Dr. Michael Holick's lab. Numerous professional colleagues also reviewed this chapter.

2. "It also contains a number of errors and false assumptions and the practical aspects of its implementation have not been thought through sufficiently to warrant the recommendations it makes for the general public."

While the nutritionists at the Dairy Bureau of Canada charge us with making errors and false assumptions, leading nutrition experts and scientific researchers, professional colleagues from numerous hospitals, public health nutritionists, private practice dietitians and dietitians representing Dial-a-Dietitian in B.C. not only reviewed the book, but provided resources and assistance to ensure accuracy of the information provided. Every professional organization that has reviewed Becoming Vegetarian to date has given it most favorable recommendations. The following are quotes from these reviews:

With reference to the recommendations made in Becoming Vegetarian, they were directed towards the near-vegetarian, vegetarian and vegan population, rather than to the general public as our critics charge. Our goal in writing this resource was to provide these people with the information necessary to achieve excellent health.

3. "To play a central role in PREVENTION (a theme central to the book's premise), dietary factors must be PROVEN to PREVENT. No study published to date has demonstrated that changing diet prevents coronary artery disease or cancer".

This argument could also be used against Health Canada's Nutrition Recommendations, The Surgeon General's Report on Nutrition and Health (U.S. Department of Health and Human Services), the National Research Council's Diet and Health: Implications for Reducing Chronic Disease and the World Health Organization's Diet, Nutrition and the Prevention of Chronic Diseases. All of these documents are based on a thorough review of the scientific literature, and all agree that we can reduce the incidence of chronic disease by dietary changes, namely eating more grains, vegetables and other plant foods and less fat, particularly saturated fat. The whole concept of disease risk reduction is also referred to consistently as "prevention" throughout the literature.

The WHO states in Diet, Nutrition and the Prevention of Chronic Diseases:

"Medical and scientific research has established clear links between dietary factors and the risk of developing coronary artery disease, hypertension, stroke, several cancers, osteoporosis, diabetes and other chronic diseases. This knowledge is now sufficiently strong to enable governments to assess national eating patterns, identify risks, and then protect their populations through policies that make healthy choices the easy choices."

Health Canada, in Nutrition Recommendations for Canadians, states:

" The Nutrition Recommendations for Canadians are a product of a review of the literature on nutrient requirements and on the various relationships linking nutrition and disease. They are intended to provide guidance in the selection of a dietary pattern that will supply recommended amounts of all essential nutrients, while reducing the risk of chronic diseases."

The U.S. National Research Council in Diet and Health, Implications for Reducing Chronic Disease Risk, states:

"A large and convincing body of evidence from studies in humans and laboratory animals shows that diets low in saturated fatty acids and cholesterol are associated with low risks and rates of atherosclerotic cardiovascular disease. High-fat diets are also linked to a high incidence of some types of cancer and, probably obesity. Thus reducing total fat and saturated fatty acid intake is likely to lower the rates of these chronic diseases."

It is important to note the central theme of the book is achieving adequate nutrition on a vegetarian or vegan diet, not disease prevention. While Chapter two addresses the issues of disease prevention and the nutritional adequacy of vegetarian and vegan diets, this is not the central theme of the book.

4. "If we focus on the SFA-blood cholesterol-CVD links, the analysis of Ramsay et al. clearly reveals that lowering blood cholesterol by current dietary recommendations is rarely as effective as claimed."

We agree that current dietary recommendations are relatively ineffective at lowering blood cholesterol, and we make several statements to that affect in Becoming Vegetarian. Indeed, current recommendations (<30% of calories from fat) result in a cholesterol reduction of about 5-10% at most (recall that reducing plasma cholesterol by 1% results in a decrease in coronary artery disease of at least 2%).1 However, more aggressive diet therapy can result in reversal of coronary artery disease and significant reductions in total and LDL-cholesterol of

30% or more. ^2,3

1. Health and Welfare Canada. Nutrition Recommendations: The Report of the Scientific Review Committee. Ottawa: Supply and Services Canada. 1990.

2. Ornish et al. Can Lifestyle changes reverse coronary heat disease?: The Lifestyle Heart Trial. Lancet. Vol. 336, No. 8708, pages 129-133; 1990.

3. Gould et al. Changes in myocardial perfusion abnormalities by positron emission tomography after long-term, intense risk factor modification. JAMA. Vol. 274, No. 11, pages 894-901; 1995.

5. "Looking at cancer, we see evidence in the research literature that diets rich in polyunsaturates enhance tumor growth and that the fat of ruminant animals contains a substance (conjugated linoleic acid) that is anticarcinogenic. Vegan philosophy would have people consuming more of the former and none or less of the later."

It would appear from this statement that our critics are suggesting that people should consume fewer plant foods and more ruminant fat so that they might increase their intake of conjugated linoleic acid (CLA) and reduce their intake of other polyunsaturated fats. The advice to consume fewer plant foods and more ruminant fat is contrary to the recommendations of every government nutrition body of which we are aware, in addition to every legitimate organization aimed at reducing the risk of chronic disease (i.e. Canadian Cancer Society, Heart and Stroke Foundation, etc.)

Here's what the World Health Organization has to say about the link between diet and cancer:

"Diets high in plant foods, especially green and yellow vegetables and citrus fruits, are associated with a lower occurrence of cancers of the lung, colon, oesophagus, and stomach. Although the mechanisms underlying these effects are not fully understood, such diets are usually low in saturated fat and high in starches and fibre and several vitamins and minerals, including beta-carotene and vitamin A....The experimental data, however, also point to an adverse effect of very high intakes of polyunsaturated fats, at levels that are considerably above current intakes in human populations."1

Dr. Walter Willet and his colleagues in the Department of Nutrition at Harvard Medical School have done extensive, long term research on the links between diet and cancer. In September of 1996 they summarized their findings as follows:

"...we have a good idea of what people should eat if they want to improve their odds of avoiding cancer. Their diet should be high in vegetables, fruits and legumes (such as peas and beans) and low in red meat, saturated fat, salt and sugar. Carbohydrates should be consumed as whole grains -- whole-wheat bread and brown rice as opposed to white bread and rice, for example. Added fats should come mainly from plants and should be unhydrogenated; olive oil, especially, appears potentially beneficial."2

The potential danger from excessive amounts of polyunsaturated fats is thought to be due to the oxidation of these unstable molecules - particularly when antioxidants are in low supply. Fortunately, vegetables and fruits come packaged with antioxidants which can reduce lipid peroxidation. Research suggests that the level of polyunsaturated fat must be considerably higher than is seen in human populations, thus the overall impact of these fats is likely to be very low. On the other hand, the WHO points out that diets high in saturated fat and low in plant foods and fibre are most highly associated with diet-related cancers.

It is interesting to note that the anticarcinogenic substances referred to in the Dairy response are actually a group of positional and geometric isomers of linoleic acid (an omega-6 fatty acid). While the two double bonds on linoleic acid are in the 9 and 12 positions, in CLA, the double bonds are at the 9 and 11, and 10 and 12 positions. While there may be some evidence to suggest that this group of polyunsaturated fatty acids may have some anticarcinogenic potential, it does not make foods which contain this fat anticarcinogenic foods, nor does it negate all of the potentially damaging effects of the excessive saturated fat they might contain.

If we compare the anticarcinogenic substances in the fat of ruminant animals vs the anticarcinogenic substances found in plant foods, there would be no contest. Plant foods are not only generally low in fat and high in fibre but they are loaded with phytochemicals that are potent anticarcinogens. Many commonly consumed plant foods contain literally hundreds of potent phytochemicals. By contrast, the fat of ruminant animals is over 50% saturated, is fibre-free and totally void of the protective phytochemicals found in plant foods. To suggest that people should consume more ruminant animal fat and less plant foods to reduce cancer risk shows a complete disregard for the research conducted on this vitally important disease over the past 2-3 decades.

Finally, if their logic was correct, vegans and lacto-ovo vegetarians would experience a greater incidence of cancer than omnivores. There are many studies to show that vegetarians and vegan experience significantly less cancer as compared to omnivores. 3-5

1. WHO Study Group on diet, Nutrition and the Prevention of Non-Communicable Diseases. Diet, Nutrition and the Prevention of Chronic Disease. Geneva, Switzerland: Technical Report Series No. 797. World Health Organization, 1990.

2. Willet, W., Colditz, G. and Mueller, N. Strategies for minimizing cancer risk. Scientific American. September, 1996.

3. Thorogood, M., Mann, J., Appleby, P. and Mcpherson, K. Risk of death from cancer and ischaemic heart disease in meat and non-meat eaters. Br Med.J. Vol. 308:1667-1671, 1994.

4. Mills, P. Cancer among Seventh-day Adventists. Am.J.Clin.Nutr. 91:836-840, 1994.

5. Phillips, R. and Snowden, D.A. Association of meat and coffee use with cancers of the large bowel, breast, and prostate among Seventh-day Adventists. Preliminary results. Cancer Research. 43(suppl):2403s-2408s, 1983.

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