|Enewsletter • April 18, 2002|
Report on the Fourth International Congress on Vegetarian Nutrition
—Jack Norris, R.D.
From April 8 to 11, leading researchers and others interested in vegetarian nutrition convened at Loma Linda University for the Fourth International Congress on Vegetarian Nutrition, a conference presenting the latest information on matters related to vegetarian diets.
These congresses take place only once every five years. There were about 400 people in attendance, many of whom do research on vegetarian diets. Health professionals who promote vegetarian diets were also present, as well as some doctors and dietitians attending for continuing education credits and/or because they are interested in the research.
The conference was organized by the two separate departments of nutrition at Loma Linda University, which is a Seventh-day Adventist (SDA) university. The SDA church promotes a vegetarian diet among its members and has long been at the forefront of vegetarian nutrition research. In fact, the only long-term studies of vegetarians in the United States have been conducted on members of the SDA church.
Funding for the conference was provided by the International Tree Nut Council, Loma Linda University Medical Center, Wellsource, Inc., Kellogg's/Worthington Foods, Lifestyle Center of America, Health Ministries Department of the Seventh-day Adventist Church, and Vibrant Life Foods.
I was somewhat disappointed to see that many of the popular American vegan advocates who speak and write on health issues were not in attendance. It would be nice to get both the researchers and the advocates together so that we can all get on the same page, and thus reduce some of the discrepancies that we often present to the public. Perhaps this could be a goal for the next congress.
Below are what I considered to be the highlights of the conference.
There were a number of presentations about the roles of phytochemicals and their effects in preventing various chronic diseases. Phytochemicals are plant chemicals that are not essential for life but appear to have many benefits. Many are antioxidants believed to protect against heart disease and cancer. Not much is yet known about most of them.
Dr. Timothy Key presented some interesting news regarding the mortality rates of British vegetarians. Dr. Key is from the Cancer Epidemiology Unit at the Radcliffe Infirmary in Oxford, England. (A bit more about Dr. Key is here) He presented findings from 3 large studies in the UK. Two of those studies, the Health Food Shoppers Study and the Oxford Vegetarian Study, have had findings reported earlier. However, the findings for the third study, the European Prospective Investigation into Cancer (EPIC)-Oxford, have not been reported before and are considered preliminary. An excerpt from Dr. Key's abstract summarizes the findings:
Dr. Key was asked why vegetarians in Britain do not show lower mortality rates than their meat-eating counterparts, while SDA vegetarians live longer than meat-eating SDAs. He theorized that in the UK, vegetarianism is not the norm and vegetarians are therefore nonconformists, which could cause stress. In contrast, SDAs are encouraged to be vegetarians and have a strong support group.
To date, not enough vegans have been studied to produce statistically significant results regarding their mortality. I was optimistic that our knowledge might improve as more results from the EPIC-Oxford study come in, as it includes 2,000 vegans. However, Dr. Key told me that this would still be an insufficient number of vegans to create as much statistical power as is needed to provide much more insight. He said that we know vegans don't have unusually high death rates, but we don't know much more than that, and we probably won't for many years.
Dr. Synnove Knutsen (Loma Linda University) presented findings from the Adventist Health Study looking at hip fractures in vegetarians compared to meat-eaters. Unfortunately, they found that the more animal foods someone ate, the less likely they were to have a hip fracture. I thought this was the most disappointing information presented at the conference. It seems to provide further evidence that vegans need to make a strong effort to meet the RDA for calcium, vitamin D, and protein (please see my article Staying a Healthy Vegan for more information).
Dr. Frank Hu (School of Public Health at Harvard University) spoke on plant foods and cardiovascular disease (CVD). He expressed the view that the omega-6/omega-3 ratio was not significant in CVD, and that the emphasis should not be on decreasing omega-6 oils, but on increasing omega-3 oils (via flaxseed or fish oils).* This could be seen as good news because, if true, vegans might not have to worry as much about their typically high intakes of omega-6. However, CVD is only one disease affected by omega-3 status, and other diseases are likely to be more sensitive to the omega-6/omega-3 ratio. At this time, the bulk of the evidence favors that vegans limit their intakes of omega-6 oils by following these recommendations.
*Thanks to Tom Billings for allowing me to use his notes from this talk.
Dr. David DeRose (Medical Director of the Lifestyle Center of America, Sulphur, OK) made a presentation underlining the need for vegans to supplement with vitamin B12 in order to keep their homocysteine levels healthy. Elevated homocysteine is a risk factor for CVD, Alzheimer's disease, and neural tube birth defects, among other diseases. Since vegans typically get ample amounts of folate, which is also necessary to keep homocysteine levels healthy, a B12-supplemented vegan diet is a great choice for lowering homocysteine. Dr. DeRose pointed out that iceberg lettuce contains large amounts of choline, a molecule thought to have beneficial effects. (Finally, a positive quality of iceberg lettuce!)
Jacqueline Chan (School of Public Health, Loma Linda University) presented findings from her research looking at fluid intake and risk of fatal heart attack and stroke. She found that people consuming five glasses of water per day had a 37-54% lower risk for dying of heart attack or stroke than those consuming one glass per day. Fluids other than water were not found to be protective.
Dr. Zoue Lloyd-Wright (Nutrition Food and Health Research Center, King's College, London) presented findings from the Oxford section of the EPIC-Oxford study about the omega-3 levels of vegans and omnivores. They found that omnivores had higher levels of all omega-3 fatty acids, including linolenic acid, EPA, and DHA. She concluded that "Whether these differences in plasma [omega]-3 fatty acid concentrations are of pathophysiological significance is yet to be determined." The results of this study support the need for vegans to get a daily source of omega-3s. See Staying a Healthy Vegan for more information.
Dr. Janet Hunt (University of North Dakota) presented her research on trace minerals in a vegetarian diet. The abstract for her talk in the conference program reads:
I find the above abstract to be a pretty fair assessment of the situation. However, in her actual presentation, Dr. Hunt emphasized the iron absorption-inhibiting factors in vegetarian diets, while neglecting the role of vitamin C in enhancing iron absorption. Had I not known better, I would have come away from her talk amazed that any vegetarian is able to avoid iron-deficiency anemia.
Although studies of vegetarians have not shown iron stores to be related to intake of vitamin C in general, there have been numerous studies showing that adding vitamin C to meals significantly increases iron absorption. Additionally, in a study of vegetarian Indian children with iron-deficiency anemia, a 100-mg tablet of vitamin C at both lunch and dinner for 60 days caused a drastic improvement in their anemia, with most making a full recovery. (Source: Seshadri S, Shah A, Bhade S. Haematologic response of anaemic preschool children to ascorbic acid supplementation. Hum Nutr Appl Nutr. 1985 Apr;39(2):151-4.)
Dr. Walter Willett of the Harvard University School of Public Health, one of the world's foremost nutritional epidemiologists, was in attendance. He discussed the importance that studies on SDAs have had on our understanding of nutrition.
In the morning, presentations about the environmental sustainability of animal- vs. plant-based diets were made. New information was presented by two researchers:
Ingrid Hoffman (Institute of Nutritional Economics and Sociology, Karlsruhe, Germany) presented an analysis of three diets for greenhouse gas production:
The lacto-ovo vegetarian diet resulted in the least environmental harm as determined by carbon dioxide and sulphur dioxide production.
In contrast, Hal Marlow (Loma Linda University) presented a paper measuring the pesticide use involved in different diets in the state of California. He found that the production of a vegetarian diet may be associated with more pesticides. He pointed out that cantaloupe, which receives an unusually high amount of pesticides, was used as the model for "seasonal fruit." If a different model had been chosen, the outcome might not have been the same. (Note: The pesticides used on the crops fed to animals were taken into account.)
Brenda Davis, RD (coauthor of Becoming Vegan) discussed how to achieve optimal essential fatty acid status for vegetarians. Her recommendations were similar to those in Staying a Healthy Vegan (which Brenda Davis and others have reviewed).
Timothy Key presented results of a study showing that vegans had lower circulating levels of insulin growth factor-1 (IGF-1), which is thought to be a cause of some cancers.
Special Event – Food's Broader Context: Ethics, Ecology & Spirituality
I thought the highlight of the conference was Timothy Key's discussion about animals. He said he had never before spoken publicly on the subject of animal rights, yet he gave an eloquent presentation as to why people should avoid animal products. The main theme was (and I'm paraphrasing) that anyone who knows animals knows they are individuals; and because they are individuals with personalities, their lives should be respected. He then detailed some conditions farmed animals must endure.
Dr. Mark Messina (Department of Nutrition at Loma Linda University) presented on soy. He said that for reducing heart disease, osteoporosis, and some cancers, people should eat 2-3 servings of soyfoods a day. This translates to about 10-25 g of soy protein and 30-100 mg of isoflavones (a group of molecules found in soy that have a variety of unusual properties). Messina pointed out that .5% (1 in 200) of people are allergic to soy.
Dr. Thomas Badger (Professor of Pediatrics, University of Arkansas for Medical Sciences) discussed soy intake among children. He said that the health of children who are given soy formula as infants does not differ from those who receive breastmilk. He made the point that many soy researchers' children are on soy, which wouldn't be the case if there were evidence of danger. Dr. Ken Setchell added that much of the anti-soy information that can be found on the Internet originates as one or two sentences from an animal study (i.e., taken far out of the context of the entire body of scientific findings on soy).
Dr. Joan Sabaté (Loma Linda University) made a presentation called "Nuts and Body Weight: A Negative Interaction?" He started off the presentation saying that we don't know for sure how nuts affect body weight. However, he presented some fairly impressive research that indicated nuts can actually decrease body weight. For example, in SDAs, higher nut consumption is associated with lower body weight. A study in Spain found no difference between those consuming more nuts and those consuming less. One study showed that nuts can increase fat excretion, whether raw, roasted, or as nut butters. This could possibly explain why nuts do not seem to contribute to weight gain. This is good news because nuts are associated with lower rates of heart disease in several epidemiological studies.