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3rd International Congress on Vegetarian Nutrition - Loma Linda, March 23-26,1997

from EVU News, Issue 2 /1997 - Italiano

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Prof. Dr. Marcel Hebbelinck, 10 Merelaan, 1150 Brussels, Belgium
Tel/Fax: +32 267 38437
The Third International Congress on Vegetarian Nutrition was hosted by Loma Linda University, School of Public Health (Department of Nutrition) and the School of Allied Health Professions (Department of Nutrition and Dietetics). The two previous congresses were held in 1987 (Washington DC) and 1992 (Arlington, VA), and the proceedings of these congresses were published in The American Journal of Clinical Nutrition (Supplementum Volume 48, number 3(S), September 1988; Supplementum Volume 59, number 5(S), May 1994). These scientific reports contain a wealth of information relative to vegetarian dietary practices.

The 1997 Congress, organised in the brand new Wong Kerlee International Conference Center of Loma Linda University, took place from March 24-26, 1997, and attracted more than 600 scholars and students from 28 countries from all over the world. An outstanding three-day programme of lectures, posters, workshops, panel discussions was organised under the competent leadership of Dr. Patricia Johnston and Dr. Joan Sabaté. Additionally, besides the rewarding scientific and educational meetings, a fine social programme was provided. Personally, I had the pleasure to serve on the advisory board, to make a presentation (Growth, Development and Physical Fitness of Flemish Vegetarians) as an invited lecturer and to chair a plenary session on “Health Issues in the Lifestyle of Vegetarians”.

It is difficult, if not impossible, to sum up all the highlights of this conference, because so many papers presented were of high scientific quality. However, we shall attempt to present here some of the most interesting communications.

Dr. Walter Willett (Professor of Epidemiology and Nutrition of Harvard School of Public Health) gave the keynote address entitled “Vegetarian Diets : The Convergence of Philosophy and Science”. Referring to several recent studies Dr. Willett stated that ‘populations of vegetarians living in affluent countries (a.e. Germany, England, USA, Australia) enjoy unusually good health, characterised by low rates of cancer, cardiovascular disease, and total mortality’. Because of possible interferences of other non dietary lifestyle variables, such as low prevalence of smoking and higher levels of physical activity in vegetarians, questions have been posed as to the beneficial influence of a vegetarian diet as the sole factor of better health. After careful analysis of the epidemiological studies on vegetarian populations, Dr. Willett emphasised the importance of adequate consumption of beneficial dietary factors, rather than just the avoidance of harmful factors. This includes that abundant intake of fruits and vegetables, the regular consumption of vegetable oils including those in nuts, and the importance of consuming grains in a minimally refined state”.

With regard to the consumption of nuts, Dr. Joan Sabaté (Chairman of the Nutrition Department of the School of Public Health of Loma Linda University) reported that in the last 5 years the evidence has been accumulated that nut consumption protects against coronary heart disease (CHD) - the leading cause of death in affluent societies. Nuts also constitute an important part of traditional plant-based diets (such as the Mediterranean and Asian diets). Dr. Sabaté reported that in a prospective epidemiological study of approximately 31.000 Californian Adventists the frequency of nut consumption had a substantial and highly significant inverse association with risk of myocardial infarction and death from CHD.

The question of the possible health effects of legumes and soybeans was expertly dealt with by Dr. Mark Messina (nutrition consultant). According to Dr. Messina legumes are an excellent source of dietary fiber and are generally between 20 % and 30 % protein. Because the glycemic index of beans is very low it may be an interesting food source for diabetics. Moreover, legumes offer a variety of potentially beneficial phytochemicals such as saponins and isoflavones (particularly soybeans). According Dr. Messina “recent data suggest isoflavones may promote bone mineralisation and reduce risk of both cardiovascular disease and some forms of cancer”.

In his lecture on cereals and legumes, Dr. Lawrence Kushi (Associate Professor, Division of Epidemiology of the School of Public Health, University of Minnesota) however, is more cautious in his conclusions stating that “the role of legumes in coronary heart disease and some cancers is promising but inconclusive, whereas there is substantial epidemiological evidence that dietary fiber and whole grain intake is associated with decreased risk of coronary heart disease and some cancers”.

Interesting was the information about the role of phytic acid given by Dr. Joanne Slavin (Professor at the Department of Food Science & Nutrition, University of Minnesota). It is known that whole grains are rich source of compounds formerly thought of as antinutrients, for example phytic acid. However, Dr. Slavin said, it has been found that “phytic acid may function as an antioxidant in human foods and therefore be protective, rather than detrimental to human health”.

The present day growing concern about osteoporosis has been also a topic of discussion at this congress. Dr. John Anderson (Professor of Nutrition, University of North Carolina) gave an excellent survey on the world-wide problem of bone health with striking steep increase of the prevalence of hip fractures in newly affluent countries in East-Asia, like Hong Kong and Singapore. “Besides preventive strategies such as physical activity, dietary factors are extremely important and not simply calcium in promoting bone health. New information is emerging about the potential beneficial role of plant molecules to bone health. The phytoestrogens, such as genistein and dadzinn, found in soybeans and their products are now being tested in humans to uncover the significance of their bone preserving role”. Dr. Anderson emphasised the fact that it is not just a question of calcium supplementation or of increasing the intake of dairy products, but much more complex mechanisms in which food molecules from plant sources may play an important role in the prevention strategies of osteoporosis.

Interesting in this connection was the research done by Dr. Connie Weaver (Professor and Head of the Department of Foods and Nutrition, Purdue University) on the calcium bio-availibility from a variety of plant sources as compared to milk. “Generally, plants which contain oxalic acid have poor calcium bio-availibility except for soy-beans, whereas plant sources which are low in both oxalic and phytic acid have better calcium bio-availibility than milk although the amount per serving is lower”. Dr. Weaver drew attention to the fact that for every gram of dietary salt consumed, approximately 26 mg calcium is lost in the urine and for every gram of protein approximately 1 mg additional calcium in the urine is lost. Her conclusion was “that diets can be constructed which are higher in calcium or lower in salt, protein, caffeine, and other constituents which lead to calcium loss”.

Another question which is frequently raised is the assumption that menstrual disturbances are more common among vegetarians. Dr. Susan Barr (Professor of Nutrition, University of British Columbia), after critically reviewing the relevant literature concluded that “the wealth of evidence suggests that vegetarianism per se does not contribute substantially to the development of menstrual disturbances”.

The question of physical performance capacity of vegetarian athletes was reviewed by Dr. David Nieman (Professor at the Department of Health, Leisure & Exercise Sciences, Appalachian State University) and he concluded that “there are no convincing data, that vegetarian athletes suffer impaired nutrient status from the inter-active effect of their heavy exertion and plant food based dietary practices. Although there has been some concern about protein intake for vegetarian athletes, data indicate that all essential and nonessential amino acids can be supplied by plant food sources alone as long as a variety of foods is consumed and the caloric intake is adequate to meet energy needs”. In an ensuing workshop Dr. Nieman presented several examples of vegetarian menus as followed by athletes and physical fitness adepts, showing that a varied and well-planned vegetarian diet is compatible with successful athletic performance.

In a well documented presentation Dr. Winston Craig (Professor of Nutrition, Andrews University, Michigan) focused on the health promoting properties of common herbs, that possess hypolipidemic, antiplatelet, antitumor or immune-stimulating substances that may significantly reduce the risk of cardiovascular disease and cancer. Among other things , Dr. Craig discussed the biochemical activity of the Allium family(e.g. garlic, onion), the Umbelliferae (e.g. celery, parsley, carvi, dill, cilantro), Labiatae (e.g. mint, marjory, thyme, sage, nettles), families as well as flax seed, licorice root, and green tea. Many of these herbs possess very potent antioxidant compounds that may protect LDL cholesterol from oxidation, inhibit lipoxygenase and cyclo-oxygenase enzymes, inhibit lipid peroxidation, and have antiviral or antitumor activity. Moreover, Dr. Craig indicated that the volatile essential oils of commonly used culinary herbs and spices and herbal teas may inhibit mevalonate synthesis (mevalonate = a salt or dissociated form of mevalonic acid, a precursor of squalene, cholesterol, and coenzyme Q) and thereby suppress cholesterol synthesis and tumor growth.

“The idea that dietary factors may influence rheumatoid arthritis (RA) has been part of the folklore of this disease”, said Dr. Jens Kjeldsen-Kragh (Medical Consultant, Department of Immunology, Ullevaal Hospital, Oslo), but scientific support has been sparse. Dr. Kjeldsen-Kragh reported on the outcome of a controlled single blind trial, testing the effect of fasting for 7-10 days followed initially by an adjusted gluten-free vegan diet for 3.5 months. For all clinical trials, the 27 patients who were randomly assigned to fasting and the vegetarian diet improve significantly compared with 26 patients in the control group, who followed their usual omnivorous diet. The beneficial effects as observed by clinical protocols were substantial. The results of this study show that patients with RA can benefit from a fasting period followed by a vegetarian diet, as a valuable adjuvant to the ordinary therapeutic treatment of RA.

Three large epidemiological investigations on vegetarians were presented in which different issues were studied. Dr. Timothey Key (UK) reported on pooled data for 27.808 vegetarians and 48.364 omnivores of five prospective studies, and concluded that “vegetarians have a lower risk of dying from coronary heart disease than non-vegetarians, but there is no evidence from this analysis that a vegetarian diet alters the mortality rates for cancers of the colorectum, breast or prostate”.

Dr. Margaret Thorogood gave information about The Oxford Vegetarian Study, which has a cohort of around 6,000 non-meat eaters and 5,000 meat eaters who have been followed since the early 1980’s. It was found that the consumption of animal fat shows a strong relationship with risk of death from coronary heart disease.

In a third epidemiological study, Dr. Gary Fraser reported on diet and chronic diseases among California Adventists (no. = 34,192) of which food frequency data were collected in 1976 and then followed for 6 years to find all cases of coronary artery disease and cancer, and for 13 years to find all deaths. Dr. Fraser found that “for nearly all endpoints, vegetarians had lower risk than non-vegetarian Adventists. More particularly, frequent consumption of legumes was associated with reduced incidence of pancreatic cancer, and colon cancer (amongst the non-vegetarians); frequent consumption of fruit was associated with lower incidence of lung, pancreatic, and prostate cancer. Consuming nuts 4-5 times a week was associated with a halving of coronary event risk, and a preference for whole grain bread was associated with 30 % lower risk of these events. Frequent consumption of red meats was associated with higher rates of bladder cancer, and in men, fatal coronary events. Frequent consumption of white and red meats was associated with higher incidence of colon cancer (when legume consumption was low)”. Based on the results of this large epidemiological study, Dr. Fraser concluded that the advantages of a vegetarian diet seem to be both due to higher consumption of legumes, fruits, and polyunsaturated fats, as well as the non- (or lower) meat consumption.

The results of our study on Flemish vegetarian children, adolescents and young adults will be summarised in a separate article.

The main papers presented at the Third International Congress on Vegetarian Nutrition are now under review and will be published in full in the American Journal of Clinical Nutrition.

A review of selected poster presentations (a.e. of Dr. Igor Bukowski and coll. on atherogenesis and by Dr. Peter Clarys and the present reporter - MH - on creatine supplementation in vegetarians compared with non vegetarians) will be discussed in a later report.