Am J Clin Nutr. 1999 Sep; 70(3 Suppl): 434S-438S.

Convergence of philosophy and science: the third international congress on vegetarian nutrition.

Willett WC.

Department of Nutrition, Harvard School of Public Health, Boston, MA 02115, USA.

Populations of vegetarians living in affluent countries appear to enjoy unusually good health, characterized by low rates of cancer, cardiovascular disease, and total mortality. These important observations have fueled much research and have raised 3 general questions about vegetarians in relation to nonvegetarians: Are these observations the result of better nondietary lifestyle factors, such as lower prevalences of smoking and higher levels of physical activity?; Are they the result of lower intakes of harmful dietary components, in particular meat?; and Are they the result of higher intakes of beneficial dietary components that tend to replace meat in the diet? Current evidence suggests that the answer to all 3 questions is "Yes." Low smoking rates contribute importantly to the low rates of cardiovascular disease and many cancers, probably including colon cancer, in Seventh-day Adventists and other vegetarian populations. Also, avoidance of red meat is likely to account in part for low rates of cardiovascular disease and colon cancer, but this does not appear to be the primary reason for general good health in these populations. Evidence accumulated in the past decade emphasizes the importance of adequate consumption of beneficial dietary factors-rather than just the avoidance of harmful factors-including an abundance of fruit, vegetables, and whole grains and regular consumption of vegetable oils, including those from nuts. Although current knowledge already provides general guidance toward healthy diets, accumulated evidence now strongly indicates that diet has a powerful yet complex effect on health and that further investigation is needed.