Many people become vegetarians because they believe, in error, that vegetarianism is uniquely conducive to good health. The findings of several large epidemiologic studies indeed suggest that the death and chronic-disease rates of vegetarians primarily vegetarians who consume dairy products or both dairy products and eggs are lower than those of meat eaters. But this does not mean that maintaining or improving health requires abstention from eating meat.
Some vegetarian diets provide less fat, less saturated fat, and fewer calories than typical nonvegetarian diets and have a higher content of fruits, vegetables, and whole-grain products. They thus conform more closely to official dietary guidelines. Eliminating meat from the diet can facilitate decreasing saturated-fat intake and increasing vegetable consumption. But by no means does eliminating meat ensure that one will consume less saturated fat and more plant foods: One might, for example, replace the meat with ice cream. In any case, one can lower one's risk of chronic diseases without abstention from eating meat by limiting intake of high-fat foods; choosing lean red meat, skinless poultry, and low-fat or nonfat dairy products; and eating plenty of grains, fruits, and vegetables.
The health of vegetarians may be better than that of nonvegetarians partly because of nondietary factors: Many vegetarians are health-conscious. They exercise regularly, maintain a desirable body weight, and abstain from smoking. Although most epidemiologists have attempted to take such factors into account in their analyses, it is possible that they did not adequately control their studies for nondietary effects.
People who are vegetarians by choice may differ from the general population in other ways relevant to health. For example, in Western countries most vegetarians are more affluent than nonvegetarians and thus have better living conditions and more access to medical care.
An authoritative review of vegetarianism and chronic diseases classified the evidence for various alleged health benefits of vegetarianism:
* The evidence is "strong" that vegetarians have (a) a lower risk of becoming alcoholic, constipated, or obese and (b) a lower risk of developing lung cancer.
* The evidence is "good" that vegetarians have a lower risk of developing adult-onset diabetes mellitus, coronary artery disease, hypertension, and gallstones.
* The evidence is "fair to poor" that vegetarianism decreases risk of breast cancer, colon cancer, diverticular disease, kidney-stone formation, osteoporosis, and tooth decay.
For some of the diseases mentioned above, the practice of vegetarianism itself probably is the main protective factor. For example, the low incidence of constipation among vegetarians is almost certainly due to their high intakes of fiber-rich foods. For other conditions, nondietary factors may be more important than diet. For example, the low incidence of lung cancer among vegetarians is attributable primarily to their extremely low rate of cigarette smoking. Diet is but one of many risk factors for most chronic diseases.
The above article is an edited excerpt from the new ACSH booklet Vegetarianism.
(From Priorities, Vol. 9, No. 3)