Vegetarian diets are based on cereals, whole grains, pulses, nuts, vegetables and fruits. Lacto-ovo-vegetarians do not consume any meat, poultry or fish but include eggs and dairy products in their diets. Vegans do not consume any food obtained from animals. Other vegetarian diets include fruitarians and macrobiotic diets that are more restricted. Reference to vegetarian diets usually implies lacto-ovo-vegetarians. A number of reasons can be attributed to preference for a vegetarian diet such as religious belief, economic status, personal health issues, environmental and ecological concerns. Vegetarian diets are typically higher in fiber, vitamin C and folate while lower in saturated fat and cholesterol. As can be expected a number of health benefits are attributed to vegetarian diet. Population studies have shown an inverse relation between vegetarian diet practices and incidence of cancer, cardiovascular disease and total mortality1. A number of epidemiological studies have demonstrated the low incidence of obesity, hypertension (high blood pressure) heart diseases, diabetes, cancer etc in vegetarians as compared to meat eaters. People who consume fish and other sea food also demonstrate some advantages of vegetarian diets. 2A 24% decrease in incidence of Ischemic heart disease (IHD) was found among vegetarians as compared to non- vegetarians. Plant foods, which are a good source of fiber, lower cholesterol levels, both low density lipoprotein (LDL) and total cholesterol levels. Lower rates of colon, prostate cancer and breast cancer are also observed in vegetarians. Phytochemicals are excellent anti-oxidants which act by metabolizing carcinogens in the body and lowering the incidence of cancer. Some other phytochemicals such as lignin and phytoestrogens in soy lower the incidence of hormone dependant cancers, such as prostate and breast cancer. This can explain the lower incidence of breast cancer in Asian women who consume soy rich food. Phytochemicals can also block the initial damage to DNA which is associated with various chronic diseases including cancer. No differences in mortality from cancers can be attributed to vegetarian diets, though the mortality rate in people (specially <55 years) due to heart diseases was significantly lower in vegetarians3. If a vegetarian does not include vegetable proteins (soy, tofu, etc.) and does not carefully plan meals to ensure consumption of all essential nutrients, serious deficiencies may occur. Vegetarians (vegans) have difficulty consuming enough of the following nutrients Vitamin B-12, Vitamin D, Calcium, Iron and Zinc. Deficiency of Vitamin D, which is essential for absorption of Calcium, can cause osteoporosis. Another issue associated with a vegetarian diet is necessity of greater amount of food consumption that can provide similar amount of protein.
The amount of protein present in a 3oz. portion of beef ranges from 18-26 gm, a similar portion of soy products can only provide somewhere from 8-16 gm of protein. Vegetarianism is usually not recommended for young children because it is extremely difficult for them to consume the nutrients they need in adequate amounts for optimal growth without consuming any animal products. Some concerns have been raised about the nutrient status of vegetarian athletes, but several studies proved that there was neither a beneficial nor a detrimental effect of vegetarian diet on physical performance capacity4. Vegetarian athletes demonstrated a low cholesterol levels as compared to meat eaters. The requirement for a well planned diet with emphasis on adequate amount of nutrients and minerals such as iron; zinc etc for vegetarian athletes has been underscored. One report of the Congress on Vegetarian Nutrition recommends development of a new food pyramid for vegetarians as opposed to modifying the USDA’s food guide pyramid. According to the recommendation5 the major 5 plant based groups (whole grains, nuts, legumes, vegetables and fruits) form the trapezoid-shaped lower portion of pyramid. Optional food groups, which are avoided by some vegetarians (dairy, eggs, sweets, vegetable oils etc) forms the smaller, separate triangle-shaped portion of the pyramid.
1. Health benefits of a vegetarian diet; Rajaram S., Sabate J. Nutrition, Volume 16, Number 7, July 2000, pp. 531-533(3) 2. Health benefits of a vegetarian diet; Key, T.J.; Davey, G.K.; Appleby. P.N. Proceedings of the Nutrition Society Volume, 58, 1999, pp. 271-5 3. Associations between diet and cancer, IHD and all-cause mortality, Fraser GE, Am. J. Cl. Nutrition; 1999, (suppl) 523S. 4. Physical fitness and a vegetarian diet: is there a relation, Nieman DC; Am. J. Cl. Nutrition; 1999, (suppl) 570S. 5. Vegetarian food pyramid: a conceptual framework, Haddad EH, Sabate J, Whitten CG; Am. J. Cl. Nutrition; 1999, (suppl) 615S.