“It is the position of the Academy of Nutrition and Dietetics [formerly the American Dietetic Association] that vegetarian diets can provide health benefits in the prevention and treatment of certain health conditions, including atherosclerosis, type 2 diabetes, hypertension, and obesity. Well-designed vegetarian diets, that may include fortified foods or supplements, meet current nutrient recommendations and are appropriate for all stages of the life cycle, including pregnancy, lactation, infancy, childhood, and adolescence. Vegetarians must use special care to ensure adequate intake of vitamin B-12.
Vegetarian diets are primarily plant-based, comprised of grains, legumes, nuts, seeds, vegetables, and fruit; do not include flesh foods (beef, pork, poultry and fowl, wild game, and fish); and may or may not include some animal products, such as dairy (milk and milk products), eggs, and processed foods that contain casein or whey.
Although vegetarians may have a higher deficiency risk for some nutrients (eg, vitamin B-12) compared to nonvegetarians, nutritional deficiencies are not the main causes of mortality or morbidity in Western societies.
Vegetarian diets are associated with a lower risk of ischemic heart disease, hypertension, type 2 diabetes, obesity, and some types of cancer; low-fat vegetarian diets, in combination with other healthy lifestyle factors, have been shown to be effective in the treatment of these diseases. Vegetarians have lower low-density lipoprotein, better serum glucose control, and lower oxidative stress. Low intake of foods containing saturated fat and cholesterol, and high intake of vegetables, fruits, whole grains, legumes, nuts and seeds, and soy products that are rich in fiber and phytochemicals are components of a vegetarian diet that contribute to reduction of chronic disease.”
Cullum-Dugan D, Pawlak R. “Position of the academy of nutrition and dietetics: vegetarian diets.” J Acad Nutr Diet. 2015 May;115(5):801-10.