The American Dietetic Association and Dietitians of Canada have stated that at all stages of life, a properly planned vegetarian diet is "healthful, nutritionally adequate, and provides health benefits in the prevention and treatment of certain diseases". Large-scale studies have shown that mortality from ischaemic heart disease was 30% lower among vegetarian men and 20% lower among vegetarian women than in non-vegetarians. Necessary nutrients, proteins, and amino acids for the body's sustenance can be found in vegetables, grains, nuts, soymilk, eggs and dairy. Vegetarian diets offer lower levels of saturated fat, cholesterol and animal protein, and higher levels of carbohydrates, fibre, magnesium, potassium, folate, and antioxidants such as vitamins C and E and phytochemicals.
Vegetarians tend to have lower body mass index, lower levels of cholesterol, lower blood pressure, and less incidence of heart disease, hypertension, type 2 diabetes, renal disease, osteoporosis, dementias such as Alzheimer’s disease and other disorders. Non-lean red meat, in particular, has been found to be directly associated with increased risk of cancers of the esophagus, liver, colon, and the lungs. Other studies have shown no significant differences between vegetarians and non-vegetarians in mortality from cerebrovascular disease, stomach cancer, colorectal cancer, breast cancer, or prostate cancer, although the sample of vegetarians was small and included ex-smokers who had switched their diet within the last five years. A 2010 study compared a group of vegetarian and meat-eating Seventh Day Adventists in which vegetarians scored lower on depression tests and had better mood profiles.