scholar.google.co.uk/scholar?q=american+dietetic+association+vegan&hl=en&as_sdt=0&as_vis=1&oi=scholart#d=gs_qabs&p=&u=%23p%3DzzWTVLCcsXgJ
Abstract :
It is the position of the American Dietetic Association that appropriately planned vegetarian diets, including total vegetarian or vegan diets, are healthful, nutritionally adequate, and may provide health benefits in the prevention and treatment of certain diseases. Well-planned vegetarian diets are appropriate for individuals during all stages of the life cycle, including pregnancy, lactation, infancy, childhood, and adolescence, and for athletes. A vegetarian diet is defined as one that does not include meat (including fowl) or seafood, or products containing those foods. This article reviews the current data related to key nutrients for vegetarians including protein, n-3 fatty acids, iron, zinc, iodine, calcium, and vitamins D and B-12. A vegetarian diet can meet current recommendations for all of these nutrients. In some cases, supplements or fortified foods can provide useful amounts of important nutrients. An evidence- based review showed that vegetarian diets can be nutritionally adequate in pregnancy and result in positive maternal and infant health outcomes. The results of an evidence-based review showed that a vegetarian diet is associated with a lower risk of death from ischemic heart disease. Vegetarians also appear to have lower low-density lipoprotein cholesterol levels, lower blood pressure, and lower rates of hypertension and type 2 diabetes than nonvegetarians. Furthermore, vegetarians tend to have a lower body mass index and lower overall cancer rates. Features of a vegetarian diet that may reduce risk of chronic disease include lower intakes of saturated fat and cholesterol and higher intakes of fruits, vegetables, whole grains, nuts, soy products, fiber, and phytochemicals. The variability of dietary practices among vegetarians makes individual assessment of dietary adequacy essential. In addition to assessing dietary adequacy, food and nutrition professionals can also play key roles in educating vegetarians about sources of specific nutrients, food purchase and preparation, and dietary modifications to meet their
Iron
The iron in plant foods is nonheme iron, which is sensitive to both inhibi- tors and enhancers of iron absorption. Inhibitors of iron absorption include phytates, calcium, and the polypheno- lics in tea, coffee, herb teas, and cocoa. Fiber only slightly inhibits iron absorp- tion (19). Some food preparation tech- niques such as soaking and sprouting beans, grains, and seeds, and the leav- ening of bread, can diminish phytate levels (20) and thereby enhance iron absorption (21,22). Other fermentation processes, such as those used to make miso and tempeh, may also improve iron bioavailability (23).
Vitamin C and other organic acids found in fruits and vegetables can substantially enhance iron absorp- tion and reduce the inhibitory effects of phytate and thereby improve iron status (24,25). Because of lower bio- availability of iron from a vegetarian diet, the recommended iron intakes for vegetarians are 1.8 times those of nonvegetarians (26).
Whereas many studies of iron ab-
sorption have been short term, there is evidence that adaptation to low in- takes takes place over the long term, and involves both increased absorp- tion and decreased losses (27,28). In- cidence of iron-deficiency anemia among vegetarians is similar to that of nonvegetarians (12,29). Although vegetarian adults have lower iron stores than nonvegetarians, their se- rum ferritin levels are usually within the normal range (29,30).