Nutrition concerns and health effects of vegetarian diets. Vegetarians exhibit a wide diversity of dietary practices, often described by what is omitted from their diet. When a vegetarian diet is appropriately planned and includes fortified foods, it can be nutritionally adequate for adults and children and can promote health and lower the risk of major chronic diseases. The nutrients of concern in the diet of vegetarians include vitamin B(12), vitamin D, ω-3 fatty acids, calcium, iron, and zinc. Read more about Nutrition concerns and health effects of vegetarian diets.