Inadequate vitamin D may cause rickets in children, while inadequate calcium can contribute to risk of osteoporosis in later years. These vegetarians are susceptible to iron deficiency anemia because they are not only missing the more readily absorbed iron from animal flesh, they are also likely to be eating many foods with constituents that inhibit iron absorption-soy protein, bran, and fiber, for instance. Vegans must guard against inadequate calorie intake, which during pregnancy can lead to low birth weight, and against protein deficiency, which in children can impair growth and in adults can cause loss of hair and muscle mass and abnormal accumulation of fluid. The Institute of Food Technologists, in the July 1991 issue of its journal, Food Technology, describes six types of vegetarians. According to the Institute of Food Technologists and the American Dietetic Association, if appropriately planned, vegan diets can provide adequate nutrition even for children.
Some experts disagree.
Gretchen Hill, Ph.D., associate professor of food science and human nutrition at the University of Missouri, Columbia, believes it's unhealthy for children to eat no red meat. While meat is well-known as an important source of iron, Hill says it may be even more valuable for copper and zinc. Copper not only helps build the body's immunity, it builds red blood cells and strengthens blood vessels. Children can't meet their zinc needs without eating meat. Also, vegetarian women of childbearing age have an increased chance of menstrual irregularities, Ann Pedersen and others reported last year in the American Journal of Clinical Nutrition.