There is a substantial relationship between zinc deficiency and anorexia, but, as in the case of iron, the relationship is complex, and you should check with your doctor before ingesting any supplements.
According to the British medical organization Foresight , zinc is an essential trace element required for bodily growth, neural function, brain development, and reproduction. Foresight also notes that zinc plays important roles in fighting viruses, bacteria, funguses, and cancer.
United Nations University (U.N.U.) observes that zinc is found in protein-rich foods, including whole grains, meat, fish, and shellfish. U.N.U. notes that vegetarians frequently have trouble getting enough zinc in their diets, a fact with important ramifications for many anorexics.
According to an article in the International Journal of Eating Disorders (1993 Mar; 13(2):229-233), half of all anorexia nervosa patients are vegetarians, which may increase their risk for zinc deficiency. A study reported therein found that 9 outpatient, vegetarian anorexics had significantly lower dietary intakes of zinc, fat, and protein than 11 non-vegetarian anorexics. The researchers conclude that zinc intake should be evaluated in all vegetarians suffering from anorexia nervosa.
The noted medical nutritionist Dr. Andrew Weil recommends 30 mg of zinc per day for people on vegetarian and semi-vegetarian diets. He uses zinc picolinate, which is rapidly absorbed by the body. However, Weil stresses that nobody should ingest more than 100 mg a day because large doses of zinc can weaken the immune system. Regarding dietary sources of zinc for vegetarians, Weil recommends legumes such as dried beans, garbanzos, peas, lentils, and soy. According to Foresight, the U.S. RDA (recommended daily allowance) of zinc for most adults is 15 mg, and for pregnant women it is 20 mg.
A case study reported in Gastroenterology Japan (1992 Aug.; 27(4):554-558) suggests that zinc supplementation may be a therapeutic option for anorexics suffering from gastric disturbances. A 16 year-old anorexic was hospitalized with vomiting and diarrhea. Tests indicated a zinc deficiency. She received intravenous zinc of 40 micromoles/day (a mole is the number of grams equal to the molecular weight of a substance) for a week, and 15 mg of zinc orally for another 60 days. After two days of intravenous treatment, her gastric symptoms disappeared, and her poundage started increasing. After a month of oral supplementation, she regained her normal weight.
According to Foresight, laboratory experiments have shown that zinc-deprived rats consumed 30 percent less food than their zinc-fed counterparts. Research on this subject, reported in a 1998 press release by the University of Illinois At Urbana-Champaign, is intriguing. According to the release, research published by Professor Neil F. Shay in Nutritional Biochemistry (Jan. 1998) and the Journal of Nutrition (Jan., July 1998), shows a rise in neuropeptide Y (NPY) in the brains of zinc-deprived rats. According to the release, NPY is a protein with appetite-stimulating properties. Shay had theorized that NPY levels would decrease; instead they increased, but the higher NPY levels did not stimulate appetite. The release says that “Shay theorizes that zinc deficiency affects the processing capabilities of NPY and negatively impairs its normal appetite-stimulating effect.”
The research, however, is far from conclusive, and rats are not people. U.N.U. notes that while anorexia has been observed in humans with severe zinc deficiency, the condition is relatively rare. According to U.N.U., there have been few human studies, and severe deprivation was not employed in those experiments. In addition, mild to moderate zinc deprivation does not produce anorexia in laboratory animals, according to U.N.U. In fact, increased appetite is often observed under such conditions.
Part of the problem in solving this puzzle, according to U.N.U., involves a “chicken and egg” question. Food-deprived animals do not get enough zinc (and many other essential nutrients). Severely zinc-deprived animals will be food-deprived due to anorexia. According to U.N.U., the research is inconclusive as to which causes the anorexia, the zinc deprivation, lack of some other nutrient due to food deprivation, or perhaps food deprivation itself. Similarly, notes U.N.U., there is an association between anorexia nervosa and zinc deficiency in malnourished children (mean age, 11.6 years), but the causative factor has not yet been determined.