Zinc deficiency can result in loss of appetite, impaired immune system function and slowed growth in general. Severe deficiency can cause hair loss, eye and skin problems, diarrhea, weight loss, and hypogonadism and impotence in men. Zinc deficiency isn't common in developed countries, and it's difficult to detect because the amount of zinc in the blood doesn't really represent the amount of zinc in the cells. Zinc deficiency may be due to a lack of zinc in the diet or problems with zinc absorption. People with inflammatory bowel diseases (IBD) or certain types of gastrointestinal surgery may have difficulty absorbing zinc. Pregnant women may be at a greater risk because the fetus requires large amounts of zinc. Vegetarians may require more zinc because many of the plant sources of zinc are high in phytates, which reduce absorbability.
Overdosing on zinc supplements can cause nausea, vomiting, cramps, diarrhea and headaches. Taking more than the tolerable upper intake (40 milligrams in adults) over time can cause problems with copper and iron, damage the immune system and reduce HDL cholesterol levels. Zinc supplements can also interact with certain types of medications. If you have zinc deficiency symptoms, you need to see a healthcare provider who can order blood tests to determine if that's the problem or if there are other causes.
Sources:
Office of Dietary Supplements, National Institute of Health, "Dietary Supplement Fact Sheet: Zinc." Accessed June 8, 2011. http://ods.od.nih.gov/factsheets/Zinc-HealthProfessional/.
