<unk>  is defined either as insufficient zinc to meet the needs of the body, or as a serum zinc level below the normal range. However, since a decrease in the serum concentration is only detectable after long-term or severe depletion, serum zinc is not a reliable biomarker for zinc status. Common symptoms include increased rates of diarrhea.<unk>  affects the skin and gastrointestinal tract; brain and central nervous system, immune, skeletal, and reproductive systems.<unk>  in humans is caused by reduced dietary intake, inadequate absorption, increased loss, or increased body system use. The most common cause is reduced dietary intake. In the U.S., the Recommended Dietary Allowance (RDA) is 8 mg/day for women and 11 mg/day for men. The highest concentration of dietary zinc is found in oysters, meat, beans, and nuts. Increasing the amount of zinc in the soil and thus in crops and animals is an effective preventive measure.<unk>  may affect up to 2 billion people worldwide.
Zinc deficiency
Zinc toxicity
Manganese deficiency 
Boron deficiency 
Lead poisoning
Iron deficiency
Selenium deficiency
Copper deficiency