Zinc plays a key role in genetic expression, cell division, and growth and is essential for function of more than 200 enzymes. Effects of deficiency include stunting, anergy, dermatitis, poor healing, teratology, and neuropsychologic impairments. Risk of deficiency is related to level of anabolism and food choice. Bioavailability is greater from flesh foods than foods of plant origin. Pharmacologic intakes of zinc lower copper retention and impair copper-dependent processes. Pharmacologic intakes of folate impair zinc metabolism and may cause abnormal pregnancy outcomes. A recent review suggests zinc deficiency is common among populations of developing countries, particularly those that are deficient in iron.