Food sources
The best food sources of zinc include shellfish (especially oysters), fish, and red meats. Other sources include whole grains, legumes, nuts, and seeds.

Health applications

• Antioxidant protection
• Immune system support
• Liver health
• Growth and tissue development
• Vision
• Fertility/reproduction
• Prostate health
• Impaired sense of taste or smell
• Wound healing/skin repair
• Mental health

Deficiency symptoms
Severe zinc deficiency is manifested by diarrhea, skin changes, hair loss, mental disturbances, and recurrent infection resulting from impaired immune function. Marginal deficiency can cause poor wound healing, increased susceptibility to infection, poor sense of taste or smell, and minor skin disorders such as acne, eczema, or psoriasis. Other conditions associated with low zinc levels include reduced appetite, impotence, infertility, liver disease, poor night vision, growth retardation, mouth ulcers, a white coating on the tongue, and halitosis.¹

Growth and development
Because zinc is required for the synthesis of RNA and DNA, it plays a crucial role in the growth and development of the body. Studies on fetal development have shown that improving the zinc status of pregnant women with low zinc levels can have a positive influence on infant birth weight² and neurological development.³ Because of its role in bone and muscle formation, it is important that children have adequate zinc intake to ensure optimal growth.

Zinc and the senses
Zinc plays important roles in the senses of vision, taste, and smell. Alterations in smell and taste are among the most commonly reported manifestations of mild zinc deficiency, and these abnormalities will typically reverse with zinc supplementation. Because zinc is required for vitamin A metabolism, it is essential for good vision. Poor night vision is a common symptom of mild zinc deficiency, and low zinc levels are also associated with eye disorders like macular degeneration and retinitis pigmentosa.^4,5

Liver health
The liver depends on healthy zinc levels to function properly. Zinc is a crucial component of the antioxidant enzyme superoxide dismutase, which helps defend liver tissues from free-radical induced damage. Zinc deficiency and alterations in zinc metabolism are common in cirrhosis patients,^6,7 and long term zinc supplementation may improve glucose utilization in patients with diabetes or cirrhosis.⁸ Zinc also helps normalize copper levels in people with Wilson's disease, a disorder in which toxic accumulations of copper contribute to a variety of liver disorders.⁹

The immune system
Zinc is essential for healthy immune function, thanks largely to its roles in the body's antioxidant defense mechanisms. In developing countries, zinc deficiency has been associated with impaired immune function and increased susceptibility to respiratory infections,¹⁰ and research has shown that zinc supplementation can improve cellular immune status.¹¹ Zinc gluconate lozenges are a popular cold remedy, and studies have indicated that they can help lessen the duration and severity of cold symptoms.^12-16

The prostate gland
Zinc's influence on cellular immune status appears to play a key role in prostate health. Normal prostate cells have high concentrations of zinc, whereas cancerous prostate cells have markedly decreased levels.^17-19 Because reduction of zinc levels in prostate cells usually precedes the development of carcinoma, measurement of prostatic zinc levels may serve as an index for early detection of prostate cancer and may be of value in monitoring the progress of the disease.²⁰

Dosage/Toxicity
For general health, the common dosage range for zinc supplementation is 15 to 20 mg per day. For specific health concerns, the dosage range is 30 to 60 mg for men and 30 to 45 mg for women. Intake above 150 mg per day may result in toxic effects such as copper-deficiency anemia and depressed immune function.¹