Zinc is an essential trace mineral needed to catalyze more than 100 enzymatic processes. Zinc is necessary for many bodily functions, including conversion of retinol to retinal, which is needed for night vision; absorption of gastrointestinal folate; and synthesis and stabilization of DNA and RNA. Deficiencies cause deleterious health effects, so adequate intake is important. However, zinc intakes above a certain level can be toxic.
Zinc Requirements
The RDA for zinc is 11 mg per day for adult males and 8 mg per day for adult females 19 to 30 years of age. Your body does not store zinc, so your diet needs to have a steady supply. Deficiencies in zinc increase risk for stunted growth, poor wound healing, decreased sense of taste, weakened immune response and night blindness.
Roles in Metabolism, Immunity and Cancer
Zinc deficiency lessens insulin response and may result in impaired glucose tolerance, increasing risk for developing type 2 diabetes. Basal metabolic rate may decrease in response to decreases or deficiency in zinc. Further, impaired immune response can result from inadequate zinc intake. Zinc assists in the production of some white blood cell types, which are essential in fighting infection. This mineral also reduces the carcinogenic potential of some cells, and may decrease risk of prostate and colorectal cancer.
Zinc Functions in Wound Healing
Zinc functions in skin integrity and wound healing, which is likely related to its role in protein synthesis. Topical ointments containing zinc, used widely in hospital settings, aid in healing pressure ulcers, surgical wounds and burns. Zinc oxide preparations decrease post-surgical pain and healing times, and minimize the amount of wound care patients need when recovering from surgery on the lower extremities.
Zinc Toxicity
Avoid taking mega-doses of zinc supplements to get extra benefits. Copper and iron deficiency can result from excess zinc. Further, intranasal zinc can irreversibly damage nasal nerve receptors and cause loss of smell, or anosmia. Adults should limit intake of zinc to 40 mg per day to prevent zinc toxicity.
References
- "Dermatologic Surgery"; Enhanced Healing of Surgical Wounds of the Lower Leg Using Weekly Zinc Oxide Compression Dressings; W.G. Stebbins, et al; February 2011
- "International Journal of Environmental Research and Public Health"; The Essential Toxin: Impact of Zinc on Human Health; L.M. Plum, et al; April 2010
- "PLoS One"; ZIC1 Is Downregulated through Promoter Hypermethylation, and Functions as a Tumor Suppressor Gene in Colorectal Cancer; G. Lihong, et al; February 2011
- Dietary Reference Intakes (DRIs): Tolerable Upper Intake Levels, Elements"; Food and Nutrition Board Institute of Medicine
- Dietary Reference Intakes (DRIs): Recommended Dietary Allowances and Adequate Intakes, Vitamins"; Food and Nutrition Board Institute of Medicine
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