Zinc is an essential trace element required for theactivity of over 300 enzymes and is involved in mostmajor metabolic pathways. Zinc participates not onlyin catalytic processes, but also in the structure andstability of some regulatory proteins.
General signs of human zinc deficiency indicate thatzinc has important functions in maintaining immunefunction, reproduction, healthy skin, and growth.Numerous studies support the fundamental role ofzinc for normal immune response in humans.Immune cells must be able to rapidly divide in orderto respond to daily challenges. Like all rapidlydividing cells, immune cells depend on adequateamounts of dietary zinc.
As a cofactor of the antioxidant enzyme superoxidedismutase (SOD), zinc can be considered an antioxidantnutrient. Zinc supplementation has been shown toincrease the antioxidant activity of SOD, and provideincreased free radical protection. Zinc deficiency isassociated with increased oxidative damage.Absorption of toxic heavy metals, especiallycadmium and lead, is lower in individuals with highzinc status compared to those with low zinc status.The body pool of readily available zinc appears to besmall, which renders the body susceptible todeficiency and therefore dependent on a steadydietary supply of bioavailable zinc. While typicalzinc intakes in U.S. adults are between 10 and 15 mgper day, which approach the RDA, intakes in theelderly are often low. Pregnant women are also atrisk for zinc deficiency, since they have a higherrequirement for this trace element.Frequently, vegetarians and chronically depressedindividuals have been found to have low zinc status.