Zinc: The Biology and Therapeutics of an Ion

Although the role of zinc in the growth of microorganisms, plants, and animals was well established many decades ago, its role in humans was first recognized only in 1963 [1]. Our studies from the Middle East showed, for the first time, that zinc deficiency occurs in humans [1]. In 1974, the Food and Nutrition Board of the National Research Council of the National Academy of Sciences [2] made a landmark decision to establish a recommended dietary allowance for zinc as an essential element for humans.

The clinical manifestations of zinc deficiency in humans include growth retardation, male hypogonadism, skin changes, poor appetite, mental lethargy, abnormal neurosensory changes, delayed wound healing, and susceptibility to infection [3-5]. Zinc supplementation completely corrects all of these manifestations [3-5].

Nutritional zinc deficiency is prevalent throughout the world. Zinc deficiency in children has been reported from at least a dozen countries (including the United States) on all continents [6, 7]. The cereal proteins consumed by persons in developing countries contain large quantities of phytates, organic compounds that bind dietary zinc and iron and render them unavailable for absorption [4]. It is therefore not surprising that iron-deficiency anemia and zinc deficiency coexist in most developing countries and that these deficiencies are common problems throughout the world [4-6]. Zinc and iron in red meat are readily available for absorption. However, the Western world's shift away from consumption of red meat and toward consumption of cereal proteins containing high phytate levels may be conducive to the development of mild …