Zinc is an essential mineral in human nutrition. Zinc is essential because it acts as a cofactor in a large number of enzymes. One of the roles of zinc is that of reproductive physiology and growth, as children with low zinc intakes can experience reduced growth and delayed sexual development. Clinical zinc deficiency is rare in Western nations, but marginal deficiencies, sometimes called insufficiencies, are through to be more common. The Western diet is devoid of meaningful levels of a number of trace elements including zinc, and this may explain the low levels of zinc reported in many studies that have investigated the zinc status of apparently healthy adults and children. In particular, elderly subjects may be at increased risk of developing marginal zinc deficiencies because nutrient absorption and food intake decreases with advancing years. Some studies have reported that up to 30 % of elderly subjects tested are deficient in zinc. The mean zinc intake of these subjects was just over half the recommended intake level.
One physiological response to low zinc intakes may be a reduction in the production of testosterone. The relationship between testosterone production in men and zinc status is not fully understood, but research suggests that marginal zinc deficiency does cause a reduction in serum testosterone levels. Researchers have investigated this association between zinc status and testosterone levels in elderly men. For example one study1 reported that serum testosterone concentrations were significantly associated with cellular (lymphocyte) zinc concentrations. In healthy young men, clinically indiced zinc deficiencies caused a significant reduction in serum testosterone concentrations after 20 weeks of zinc restriction. When elderly subjects who were zinc deficient were administered zinc supplements amounting to 30 mg elemental zinc (from zinc gluconate) for 6 months, their serum testosterone levels doubled. Zinc deficiency, even if marginal, therefore may suppress natural testosterone production in otherwise healthy men.
RdB
