Zinc metabolism and immune function in healthy elderly people.

Changes in immune function have been described in the elderly, and zinc is known to influence immune parameters. Zinc supplementation has, however, produced contradictory results. We evaluated zinc metabolism and immunity in 15 healthy noninstitutionalised elderly people on a self-selected diet and compared the results with those obtained from 10 young healthy subjects. The elderly subjects had reduced serum zinc levels and their zinc absorption values were lower than in the young subjects. Circulating immune parameters were within the normal range, while delayed immune response was altered in 8 of the 15 elderly subjects. Zinc supplementation (25 mg/day) did not result in a significant improvement in dermal hypersensitivity responses although some effect was seen in 5 cases. It is concluded that zinc supplementation is unnecessary in elderly healthy subjects even if they present zinc metabolism alterations, but may be indicated in the presence of disease.