T cell function often declines with aging. Zinc is an important nutrient for the regulation of immune response. Supplementation of zinc might have the potential to improve the serum zinc concentrations and immunity of elderly people who have a low serum zinc concentration.

The main objective of this study is to determine the effect of supplementation of 30 mg zinc daily for 3 months on serum zinc concentrations of zinc-deficient elderly people of a nursing home. A randomized, double-blind, placebo-controlled study was conducted. Out of 53 nursing home elderly individuals (aged ≥65 y) who had met the eligibility criteria, 58% had a low serum zinc concentration i.e. serum zinc <70 μg/dL). 31 elderly were randomly given zinc (30 mg Zn/d) (n = 16) or placebo (5 mg Zn/d) (n = 15) groups. The primary result measure was of change in serum zinc concentrations between baseline and third month. The effects of supplementation on immune response were also explored. The baseline characteristics were similar in both groups.

The results of the study showed the difference in the mean change in serum zinc and it was significantly higher, by almost 16%, in the zinc group as compared in the placebo group. Supplementation of zinc has also significantly increased anti-CD3/CD28 and phytohemagglutinin-stimulated T cell proliferation along with the number of peripheral T cells. The results suggested that the zinc-induced enhancement of T cell proliferation was mostly due to an increase in the number of T cells.

In conclusion, zinc supplementation at 30 mg/day for 3 months is effective in increasing serum zinc concentrations in nursing home elderly populations. However, not all zinc-deficient elderly individuals reached sufficient concentrations. The increase in serum zinc concentration was also associated with the improvement of T cell function mostly due to an increase in the number of T cells.

Source: Am J Clin Nutr. 2016; 103(3):942-951.