Nutritional modulation of age-related changes in the immune system and risk of infection

Abstract

The immune system undergoes some adverse alterations during aging, many of which have been implicated in the increased morbidity and mortality associated with infection in the elderly. In addition to intrinsic changes to the immune system with aging, the elderly are more likely to have poor nutritional status, which further impacts the already impaired immune function. Although the elderly often have low zinc serum levels, several manifestations commonly observed during zinc deficiency are similar to the changes in immune function with aging. In the case of vitamin E, although its deficiency is rare, the intake above recommended levels is shown to enhance immune functions in the elderly and to reduce the risk of acquiring upper respiratory infections in nursing home residents. Vitamin D is a critical vitamin in bone metabolism, and its deficiency is far more common, which has been linked to increased risk of infection as demonstrated in a number of observational studies including those in the elderly. In this review, we focus on zinc, vitamin E, and vitamin D, the 3 nutrients which are relatively well documented for their roles in impacting immune function and infection in the elderly, to discuss the findings in this context reported in both the observational studies and interventional clinical trials. A perspective will be provided based on the analysis of information under review.

Regulatory role of vitamin E in the immune system and inflammation

“…Innate immune functions including NK cell activity and macrophage phagocytic capacity are also enhanced by vitamin E supplementation (26). Vitamin E supplementation appears particularly effective in improving age-associated deteriorations of immune and inflammatory responses which have been reviewed previously (9)(10)(11). Most notably, vitamin E supplementation (500 ppm dl-α-tocopheryl acetate) in old mice improved T cell mediated responses, including lymphocyte proliferation, IL-2 production and DTH response to levels comparable to those in young mice (22).…”

“…Vitamin E deficiency and supplementation have been demonstrated to affect the immune system and inflammation through various regulatory roles including alterations in membrane integrity and signal transduction, modulation of inflammatory mediators and cell cycle. Modulation of immune function by vitamin E has clinical relevance as it affects host susceptibility to bacterial and viral infection, as reviewed previously (8)(9)(10).…”

Cellular and molecular mechanisms of vitamin D in food allergy

“…Alterations in vitamin D status affect development and function of key immune cells, including the T cells, dendritic cells and regulatory T cells (Tregs). [41][42][43] This affects allergic responses through modulation of immune mediators such as IgE and pro-and anti-inflammatory cytokines.…”

The Hepatic Fate of Vitamin E

“…Consequently, two questions arise: (i) can vitamin E modulate the aging processes or prevent age-related diseases? This has been subject of several reviews [106][107][108][109]. (ii) And how is the concentration, distribution, and function of vitamin E modulated by the aging process?…”