How Vitamins influence Immune Function - Nutritional Influences on Illness - Brief Article

Townsend Letter for Doctors and Patients,  April, 2002  by Melvyn R. Werbach

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A deficiency of most vitamins may impair immune system function. Also, an elevated intake of certain vitamins may have either immunostimulating or immunosuppressive effects.

Vitamin A

Vitamin A deficiency has been called an immunodeficiency disorder characterized by widespread alterations in immunity (Semba, 1994). Supplementation may reverse post-operative immunosuppression (Cohen) and boost immune responses in the elderly, persons with parasitic infections, and persons with a high exposure to ultraviolet light (Rumore). Moreover, animal work suggests that it may enhance responses to weak immunogens and reverse immunosuppression (Nuwayri-Salti).

However, an excess of vitamin A may depress the very immune responses that are stimulated by modest increases of the vitamin (Levy). In a double-blind study of institutionalized elderly, only 800 micrograms daily (about 2,700 IU) reduced the number of both CD3+ and CD4+ T-lymphocytes (Fortes), suggesting that vitamin A supplements should be used cautiously in this population.

Vitamin B Complex

Deficiencies of various B-complex vitamins are associated with decreased antibody responses and impaired cellular immunity (Anderson, 1983). Also, in controlled studies, supplementation of a combination of vitamins B1, B6 and B12 has been shown to reduce postoperative immunosuppression (Kurashige).

Vitamin C

Deficiency of vitamin C impairs phagocyte function and cellular immunity (Chandra, 1986). This includes inhibition of neutrophil mobility -- which, in turn, inhibits the formation of inflammatory reactions (Beisel, 1987) -- and decreased natural killer cell activity (Dowd).

Studies of megadose vitamin C supplementation in healthy individuals have found the supplement to bolster both cellular and humoral immunity. However, when mice were stressed and then supplemented with megadose vitamin C, they developed severe lymphopenia. Since stress abruptly increases adrenal corticosteroids in plasma following the release of vitamin C by the adrenals, the authors theorize that large doses of the vitamin may maintain high levels of plasma corticosteroids which, in turn, may reduce the organism's immune response when stressed (Richardson) -- although, in humans, lymphopenia due to megadose ascorbate has not been reported.

Vitamin D

In its active form (1,25-dihydroxyvitamin D3), vitamin D is an autoregulatory hormone which has been shown in vitro to modulate lymphocyte and macrophage functions. While it has no apparent effect on B-lymphocytes, it causes T-cell suppression which indirectly inhibits antibody production by B-cells (Muller).

Vitamin E

A deficiency of vitamin E depresses immunoglobulin response to antigens, lymphocytic proliferative responses to mitogens and antigens, delayed dermal hypersensitivity reactions, and general host resistance (Beisel, 1981).

Supplementation may enhance immune responses by increasing the number of antibody-forming cells and cell-mediated responses (Levy). To determine whether long-term supplementation enhances clinically relevant measures of immunity in the healthy elderly, subjects received 60 mg, 200 mg or 800 mg vitamin E for 235 days in a double-blind study.

While immunoglobulin levels and levels of T- and B-cells were unaffected, certain clinically relevant indices of cell-mediated immunity improved at the 200 mg dosage level, suggesting that the elderly may benefit from higher levels of vitamin E intake than those usually recommended (Meydani, 1997). Similar findings have been noted with healthy young subjects (Meydani, 1993).

References

Anderson R, Theron A. Effects of B-complex vitamins an cellular and humoral immune functions in vitro and in vivo. Int J Vitam Nutr Res 24:7-84, 1983

Beisel WR et al. Single-nutrient effects en immunologic functions. JAMA 245(1):53-8, 1981

Beisel WR. Role of nutrition in immune system diseases. Compr Ther 13(1):13-19, 1987

Chandra RK. Nutrition and immunity -- Basic considerations. Part I. Contemp Nutr 11(11), 1986

Cohen B et al. Reversal of postoperative immunosuppression in man by vitamin A. Surg Gynecol Obstet 149:688-62, 1979

Dowd PS et al. Nutrition and cellular immunity in hospital patients. Br J Nutr 55(3):515-27, 1986

Fortes C et al. The effect of zinc and vitamin A supplementation on immune response in an older population. J Am Geriatr Soc 46(1):19-26, 1998

Johnston CS et al. Antihistamine effect of supplemental ascorbic acid and neutrophil chemotaxis. J Am Coll Nutr 11(2):172-6, 1992

Kurashige S et al. Effect of vitamin B complex on the immunodeficiency produced by surgery of gastric cancer patients. Jpn J Exp Med 58(4):197-202, 1988

Levy JA. Nutrition and the immune system, in DP Stites et al, Eds. Basic and Clinical Immunology. 4th Edition. Los Altos, CA. Lange Medical Publications, 1982:297-305

Meydani M et al. Effect of long-term vitamin E supplementation on lipid peroxidation and immune responses of young and old subjects. Abstract. FASEB J:A415, 1993

Meydani SN at al. Vitamin E supplementation and in vivo immune response in healthy elderly subjects. JAMA 277(17):1380-6, 1997