Role of Vitamin E in Supplements
Two studies that administered supplements (100-800 mg/day) for at least 6 months found an enhancement of several immune parameters including dihydrotestosterone (DTH) response, mitogen-induced IL-2 production, and increased antibody titer to hepatitis B and tetanus vaccine One of these studies found optimal results in those subjects receiving 200 mg/day of vitamin E, but higher levels of vitamin E (800 mg/day) were not associated with an additional improvement of immune response.
The results from one study failed to find an enhancement of immune response in elderly subjects consuming 100 mg/day. However, in this study, subjects received the supplement for only 3 months and perhaps a longer period of supplementation is necessary to observe an effect. The results from two additional studies found enhancement of several immune parameters (LPS-induced production of IL-1, TNFa, mitogen-induced lymphocyte proliferation, neutrophil phagocytosis) when vitamin C (1 g/day) and vitamin E (200-400 mg/day) were administered to healthy young and elderly adults. The mechanisms by which vitamin E supplementation may alter immune response remain to be established.
Currently, it is thought that one potential mechanism may involve the production of prostaglandin E 2 (PGE 2 ). PGE 2 , produced by macrophages, is known to suppress some lymphocyte responses. Some recent evidence suggests that aged animals fed additional vitamin E have a reduction of macrophage PGE 2 production. The immune response may be enhanced through the reduction of PGE 2. Further research on potential mechanisms will provide important information with respect to an understanding of vitamin E-associated immunomodulation.
Immune Effects and Exercise
Although vitamin E has been studied in relation to exercise, most studies have focused on the potential antioxidant effects of vitamin E supplementation. Others have examined various physiological changes regarding vitamin E supplementation and exercise and found no change in neuroendocrine profile but a slight reduction in the incidence of gastrointestinal complications in those marathon runners consuming vitamin E for 2 weeks before the race. The only study we are aware of that examined immunity and vitamin E supplementation with exercise found that vitamin E and C supplementation before competing in an ultramarathon reduced the incidence of URI symptoms in the postrace period.
However, it was thought that this effect was related to vitamin C rather than vitamin E because the post-race reduction in symptoms of URI was not lower with vitamin E + C than vitamin C alone. To our knowledge, we are not aware of any studies that have explored potential associations between vitamin E supplementation alone and immune response in regards to exercise. Perhaps this area of research may show some promise in the elderly.