Impact of vitamin E on immune function and its clinical implications.

Vitamin E is a chain-breaking antioxidant that protects membranes from free-radical damage. Evidence suggests significant impact of vitamin E on the modulation of immune functions. Results from animal and human studies indicate that vitamin E deficiency impairs both humoral and cell-mediated immune functions. Supplementation of vitamin E above the recommended levels has been shown to enhance immune functions and to be associated with increased resistance against several pathogens, especially in the aged. The current vitamin E consumption status from diets, the status of vitamin E supplement use, the effects of vitamin E on different aspects of immune functions and mechanisms of its action and the clinical significance of vitamin E supplementation will be reviewed.