Vitamin D and Immunity

This chapter focuses on the current understanding of vitamin D and immunity, with special attention to the elderly. Vitamin D insufficiency and deficiency are common among the elderly population. Vitamin D plays an immunoregulatory role in innate and adaptive immunity, and low vitamin D status has been implicated in the etiology of immune disorders, such as infectious diseases as well as some autoimmune disorders. As summarized here, the aging of the immune system is well documented and indicates that both innate and adaptive immunity are impaired with increasing age. Nutritional intervention with vitamin D seems to be a valid approach to delay the deterioration of the immune system with increasing age. Based on promising results in targeting some of the impairments of the immune system in older people, supplementation with vitamin D seems to be one strategy in attempting to increase not only the lifespan but also the health span of this increasing elderly proportion of the global population.