Impact of nutritional status and nutrient supplements on immune responses and incidence of infection in older individuals.

With advancing age there is a progressive decline in immune responses although this is not inevitable. The impairment in immunocompetence is noticeable as early as 35-40 years in many individuals. At the same time, some persons even in the 80s may show a vigorous immune system comparable with that of the young adult. Nutrient deficiencies are frequent in older populations. A variety of nutrients are affected: zinc, iron, beta-carotene, Vitamins B6, B12, C, D and E, ad folic acid. The causal interaction between nutritional deficiencies and impaired immunity has been known in children; a similar relationship has been postulated in the elderly. In the last 25 years, many studies employing different designs have examined the role of diet, nutritional status, and nutrient supplements in the immune responses of older individuals. Some nutrients, for example zinc and Vitamin E, have been shown to increase selected immune responses but have not been beneficial in terms of reduction in infectious morbidity. A growing consensus indicates that the use of a multinutrient containing optimum amounts of essential trace elements and vitamins is likely to result in enhanced immune responses and reduction in the occurrence of common infections. These findings have considerable fundamental, clinical and public health significance.