[Importance of and need for vitamins in old age].

Vitamins may modulate primary as well as secondary processes of aging. On the other hand, vitamin metabolism itself may be modified by the process of aging or by various chronic diseases connected with aging. On the basis of these multiple interactions the question arises whether the demand for individual vitamins is altered as a consequence of aging. Age-dependent metabolic changes may alter the need for individual vitamins. This is the case for vitamin D, vitamin B6, Riboflavine, and in special subpopulations for vitamin B12. The most important source for a sufficient supply of vitamins is an adequate nutrition. Thus, besides the aforementioned vitamins, insufficient alimentary intake with food plays the most important role in vitamin deficiency in the elderly. Due to age-specific alterations of the vitamin-A metabolism, toxicity of vitamin-A plays a more important role than vitamin-A deficiency. The vitamins A and D as well as vitamin C are discussed in detail.