[Food supplements--potential and limits: part 3].

Ageing processes are associated with physiological changes, e.g. a reduction of metabolically active body mass and an impaired hunger-satiety regulation, which--combined with chronic diseases and psychosocial problems--significantly increase the risk for malnutrition. However, considering their nutrition and health status elderly people are a very heterogeneous group. The nutrition situation of "young" seniors does generally not differ from the situation of working-age adults while institutionalized elderly people and those in need of care often show signs of a global malnutrition. The critical nutrients in the nutrition of the elderly particularly include vitamin B12 and D. Six percent of all elderly have a manifest and 10 to 30% a functional vitamin B12 deficiency. The main cause is vitamin B12 malabsorption resulting from a type B atrophic gastritis. The functional vitamin B12 deficiency and the associated hyperhomocysteinemia are risk factors for neurodegenerative diseases and accelerate bone loss. With increasing age the vitamin D status is deteriorating. About 50% of the elderly living in private households is deficient in vitamin D; in geriatrics vitamin D deficiency is more the rule than an exception. This is caused by a reduced endogenous biosynthesis, low UVB exposure and a diet low in vitamin D. A vitamin D deficiency increases the risk for falls and fractures as well as the risk for neurodegenerative diseases. Also the overall mortality is increased.