[Vitamins and nutritional supplements in older persons: How to diagnose and when to substitute?].

Despite an excellent food supply in Germany, a large percentage of older persons living at home or institutionalized older persons suffer from or are at risk for malnutrition. The purpose of this article is to highlight the association between nutrient deficiencies and age-related diseases and give rational recommendations for substitution. Both malnutrition and low levels of specific nutrients are associated with cognitive and functional impairment, dementia, and depression in older persons. Most prevalent are deficiencies in vitamin B1, vitamin B12, and vitamin D. Serum levels are often misleading and show false negative results in vitamin B1 and B12 deficiencies; therefore, determination of erythrocyte transketolase activity (ETKA) and the thiamine pyrophosphate (TPP) effect for vitamin B1 and of methylmalonic acid and holotranscobalamine for vitamin B12 is recommended. Prophylactic supplementation with vitamins is not supported by prospective trials; however, positive data from observational studies support a Mediterranean diet combined with intake of vitamins, antioxidants, and unsaturated fatty acids. Older persons should be regularly screened for malnutrition and the threshold for determination of vitamin B1, B12, and vitamin D should be low. Vitamin substitution should be reserved for proven deficits. There is now data regarding cognition from prospective trials on effects of a healthy diet combined with other life-style factors like physical and cognitive activity.