[Significance of vitamins in nutrition counseling].

The following review summarizes important facts about the water-soluble vitamins thiamin, riboflavin, B6, B12, folate and vitamin C and the fat-soluble vitamins A, D, E and K with regard to their effects, the critical stability and the most frequent deficiencies. Water, oxygen and light are the most important factors which have the ability to destroy water-soluble vitamins. Because the first clinical signs of vitamin deficiencies are unspecific, e.g. anorexia, sleeping disturbances, little power of concentration and irritability, they are often not diagnosed early enough. Therefore, the dietitians should control and if needed alter the dietary habits in order to improve vitamin supply, in particular in elderly people, patients with long-term hospital stay, vegetarians and young women with eating disorders.