[Nutrition and health--vitamins and vitamin supplements]

A balanced diet based on the Guidelines of the Netherlands Nutrition Centre provides a suitable basis for the maintenance of good health. However, there are a number of situations where supplementation with vitamins is clearly indicated. These include infants (vitamin A, D and K), young children, and pregnant and lactating women (vitamin D), future expectant mothers (folic acid) and the elderly (vitamin D). If doubts exist about a sufficient vitamin intake via the regular diet, a daily supplement supplying all vitamins at the level of the recommended daily allowance (RDA) is considered to be a responsible and safe choice. Epidemiological research indicates that the incidence of certain diseases is lower if the intake of vitamins is significantly higher than the RDA. However to date, targeted intervention studies have provided little unequivocal evidence to support this argument. For certain vitamins (A, D, folic acid, B6, nicotinic acid and beta-carotene) excessive intakes are associated with a health risk or clear toxicity. In the case of vitamin B6, nicotinic acid, folic acid and beta-carotene this risk is mainly limited to the use of high-dose supplements.