Vitamin D in children and adolescents.

Vitamin D is essential for bone growth and development in children and adolescents. Vitamin D deficiency leads to rickets, characterized by defective bone formation, in infants and children. Vitamin D prophylaxis during the first years of life has empirically shown to be effective in combating rickets in infants in some countries. Vitamin D insufficiency can have negative effects on bone health in older children and in adolescents. Vitamin D supplementation has been shown to have an effect on bone mineral density at least in vitamin D deprived older children and adolescents but not in those with a normal vitamin D status. A good vitamin D status during pregnancy seems to be important for bone health in the off-spring later in life, but randomized controlled studies are needed to establish an effect of vitamin D during pregnancy on bone and other health outcomes in the offspring. Vitamin D supplementation during childhood may offer protection against diabetes type 1, but randomized controlled trials are needed to ascertain causality.