Nutritional aspects of calcium and vitamin D from infancy to adolescence

Calcium is an essential nutrient for normal growth and development. Growing individuals must be in positive calcium balance to satisfy their calcium needs. Calcium requirements are higher during infancy and adolescence than childhood and adulthood. The achievement of a higher calcium balance in infancy and adolescence is likely due to the increased serum 1,25-dihydroxyvitamin D concentration occurring during these periods. The main determinants of calcium balance in infancy are dietary calcium intake and vitamin D. In normal circumstances, breast milk and formulas supply sufficient amounts of calcium. In the post-natal life, the major sources of vitamin D are sunlight exposure and supplemented formulas; in fact, the amount of vitamin D in breast milk, cow's milk, and common foods is poor. Although sunlight exposure should be able to maintain adequate vitamin D stores, a supplement with 400 IU/day of vitamin D from birth to the second year of life is recommended to assure the prophylaxis of rickets in all breast-fed infants. A dose of 400 IU/day of vitamin D is safe and appropriate. During childhood and adolescence, currently recommended dietary allowances (RDA) for calcium might be augmented, as suggested by calcium balance studies. The higher amount of calcium intake may lead to achieve maximal peak bone mass. The main source of vitamin D in children and adolescents is the casual sunlight exposure; therefore, a sistematical vitamin D supplementation is not usually needed. The major sources of calcium are milk and dairy products. However, if calcium intake is reduced, an additional calcium intake to reach the RDA may be provided by calcium supplements.