[Fortified milk and supplements of oral vitamin D. Comparison of the effect of two doses of vitamin D (500 and 1,000 UI/d) during the first trimester of life].

BACKGROUND: Administration of oral vitamin D supplements has been the usual strategy used in France for the prevention of rickets. But this strategy needs reevaluation since the fortification of infant formulas with vitamin D is authorized in this country. We report the effects of oral daily supplements of vitamin D on the calcium metabolism and vitamin D status of infants receiving or not fortified milk during the first trimester of life.

POPULATION AND METHODS: Circulating levels of 25-hydroxyvitamin D (25-(OH)D) were measured: 1) in 64 infants aged 1 to 4 months, seen as outpatients between February and October, given oral vitamin D2 (theoretically 1,000 IU/d) and fed infant formulas, fortified or not with vitamin D; 2) in healthy neonates born to unsupplemented (n = 48) or supplemented vitamin D mothers (n = 22), between April and July, followed from birth (n = 70) to 3 months of age (n = 52), fed fortified milk, and given either 500 or 1,000 IU/D of vitamin D2. Serum calcium, phosphate, intact parathyroid hormone levels and alkaline phosphatase activities were simultaneously measured in this second study.

RESULTS: In the first study, the infants who had been seen during the summer and fed fortified milk had 25-(OH)D levels higher than those seen during the winter and fed the unfortified formulas (37.0 +/- 11.2 ng/mL vs 29.1 +/- 9.7 ng/mL, P = 0.013). But when daily supplements of vitamin D2 were strictly controlled (second study), all infants fed the fortified milk had 25-(OH)D levels within the adult range (10 to 37 ng/mL) at 1 and 3 months of age, whatever their vitamin D status at birth and although these infants were seen during the summer. No difference was found between infants given 500 or 1,000 IU/d as regards their mean serum calcium, phosphate and alkaline phosphatase activities. In addition, the percentage of infants with calcemia above 2.60 mM/L was even lower with the 1,000 IU/d vitamin D dosage than with the 500 IU/d dosage.

CONCLUSIONS: Daily supplements of vitamin D2 (500 to 1,000 IU/d) during the first trimester of life do not appear to induce a significant vitamin D overload when fortified milk is given to the infants. These supplementations may thus be maintained, especially when neonates are at risk of vitamin D deficiency.