Laits enrichis et suppléments oraux en vitamine D. Comparaison de l'effet de deux doses de vitamine D (500 et 1000 UI/j) pendant le premier trimestre de la vie

Abstract

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 (theorically 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 normal 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.