Prophylactic vitamin D in healthy infants: assessing the need

Abstract

The objective was to evaluate the need for vitamin D prophylaxis in healthy infants. This was a prospective and randomized study performed at primary care clinics. Eighty-eight full-term 1-month-old healthy infants were randomly assigned to receive (n = 41) or not (n = 47) 402 IU/d of vitamin D for 1 year. Primary outcome measures were serum 25-hydroxyvitamin D (25OHD) and parathyroid hormone (PTH) concentrations at 3, 6, and 12 months of age; secondary measures included data on feeding, habitat, season of birth, sun exposure, and physical examination. At 3 and 6 months of age, serum 25OHD levels (±SD) were significantly higher (P < .001) in the prophylaxis group. In the group without prophylaxis, serum 25OHD increased with age; and breast-fed infants aged 3 months had the lowest value (20.2 ± 9.4 ng/mL), which was significantly (P = .001) lower than that of formula-fed infants (35.0 ± 9.7 ng/mL). The PTH levels were not influenced by the prophylaxis or feeding. No influence of either the habitat or season of birth on serum 25OHD concentrations was demonstrated. No infant had clinical signs of vitamin D deficiency. Serum 25OHD and PTH concentrations were weakly but significantly correlated (r = -0.29, P = .009) at 3 months of age. Healthy infants without vitamin D prophylaxis had lower circulating concentrations of 25OHD at 3 and 6 months of age, the lowest value being found in 3-month breast-fed infants. The clinical relevance of these findings is probably negligible because serum 25OHD levels spontaneously increased with age and were not associated with high serum PTH. Clinical manifestations of rickets were not observed.