Bone mineral content, serum vitamin D metabolite concentrations, and ultraviolet B light exposure in infants fed human milk with and without vitamin D 2 supplements

Abstract

Objective To monitor ultraviolet B light exposure in human milk-fed infants both with an without supplemental vitamin D 2, and to measure longitudinally the bone mineral content, growth, and serum concentrations of calcium, phosphorus, 25-hydroxyvitamin D 2, 25-hydroxyvitamin D 2, 1,25-dihydroxyvitamin D, and parathyrold hormone. Design Longitudinal, randomized, double-blind, placebo-controlled study of 6 months' duration. Setting Patients from private pediatric practice, Madison, Wisconsin. Patients Sequential sampling of 46 human milk-fed white infants; 24 recelved 400 IU/day of vitamin D 2, and 22 recelved placebo. An additional 12 patients were followed who received standard infant formula. Eighty-three percent of patients completed a full 6 months of the study. Measurements and results Ultraviolet B light exposure and measurements growth did not differ between groups. At 6 months, the human milk groups did not differ significantly in bone mineral content or serum concentrations of parathyroid hormone or 1,25-dihydroxyvitamin D, although total 25-hydroxyvitamin D values were significantly less in the unsupplemented human milk group (23.53±9.94 vs 36.96±11.86 ng/ml; p<0.01). However, 25-hydroxyvitamin D 3 serum concentrations were significantly higher in the unsupplemented human milk-fed group compared with the supplemented group (21.77±9.73 vs 11.74±10.27 ng/ml, p<0.01) by 6 months of age. Conclusion Unsupplemented, human milk-fed infants had no evidence of vitamin D deficiency during the first 6 months life.