Is vitamin D supplementation necessary in healthy full-term breastfed infants? A follow-up study of bone mineralization in healthy full-term infants with and without supplemental vitamin D.

AIM: The aim of the study is to establish whether healthy full-term breastfed infants require supplemental vitamin D for proper bone mineralization.

METHODS: Bone mineralization was studied by performing ultrasound scans of 73 healthy full-term subjects at the age of 3 months. The infants were divided into three groups. Group A: breastfed without supplemental vitamin D (BF); group B: breastfed with supplement of 400 IU/day of vitamin D (BFD); group C: fed with formula (with and without supplemental vitamin D 400 IU/day) (FF). The values of mcSOS (m/sec) and mcBTT (µsec) were assessed in all subjects.

RESULTS: A statistically significant difference has been found between group A vs group B both in mcSOS (P=0.03) and in mcBTT (P=0.01) values and also between group A vs group C both in mcSOS (P=0.012) and in mcBTT (P=0.003) values. Significant differences between group B vs group C were not found. In 75% of subjects of group A mcSOS and mcBTT values were ≤ the 10th percentile, while in group B they were between the 10th and 50th percentile. In FF infants given supplemental vitamin D mcSOS and mcBTT values were between the 25th and 75th percentile.

CONCLUSION: Human breast milk is an appropriate source of nutrition for the growth of healthy full-term newborns, but is poor in vitamin D as demonstrated by the impaired bone mineralization in the breastfed infants without supplemental vitamin D. The results presented demonstrate that exclusively breastfed infants require at least 400 IU/day of supplemental vitamin D.