Vitamin D status found to be Sufficient in Full-term exclusi
Many international medical organizations recommend vitamin D supplementation for infants, especially exclusively breastfed infants.

Full-term, exclusively breastfed infants were randomized into two groups at 2 months of age to continue exclusive breastfeeding either without vitamin D supplementation or with vitamin D3 supplementation at 400 IU/day until 6 months of age. At 6 months, the serum vitamin D (25OHD) of the infants and their mothers, serum bone marker, and infants’ growth parameters were compared between the two groups.

--The infants’ serum 25OHD concentration was lower in the control group than intervention group.

--More infants had vitamin D sufficiency in the intervention group than control group.

--There were no significant differences in the maternal 25OHD concentrations between the control and intervention groups.

--Serum calcium, phosphorus, intact parathyroid hormone, alkaline phosphatase, and infants’ growth parameters were comparable between the two groups. After adjustment for the confounding factors, 25OHD concentration in the intervention group was 25.66 ng/mL higher than the control group.

--Vitamin D supplement contributed to an 88.7% decrease in the prevalence of vitamin D insufficiency/deficiency.

Conclusively, by 6 months of age, most full-term, exclusively breastfed Thai newborns have serum vitamin D levels that are insufficient. Supplementing with 400 IU of vitamin D per day, on the other hand, improves their vitamin D status and avoids vitamin D deficiency.