A randomised controlled trial comparing daily (400 international units) and single bolus dosing (50,000 international units) of vitamin D in healthy breastfed infants of vitamin D deficient mothers.

To assess the proportion of breastfed infants who are vitamin D sufficient (25 OH vit D > 50nmol/L) in the intervention group (bolus vitamin D dosing) versus the standard daily vitamin D dosing. This will be achieved by measurement of 25 OH vit D levels ; a marker of vitamin D status. This is an open label, single site - hospital based centre Primary: Proportion of subjects at 4 months of age with 25 OH vit D levels > 50nmol/L. Secondary: Total calcium as marker of safety, compliance, clinical markers of vitamin D deficiency Recruitment period: May – Feb 2014. Four month follow up period 1) 400 IU vitamin D daily 2) 50,000 IU at birth only (bolus) Sample size of 70 with 28 in each group + drop out rate. Term breastfed infants born to pregnant women who are found to be vitamin D deficient (25 OH vit D < 50nmol/L) at 35-37 weeks gestation