Breast-fed infants who took either ergocalciferol or cholecalciferol daily for 3 months had similar changes in plasma 25-hydroxyvitamin D levels.

Daily supplementation with 10 μg of either ergocalciferol (D2) or cholecalciferol (D3) resulted in an increase in plasma 25-hydroxyvitamin D concentrations without significant differences between the two forms.

• At baseline, 23% of infants were vitamin D deficient (≤24.9 nmol/L), which decreased to 2% at follow-up.
• The increase in total 25-hydroxyvitamin D concentration was 17.6 ± 26.7 nmol/L for the D2 group and 22.2 ± 20.2 nmol/L for the D3 group, with no significant difference observed.
• A total of 86% of infants achieved the 50 nmol/L cutoff, with 75% from the D2 group and 96% from the D3 group meeting this level (P < 0.05).
• The baseline plasma 25-hydroxyvitamin D concentration was inversely related to the change in total 25-hydroxyvitamin D (r = -0.52; P < 0.001).
• No differences in compliance, breastfeeding rates, or sun exposure were noted among the groups.

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