The Effect of High-Dose Vitamin D Supplementation on Serum Vitamin D Levels and Milk Calcium Concentration in Lactating Women and Their Infants
LAURA A. BASILE, SARAH N. TAYLOR, CAROL L. WAGNER, RON L. HORST and BRUCE W. HOLLIS
Breastfeeding Medicine Mar 2006, Vol. 1, No. 1: 27-35.
Objective: Improve vitamin D status in lactating women and their recipient infants, and measure breast milk calcium concentration [Ca] as a function of vitamin D regimen.
Design/Methods: Fully breastfeeding mothers were randomized at 1 month postpartum to 2000 (n = 12) or 4000 (n = 13) IU/day vitamin D for 3 months to achieve optimal vitamin D status [serum 25(OH)D ≥ 32 ng/mL (80 nmol/L)]. Breast milk [Ca], maternal and infant serum 25(OH)D and serum Ca, and maternal urinary Ca/Cr ratio were measured monthly.
Results: Mothers were similar between groups for age, race, gestation, and birth weight. 25(OH)D increased from 1 to 4 months in both groups (mean ± SD): +11.5± 2.3 ng/mL for group 2000 (p = 0.002) and +14.4±3.0 ng/mL for group 4000 (p = 0.0008). The 4000 IU/day regimen was more effective in raising both maternal and infant serum levels and breast milk antirachitic activity than the 2000 IU/day regimen. Breast milk [Ca] fell with continued lactation through 4 months in the 2000 and 4000 IU groups. Decline in breast milk [Ca] was not associated with vitamin D dose (p = 0.73) or maternal 25(OH)D (p = 0.94). No mother or infant experienced vitamin D–related adverse events, and all laboratory parameters remained in the normal range.
Conclusion: High-dose vitamin D was effective in increasing 25(OH)D levels in fully breastfeeding mothers to optimal levels without evidence of toxicity. Breast milk [Ca] and its decline in both groups during 1 to 4 months were independent of maternal vitamin D status and regimen. Both the mother and her infant attained improved vitamin D status and maintained normal [Ca].