Impact of vitamin D supplementation during lactation on vitamin D status and body composition of mother-infant pairs: a MAVID randomized controlled trial

Abstract

Objective: The optimal vitamin D intake for nursing women is controversial. Deterioration, at least in bone mass, is reported during lactation. This study evaluated whether vitamin D supplementation during lactation enhances the maternal and infant's vitamin D status, bone mass and body composition.

Design and methods: After term delivery, 174 healthy mothers were randomized to receive 1200 IU/d (800 IU/d+400 IU/d from multivitamins) or 400 IU/d (placebo+400 IU/d from multivitamins) of cholecalciferol for 6 months while breastfeeding. All infants received 400 IU/d of cholecalciferol. Serum 25-hydroxyvitamin D [25(OH)D], iPTH, calcium, urinary calcium, and densitometry were performed in mother-offspring pairs after delivery, and at 3 and 6 months later.

Results: A total of 137 (79%) (n = 70; 1200 IU/d, n = 67; 400 IU/d) completed the study. 25(OH)D was similar in both groups at baseline (13.7 ng/ml vs. 16.1 ng/ml; P = 0.09) and at 3 months (25.7 ng/ml vs. 24.5 ng/ml; P = 0.09), but appeared higher in the 1200 IU/d group at 6 months of supplementation (25.6 ng/ml vs. 23.1 ng/ml; P = 0.009). The prevalence of 25(OH)D <20 ng/ml was comparable between groups at baseline (71% vs. 64%, P = 0.36) but lower in the 1200 IU/d group after 3 months (9% vs. 25%, P = 0.009) and 6 months (14% vs. 30%, P = 0.03). Maternal and infants' iPTH, calciuria, bone mass and body composition as well as infants' 25(OH)D levels were not significantly different between groups during the study. Significant negative correlations were noted between maternal 25(OH)D and fat mass (R = -0.49, P = 0.00001), android fat mass (R = -0.53, P = 0.00001), and gynoid fat mass (R = -0.43, P = 0.00001) after 6 months of supplementation.

Conclusions: Vitamin D supplementation at a dose of 400 IU/d was not sufficient to maintain 25(OH)D >20 ng/ml in nursing women, while 1200 IU/d appeared more effective, but had no effect on breastfed offspring vitamin D status, or changes in the bone mass and the body composition observed in both during breastfeeding.

Trial registration: ClinicalTrials.gov NCT01506557.

Figure 1. Flow chart of the subjects across the study.

Figure 2. Maternal (A) and infants’ (B) vitamin D status.

Percentage of participants with serum 25(OH)D level <20 ng/ml, 20–29.9 ng/ml and >30 ng/ml in both study groups (maternal vitamin D intake 400 IU/d vs. 1200 IU/d). Significant (P<0.05) differences between the study groups are shown on the figures.

Figure 3. Maternal (A) and infants’ (B) serum 25(OH)D concentrations at baseline and during vitamin D supplementation in the study groups (maternal vitamin D dose: 400 IU/d vs. 1200 IU/d).

The effects of group (maternal vitamin D dose) × time interaction, group (maternal vitamin D dose) and time on maternal and infants’ serum 25(OH)D levels were obtained from a two-factor repeated-measures ANOVA. P-values for these effects among mothers are 0.00042, <0.000001, 0.25, and among infants 0.12, <0.000001, 0.45, respectively. P-values presented on the figures (A, B) were obtained from post-test analysis (Fisher’s LSD test) for differences in serum 25(OH) concentrations between the study groups and between the study visits. P-values<0.05 are significant. The study visits: V0- the baseline visit, V3, V6 – the visits after 3 and 6 months of vitamin D supplementation.

Figure 4. Maternal (A, B) and infants’ (C) % change (between baseline and 6 months visit) in body composition and anthropometric parameters in the study groups during vitamin D3 supplementation.

No significant difference between the study groups for all variables (P-values>0.05). BMD - bone mineral density, less head BMD - total body less head mineral density, BMC -bone mineral content, less head BMC - total body less head mineral content, LBM - total lean body mass, BMI - body mass index, FM - total fat, android FM – android fat mass, gynoid FM – gynoid fat mass.