Effects of Maternal Vitamin D Supplementation on the Maternal and Infant Epigenome

Abstract

Introduction: Mothers and infants are at high risk for inadequate vitamin D status. Mechanisms by which vitamin D may affect maternal and infant DNA methylation are poorly understood.

Objective: This study quantified the effects of vitamin D₃ supplementation on DNA methylation in pregnant and lactating women and their breastfed infants.

Materials and methods: In this randomized controlled pilot study, pregnant women received vitamin D₃ 400 international units (IU) (n = 6; control) or 3,800 IU (n = 7; intervention) daily from late second trimester through 4-6 weeks postpartum. Epigenome-wide DNA methylation was quantified in leukocytes collected from mothers at birth and mother-infant dyads at 4-6 weeks postpartum.

Results: At birth, intervention group mothers showed DNA methylation gain and loss at 76 and 89 cytosine-guanine (CpG) dinucleotides, respectively, compared to controls. Postpartum, methylation gain was noted at 200 and loss at 102 CpGs. Associated gene clusters showed strongest biologic relevance for cell migration/motility and cellular membrane function at birth and cadherin signaling and immune function at postpartum. Breastfed 4-6-week-old infants of intervention mothers showed DNA methylation gain and loss in 217 and 213 CpGs, respectively, compared to controls. Genes showing differential methylation mapped most strongly to collagen metabolic processes and regulation of apoptosis.

Conclusions: Maternal vitamin D supplementation during pregnancy and lactation alters DNA methylation in mothers and breastfed infants. Additional work is needed to fully elucidate the short- and long-term biologic effects of vitamin D supplementation at varying doses, which could hold important implications for establishing clinical recommendations for prenatal and offspring health promotion.

Keywords: DNA methylation; breastfeeding; epigenomics; infant; lactation; pregnancy.

FIG. 1.

CONSORT diagram for enrollment, allocation, follow-up, and analysis. Reproduced in edited form with permission from Thiele et al.

FIG. 2.

Heat map showing cytosine-guanine (CpG) dinucleotides with differential methylation. Leukocyte CpG dinucleotides with a significant gain or loss of methylation (delta.beta >0.2 or <−0.2, respectively; p < 0.05) among the intervention versus control group, with women in the intervention group receiving daily prenatal vitamins containing 400 international units (IU) vitamin D₃ plus a vitamin D capsule containing 3,400 IU and women in the control group receiving daily prenatal vitamins containing 400 IU vitamin D₃ plus a placebo capsule. Data displayed compare DNA methylation quantified using the Illumina Infinium 450K array, with genomic DNA templates isolated from: (a) maternal leukocytes at time of birth, (b) maternal leukocytes at 4–6 weeks postpartum, and (c) infant leukocytes at 4–6 weeks of life. For each heat map, samples are displayed on the horizontal axis (control group: green, intervention group: orange), while differentially methylated CpG is displayed on the vertical axis. Methylation is displayed as a beta score ranging from 0 (unmethylated: blue) to 1 (fully methylated: red). CpG is classified based on their relation to cataloged CpG islands with a colored bar on the vertical axis (CpG island: red, shelf regions: light blue, shore regions: purple, open sea: dark blue).