Effects of Vitamin D Supplementation on Circulating Concentrations of Growth Factors and Immune-mediators in Healthy Women during Pregnancy

OBJECTIVE: For the second aim of the Kellogg Foundation grant, this double-blind RCT investigated the impact of plasma vitamin D metabolite, 25-hydroxyvitamin D (25(OH)D) on plasma immune-mediators during pregnancy. We hypothesized that higher 25(OH)D concentrations would associate with reduced pro-inflammatory and increased tolerogenic immune-mediator concentrations. METHOD: Pregnant women enrolled at 10–14 weeks gestation were randomized to 400 or 4400 IU vitamin D(3)/day. Data on health, safety, circulating 25(OH)D, and 9 immune-mediators were collected at each trimester. Associations between immune-mediators and 25(OH)D at baseline and at 2(nd) and 3(rd) trimesters were examined. RESULTS: Baseline TGF-β and 2(nd) and 3(rd) trimesters IFN-γ and IL-2 were associated with baseline 25(OH)D. Baseline immune-mediators were associated with immune-mediators at 2(nd) and 3(rd) trimesters for all immune-mediators except IL-5 and IL-10. Race was associated with baseline TGF-β, VEGF and IL-10 and with IL-10 at 2(nd) and 3(rd) trimesters. CONCLUSION: Both treatment groups had increased 25(OH)D at 2(nd) and 3(rd) trimesters, greatest in the 4400 IU group. Though associations between baseline 25(OH)D and baseline TGF-β and 2(nd) and 3(rd) trimester IFN-γ and IL-2 were noted, vitamin D supplementation throughout pregnancy did not impact immune-mediators at later trimesters. Supplementing with vitamin D before conception conceivably influences immune-mediator responses during pregnancy.