Topical Area: Vitamins and Minerals
Objectives : To estimate the dose-response effect of 4,200 IU/week, 16,800 IU/week and 28,000 IU/week of vitamin D3 during pregnancy (versus placebo) on maternal delivery whole blood (maternal) and venous cord blood (cord) concentrations of the toxic metals lead (Pb), cadmium (Cd), mercury (Hg), and manganese (Mn) in a randomized clinical trial in Bangladesh.
The study included a sub-set of participants (maternal: n=619; cord: n=516) from the Maternal Vitamin D for Infant Growth (MDIG) randomized controlled trial in Dhaka, Bangladesh. Vitamin D3 or placebo was administered from 17-24 weeks gestation until delivery. Metal concentrations (maternal and cord) were quantified using inductively coupled plasma mass spectrometry. Metal concentrations in each treatment group were compared to placebo using linear regression. Maternal Cd and Hg and all cord metals were log-transformed due to non-normal distributions, and results were expressed as percent differences.
Compared to placebo, cord Pb was 8.5% higher in the 4,200 IU/week group (CI: -3.6%, 22%; p=0.18), 16% higher in the 16,800 IU/week group (CI: 3.2%, 30%; p=0.01) and 11% higher in the 28,000 IU/week group (CI: 0.36%, 23%; p=0.04). Since 76% of cord Cd samples were below the limit of detection, we dichotomized Cd as detectable or non-detectable. The risk of having detectable Cd was 2.18-fold higher in the 4,200 IU/week group (CI:1.27, 3.75; p=0.005), 1.38-fold higher in the 16,800 IU/week group (CI: 0.76, 2.50; p=0.29), and 1.72-fold higher in the 28,000 IU/week group (CI:1.02, 2.91; p=0.04). Prenatal vitamin D3 did not affect maternal metal concentrations, or cord Hg or Mn concentrations.
Conclusions : Vitamin D3 increased cord Pb and Cd concentrations without clear dose-response effects. Even at high intake levels, vitamin D3 supplementation in pregnancy was not associated with other cord metal or maternal metal concentrations. Further longitudinal studies are required to explore how vitamin D treatment increases cord metal levels, with little or transient effect on maternal levels, and to describe the trajectory of metal concentrations across gestation in response to vitamin D supplementation.
Funding Sources :
Bill and Melinda Gates Foundation.
The Hospital for Sick Children, Canada & University of Toronto, Canada
Hospital for Sick Children, Canada & University of Toronto, Canada
Hospital for Sick Children, Canada
Abdullah Al Mahmud
International Centre For Diarrhoeal Disease Research, Bangladesh
Anne Marie Jukic
National Institute of Environmental Health Sciences