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Vitamin D supplementation may be more effective than sun exposure at raising vitamin D levels

Posted on: December 20, 2017   by  Vitamin D Council


A recent study published by the Journal of Maternal, Fetal and Neonatal Medicine discovered that daily vitamin D supplementation was more effective than daily sun exposure in raising the vitamin D levels of pregnant women.

A total of 87 pregnant women with vitamin D levels less than 30 ng/ml were included in this 10-week clinical trial. Approximately half of the women were administered 4,000 IU of vitamin D3 daily. The other 44 women were recommended 30 minutes of daily sun exposure between the hours of 10AM and 4PM. The women were also recommended to expose at least 30% of their skin without the use of sunscreen. All the women were between 14-18 weeks pregnant, had type 2 or 3 skin types and worked indoor jobs.

This is what the researchers found:

  • At baseline, vitamin D levels were not significantly different between the two groups.
  • Vitamin D levels were significantly increased in both intervention groups (p < 0.001).
  • After 10 weeks, the supplementation group had significantly higher vitamin D levels compared to the sun exposure group (31.27 ng/ml versus 19.79 ng/ml; 78 nmol/l versus 49.5 nmol/l; p< 0.001).

The researchers concluded:

“We found that vitamin D supplementation is more effective than sun exposure in increasing 25-hydroxyvitamin D3 in pregnant women with vitamin D deficiency.”


Hajhashemi, M. et al. Comparison of sun exposure versus vitamin D supplementation for pregnant women with vitamin D deficiency. Journal of Maternal, Fetal and Neonatal Medicine, 2017.

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