Benefits of extra vitamin D during pregnancy

By Wayne Persky

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It's well known, and verified by published research, that vitamin D deficiency during pregnancy can be associated with adverse outcomes, such as preterm birth, gestational diabetes, and low birth weight. So it doesn't take much of a stretch of the imagination to rationalize that vitamin D supplementation during pregnancy might provide benefits. And indeed, even the new guidelines of the Endocrine Society recommend that pregnant people should take supplemental vitamin D above the recommended intake levels of the Institutes of Medicine (IOM), because of the potential to reduce the risk of pre-eclampsia, intra-uterine mortality, preterm birth, small-for-gestational age birth, and neonatal mortality (Press release, 2024, June 03).1

Most recent vitamin D research has resulted in disappointing findings.

As a result, many of us have doubted the accuracy of the findings that have been published regarding most of the recently published research articles, because they invariably claim to find that taking supplemental vitamin D provides no benefits. So it was rather surprising to see that some British researchers have recently published the results of a study that showed that taking additional vitamin D during pregnancy provides significant benefits above and beyond those suggested by the IOM (Moon, et al., 2024).2

The benefits for their offspring were impressive.

Unlike most vitamin D studies, this study by researchers at the University of Southampton, took a different approach for studying benefits of vitamin D supplementation. They found that children whose mothers took daily vitamin D supplements during pregnancy had stronger bones, with higher bone mineral density.

And the benefits are lasting.

In the study, assessments made at age four showed improved bone health in these children. And follow-up assessments made at age seven also showed significant improvements in bone health. This implies that vitamin D supplementation contributes to a lasting increase in calcium and mineral content in bones, reinforcing the value of maternal vitamin D as a preventative measure against future bone health issues, including osteoporosis.

Are epigenetics involved?

This suggests that epigenetic mechanisms may also be involved in the impact of vitamin D supplementation on bone outcomes later in childhood, although this has not yet been verified by research. In other words, although vitamin D supplementation by their mothers during gestation cannot change their genetics, it may change the way certain genes are expressed during their developmental years. Consider that the vitamin D receptor (VDR) is a nuclear, ligand-dependent transcription factor. When activated by the active form of vitamin D (1,25[OH]2D3), it regulates the expression of more than 900 genes in the body that play a role in a huge variety of chemical and physiological functions.

This adds robust support for vitamin D supplements for pregnant women.

The results of this study add weight to those guidelines by verifying how supplemental vitamin D during pregnancy reduces the risk of bone-related health issues for newborns and developing children later in life, such as fractures and osteoporosis, this approach could contribute to reducing healthcare costs associated with bone health.

And the study found additional benefits.

Beyond bone health, earlier findings from the trial indicated that vitamin D supplementation during pregnancy may reduce the likelihood of atopic conditions like eczema in infants up to a year old, showing vitamin D's potential to impact immune health. And the trial also verified that mothers receiving supplemental vitamin D were more likely to have spontaneous vaginal deliveries, potentially reducing the need for medical interventions during childbirth.

References

1. Press release. (2024, June 03). Endocrine Society Guideline recommends healthy adults under the age of 75 take the recommended daily allowance of vitamin D. Endocrine Society, Retrieved from https://www.endocrine.org/news-and-advocacy/news-room/2024/endocrine-society-recommends-healthy-adults-take-the-recommended-daily-allowance-of-vitamin-d

2. Moon, R. J., D’ Angelo, S., Curtis, E. M., Ward, K. A., Crozier, S. R., Schoenmakers, I., . . . Prentice, A. (2024). Pregnancy vitamin D supplementation and offspring bone mineral density in childhood follow-up of a randomized controlled trial. The American Journal of Clinical Nutrition, 120(5), 1134. Retrieved from https://pubmed.ncbi.nlm.nih.gov/39306330/