Are greater vitamin D levels during pregnancy linked with higher child IQ? Study suggests it may be likely
Vitamin D is a key nutrient and has many important functions in the body. A mother’s vitamin D supply is passed to her baby in utero and helps regulate processes, including brain development. A research team has now found that a mother’s vitamin D levels during pregnancy are associated with their children’s IQ, suggesting that higher vitamin D levels in pregnancy may lead to greater childhood IQ scores.
After controlling for several other factors related to IQ, higher vitamin D levels in pregnancy were associated with higher IQ in children ages 4 to 6 years old. The authors explain that higher vitamin D levels among mothers during pregnancy may promote brain development and lead to higher childhood IQ scores. While observational studies like this one cannot prove causation, they believe the findings have important implications and warrant further research.
“In conclusion, gestational vitamin D concentrations were positively associated with IQ at age 4-6 years, suggesting that vitamin D plays an important role in programming neurocognitive development. Vitamin D status may, therefore, be an important modifiable factor during pregnancy that can be optimized through appropriate nutritional recommendations and guidance,” write authors. The team includes experts from Seattle Children’s Research Institute; University of Tennessee Health Science Center; University of California San Francisco; and the University of Washington. “Future studies examining vitamin D status throughout pregnancy should be conducted to elucidate potential critical windows during gestation,” they recommend.
The investigators used data from a cohort in Tennessee called the Conditions Affecting Neurocognitive Development and Learning in Early Childhood (CANDLE) study. CANDLE researchers recruited pregnant women to join the study starting in 2006 and collected information over time about their children’s health and development.
Black women at greater risk of vitamin D deficiency
Vitamin D deficiency is a worldwide problem affecting the general public and women of childbearing age, especially among those with darker skin because melanin pigment in the skin reduces the production of vitamin D. The current analysis, published in the Journal of Nutrition, also identified significantly lower levels of vitamin D levels among Black pregnant women.
“I want people to know that it’s a common problem and can affect children’s development. Vitamin D deficiency can occur even if you eat a healthy diet. Sometimes it’s related to our lifestyles, skin pigmentation or other factors outside of our control,” writes Melissa Melough, the lead author of the study and research scientist in the Department of Child Health, Behavior, and Development at Seattle Children’s Research Institute. The recommended daily intake of vitamin D is 600 international units (IU). On average, Americans consume less than 200 IU in their diet. So if people are not making up that gap through sun exposure or supplementation, experts say people will probably become deficient.
According to the analysis, as many as 80% of Black pregnant women in the US may be deficient in vitamin D. Of the women who participated in the study, approximately 46% of the mothers were deficient in vitamin D during their pregnancy, and vitamin D levels were lower among Black women compared to White women.
Melough hopes that the report will help healthcare providers address disparities among women of color and those who are at higher risk for vitamin D deficiency. “Melanin pigment protects the skin against sun damage, but by blocking UV rays, melanin also reduces vitamin D production in the skin. Because of this, we weren’t surprised to see high rates of vitamin D deficiency among Black pregnant women in our study. Even though many pregnant women take a prenatal vitamin, this may not correct an existing vitamin D deficiency,” explains Melough. She adds, “I hope our work brings greater awareness to this problem, shows the long-lasting implications of prenatal vitamin D for the child and their neurocognitive development, and highlights that there are certain groups providers should be paying closer attention to.”
Melough suggests that additional studies are needed to determine the optimal levels of vitamin D in pregnancy, but hopes that their report will help to develop nutritional recommendations for pregnant women. She adds that while widespread testing of vitamin D levels is not generally recommended, healthcare providers should be looking out for those who are at higher risk, including Black women. “Screening and nutritional supplementation may correct vitamin D deficiency for those at high risk and promote cognitive function in offspring. Especially among Black women and those at high risk for vitamin D deficiency, nutritional supplementation and screening may be an impactful strategy for reducing health disparities,” the team emphasizes.