Vitamin D is one of the most common nutrient deficiencies in the US and around the world. It can be challenging to get adequate Vitamin D from the diet, and not everyone produces enough Vitamin D in their skin to make up for this gap. A new study published in the Journal of Nutrition looked at pregnancy, nutrition, and Vitamin D.
“Nutrition during pregnancy can have important consequences for a baby’s development,” study author Melissa Melough told us. “Vitamin D is one key nutrient involved in a baby’s brain development, so we wanted to investigate whether vitamin D levels during pregnancy were related to children’s IQ scores.”
According to the World Health Organization, proper nutrition in pregnancy helps with weight control, anemia, and lowers the risk of preterm delivery. The WHO recommends pregnant women consume a variety of foods to meet their nutritional requirements including orange and green vegetables, fruit, beans, nuts, fish, meat, and pasteurized dairy.
Researchers theorized that low Vitamin D levels during pregnancy would be harmful to children’s brain development and would result in lower IQ scores during childhood.
It’s estimated that 80% of pregnant Black women and 13% of pregnant white women in the US are deficient in Vitamin D. Those with darker skin are at greater risk of deficiency because melanin pigment blocks UV light, which is necessary for production of Vitamin D in the skin.
“Because Vitamin D deficiency is such a common problem, and because Vitamin D plays an important role in brain development,” Melough told us, “we felt it was critical to investigate this topic.”
Researchers conducted an analysis using data from a large cohort study based in Tennessee called CANDLE (Conditions Affecting Neurocognitive Development and Learning in Early Childhood). This study began recruiting pregnant women in 2006, and continues to gather health-related information from mothers and their children over time. They examined the relationship between mothers’ Vitamin D levels in the second trimester of pregnancy and children’s IQ scores measured between the ages of four and six years. They also took into account other factors that might be related to Vitamin D status or IQ.
“We found that nearly half of the mothers in this study were deficient in Vitamin D during their pregnancy,” Melough told us. “After we controlled for other important factors, we saw that higher Vitamin D levels in pregnancy were associated with higher IQ scores in childhood.”
Researchers had previously found in CANDLE that higher vitamin D levels in pregnancy were associated with greater language development scores in children at age two years.
“The results of this study suggest that Vitamin D deficiencies in pregnancy can have even longer lasting consequences for children’s neurocognitive development than we previously knew,” Melough told us. “This study highlighted the fact that Vitamin D deficiency in pregnancy is a common problem, and showed that it may contribute to lower IQ scores in children.”
Most people have a hard time getting enough Vitamin D from their diets because relatively few foods are rich in Vitamin D. Major sources include fatty fish, mushrooms, and fortified milk and breakfast cereals. Sun exposure is not always a reliable method for filling in this nutrient gap, especially for women with dark skin or those who wear sunscreen or protective clothing outdoors.
“Therefore, supplementation may be necessary for many women to reach adequate Vitamin D status in their pregnancy,” Melough told us. “Healthcare providers should be looking out for women at high risk of Vitamin D deficiency and recommending appropriate nutritional supplementation. Improved screening and treatment of Vitamin D deficiency may be a relatively simple and powerful strategy for reducing an important health disparity.”