U.S. Department of Agriculture (USDA) and University of California, Davis (UC Davis) scientists have found that a higher dose of vitamin D supplement during pregnancy may reduce inflammation. Their findings were published in the November 2016 issue of The Journal of Nutrition.
The research team included Charles Stephensen, with the USDA-Agricultural Research Service (ARS) Western Human Nutrition Research Center (WHNRC) in Davis, California; Melissa Zerofsky, a former UC Davis doctorate student; and Bryon Jacoby, a maternal fetal medicine specialist affiliated with UC Davis Medical Center. Researchers wanted to find out whether vitamin D intake levels should be higher than those common in prenatal supplements—400 international units (IU).
Severe vitamin D deficiency can contribute to osteoporosis in adults and rickets (a condition of weakened bones) in infants and children. Recent surveys also suggest that vitamin D deficiency affects up to 69 percent of American pregnant women.
Higher vitamin D levels in a person's blood may protect against certain types of cancer, strengthen the immune system, reduce diabetes risk, and play a key role in suppressing inflammation. Reducing inflammation during pregnancy is important because inflammation is associated with high blood pressure, pre-eclampsia, premature delivery and low birthweight, according to Stephensen, research leader at WHNRC's Immunity and Disease Prevention Research Unit.
In the ARS-UC Davis study, healthy women in their first trimester of pregnancy voluntarily consumed different doses of vitamin D daily. They took either a multivitamin supplement containing 400 IU vitamin D and a placebo pill, or a 400 IU vitamin D supplement and an additional 1600 IU vitamin D pill. Blood samples were analyzed for various forms of vitamin D and immune and inflammatory markers. The mothers' blood pressure and infants' birthweight were recorded.
The vitamin D dosage did not affect maternal blood pressure or infant birthweight. However, the higher daily dose, 2000 IU vitamin D, increased circulating vitamin D concentrations relative to the 400 IU per day. Higher blood vitamin D was correlated with lower circulating tumor necrosis factor-α (TNF-α), an immune substance typically associated with inflammation.
The scientists concluded that consuming 2000 IU vitamin D instead of 400 IU each day is more effective at increasing vitamin D status in pregnant women. They also found that higher levels of vitamin D increased the proportion of a specific subset of immune cells with anti-inflammatory properties that may prevent adverse effects of excess inflammation.