Race matters with vitamin D and anemia

Although vitamin D insufficiency is associated with anemia in healthy US children, threshold levels vary with race, a new study finds.

Researchers at the Johns Hopkins Children Center, Baltimore, Maryland, conducted a cross-sectional study of over 10,000 children and adolescents aged between 1 and 21 years who participated in the 2001-2006 National Health and Nutrition Examination Survey.

They found that children with levels of vitamin D at less than 30 ng/mL were at almost twice the risk for anemia as those with normal vitamin D levels, and those children with levels of vitamin D at less than 20 ng/ml were at about 50% increased risk.

Perhaps more interestingly, the investigators found that black children have higher rates of anemia than white children (14% vs 2%, respectively) and have considerably lower vitamin D levels overall, but their risk for anemia does not rise until their vitamin D levels drop far lower than those of white children.

The investigators say the findings suggest that thresholds for supplementation may need to be revisited.

Anemia affects about 1 in every 5 children at some point during their journey to adulthood, according to Johns Hopkins.

The researchers were careful to explain that although a strong association exists between vitamin D and anemia, their findings do not show a causal link. They are also not certain of the mechanism by which vitamin D affects hemoglobin and the development of anemia.

The study was funded by the National Institute of Diabetes and Digestive and Kidney Diseases. 

To get weekly clinical advice for today's pediatrician, subscribe to the Contemporary Pediatrics eConsult.