Lead investigator Dr. Meredith Atkinson, a pediatric nephrologist at The Johns Hopkins Children's Center, and colleagues examined the relationship between hemoglobin -- how anemia is measured -- and vitamin D, by looking at data from the blood samples of more than 9,400 children, ages 2-18.
The study found the lower the vitamin D levels, the lower the hemoglobin -- the number of oxygen-carrying red blood cells -- and the higher the risk for anemia.
Children with levels below 20 nanograms per milliliter of blood had a 50 percent higher risk for anemia than children with levels 20 ng/ml and above. For each 1 ng/ml increase in vitamin D, anemia risk dropped by 3 percent, the researchers say.
In addition, the findings, presented at the annual meeting of the Pediatric Academic Societies in Denver, indicated only 1 percent of white children had anemia, compared with 9 percent of black children. Researchers have long known that anemia is more common among black children but the reasons remain unclear. The study suggests low vitamin D levels in black children may be an important contributor to anemia.
"The striking difference between black and white children in vitamin D levels and hemoglobin gives us an interesting clue that definitely calls for a further study," Atkinson says in a statement.