An insufficient supply of vitamin D may increase the risk of anemia in children

A new US study reports that low blood vitamin D levels seem to increase the risk of red blood cell deficiency in healthy children.

In the observational study, the concentrations of vitamin D and hemoglobin were measured in the blood samples of 10,410 apparently healthy children and adolescents, aged 1 to 21 years (1). The study results showed that vitamin D levels were consistently lower in children with low hemoglobin levels compared with non-anemic children. Children with mild vitamin D deficiency (levels below 30 nanograms per milliliter) had nearly twice the risk of anemia compared with those who had normal vitamin D levels. Black children had higher rates of anemia compared with white children (14% vs. 2%) and had considerably lower vitamin D levels overall, but their risk of anemia did not increase until their vitamin D levels dropped far lower than those of white children.

The researchers commented that these results are not proof of cause and effect, but rather evidence of a complex interplay between low vitamin D levels and hemoglobin (the oxygen-binding protein in red blood cells). If the findings are confirmed through further research, low vitamin D levels may turn out to be a readily modifiable risk factor for anemia that can be easily treated with supplements. The racial variance seen in the study shows that a pathologically low vitamin D level in some may appear to be adequate in others. This would raise questions about the current one-size-fits-all approach to treatment and supple- mentation.

Anemia, which occurs when the body does not have enough oxygen-carrying red blood cells, is believed to affect one in five children at some point in their lives. Several large scale studies have found severe vitamin D deficiency (at or below 20 ng/ml) in about one-tenth of US children, while nearly 70% have suboptimal levels. Untreated chronic anemia and vitamin D deficiency can have wide-ranging health consequences, including organ damage, skeletal deformities and frequent fractures, and lead to premature osteoporosis in later life. Several mechanisms could account for the link between vitamin D and anemia, including vitamin D's effects on red blood cell production in bone marrow, as well as its ability to regulate immune inflam- mation, a known catalyst of anemia.

1. Atkinson M. A. et al. Vitamin D, race, and risk for anemia in children. The Journal of Pediatrics. Published online October 2013.