Children with low levels of vitamin D may be at increased risk for anaemia, according to a large new study.
Researchers analysed blood samples from more than 10 400 children and found that vitamin D levels were consistently lower in youngsters with anaemia, a condition involving lower-than-normal levels of red blood cells.
Kids with vitamin D levels below 30 nanograms per millilitre (ng/ml) were nearly twice as likely to have anaemia as those with normal vitamin D levels.
Children with vitamin D
levels below 30 ng/ml have mild vitamin D deficiency while those with levels at
or below 20 ng/ml have severe deficiency, according to the study. Both require
treatment with vitamin D supplements.
Pathologically low
The researchers also found that 14% of black children had anaemia, much higher than the 2% rate among white children. Black children also had lower vitamin D levels overall, but their anaemia risk did not rise until their vitamin D levels were far lower than those of white children.
These racial differences suggest that current targets for preventing or treating these conditions may require further research, according to the authors of the study, which was published online in the Journal of Paediatrics.
"The clear racial variance we saw in our study should serve as a reminder that what we may consider a pathologically low level in some may be perfectly adequate in others, which raises some interesting questions about our current one-size-fits-all approach to treatment and supplementation," said study lead investigator Dr Meredith Atkinson, a paediatric kidney specialist at the Johns Hopkins Children's Centre.
Risk factor
The study does not, however, prove a direct cause-and-effect link between vitamin D levels and anaemia risk, the researchers said.
Dr Jeffrey Fadrowski, also a paediatric kidney specialist at Johns Hopkins, said: "If our findings are confirmed through further research, low vitamin D levels may turn out to be a readily modifiable risk factor for anaemia that we can easily tackle with supplements."
The researchers explained that several mechanisms could account for this association, including vitamin D's effects on red blood cell production in the bone marrow or its ability to regulate immune inflammation, a known trigger of anaemia.
More information
The Nemours Foundation has more about anaemia in children.