Vitamin D supplements may reduce childhood influenza A risk
MedWire News: Vitamin D supplementation may reduce the risk for seasonal influenza A infection and asthma attacks in children, study results suggest.
The findings, published in the American Journal of Clinical Nutrition, follow those from another study, recently reported by MedWire News, showing a relationship between low levels of vitamin D and increased severity of respiratory symptoms in patients with asthma.
In the current study, Mitsuyoshi Urashima (Jikei University School of Medicine, Tokyo, Japan) and colleagues studied 334 children, aged 6–15 years, who were randomly assigned to take daily vitamin D3 supplements (n=167) or placebo (n=167) in the winter of 2008/2009.
The primary outcome was the incidence of influenza A, which was diagnosed with influenza antigen testing of nasopharyngeal swab specimens, over the 4-month study period.
The researchers found that 31 (18.6%) children assigned to placebo developed influenza A compared with just 18 (10.8%) of those assigned to take vitamin D3 supplements. Indeed, the relative risk (RR) for influenza A infection was 42% lower in children taking vitamin D3 supplements than in those taking placebo.
The reduced risk for influenza A associated with vitamin D3 supplementation was even lower for children who had not been taking other vitamin D supplements (RR=0.36) and those who started nursery school after the age of 3 years (RR=0.36).
The investigators also observed that vitamin D3 supplementation was associated with an 83% reduced relative risk for asthma attacks in children with the respiratory condition.
Urashima and team conclude: “This study suggests that vitamin D3 supplementation during the winter may reduce the incidence of influenza A, especially in specific subgroups of schoolchildren.”
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By Mark Cowen