More evidence to give your children vitamin D to prevent flu

You're probably aware of the profound importance of vitamin D for immune system regulation, and some of the earlier science that supports its use to prevent opportunistic infections. Now research just published in the American Journal of Nutrition adds more evidence for the use of vitamin D supplementation to prevent flu in kids attending school.

"From December 2008 through March 2009, we conducted a randomized, double-blind, placebo-controlled trial comparing vitamin D3 supplements (1200 IU/d) with placebo in schoolchildren. The primary outcome was the incidence of influenza A, diagnosed with influenza antigen testing with a nasopharyngeal swab specimen."

The data showed that while 18.6% of the children in the placebo group came down with influenza A, only 10.8% in the vitamin D3 group did. Naturally...

"The reduction in influenza A was more prominent in children who had not been taking other vitamin D supplements..."

Their data yielded another interesting finding:

"In children with a previous diagnosis of asthma, asthma attacks as a secondary outcome occurred in 2 children receiving vitamin D3 compared with 12 children receiving placebo."

That's an 83% reduction in the relative risk of having an asthma attack. This is biologically plausible considering the importance of vitamin D for immune inflammatory disorders. The authors conclude by stating:

"This study suggests that vitamin D3 supplementation during the winter may reduce the incidence of influenza A, especially in specific subgroups of schoolchildren."

Bear in mind, however, that individual needs vary greatly. The best way to objectively know that your child's vitamin D needs are being met (or your own) is with a blood test for 25-hydroxy vitamin D.