by Chris Masterjohn
Well, technically we only "prove" things in math and logic, when we assume our premises. But the most recent study on vitamin D and the flu, published in the American Journal of Clinical Nutrition, gets as close to proving anything as we can get in nutritional and medical science.
Researchers from Japan conducted a double-blind, randomized, placebo-controlled trial involving over 300 school children aged 6 to 15 years old. Eight physicians were involved in diagnosing the flu among these children, spread across 12 hospitals. They randomly allocated half the chilren to take 1200 IU per day of vitamin D and the other half to take a placebo. The children took the supplements from the beginning of December, 2008 to the end of March, 2009.
Barely over ten percent of children in the vitamin D group developed Influenza A, whereas almost twenty percent developed the illness among the placebo group. This suggests that vitamin D cut the risk of developing the flu almost in half. Many of the children in both groups began taking additional vitamin D supplements after the trial was underway, however. Excluding these children from the analysis showed that vitamin D cut the risk of flu by 64 percent, or just under 2/3.
In a remarkable secondary finding, vitamin D appeared to nearly obliterate the risk of asthma attacks. Children who were previously diagnosed with asthma were six time more likely to have an asthma attack during the course of the study if they were in the placebo group. This suggests that vitamin D supplementation reduced the risk of getting an asthma attack by 83 percent.
The authors cited previous work showing that the drugs marketed as Relenza and Tamiflu only reduce the incidence of flu by eight percent. While comparing across studies is never as reliable as a study designed to compare two treatments, we can tentatively consider from this comparison that vitamin D is eight times more effective than Relenza or Tamiflu.
Vitamin D directly interacts with our DNA and tells our genes to start making more flu-killing "antimicrobial peptides." One of these, named "defensin," stops the flu virus from invading cell membranes.
The authors of the paper also cited other studies showing that probiotics (good bacteria) and a preparation of echinacea, propolis, and vitamin C helped reduce the risk of flu.
Why take shots and drugs when good nutrition gives us the immunity to illness we're supposed to have?
Read more about the author, Chris Masterjohn, PhD, here.