Last year, I got a respiratory tract infection (RTI) that lasted 10 days and was quite severe. It took me by complete surprise. I couldn’t remember the last time I had a RTI. I was taking 10,000 IU/day of vitamin D, a dose I had been on for over ten years. Then, I remembered that I’d only hypothesized that vitamin D would reduce, not eliminate, RTI.
In 2006, our group was the first to hypothesize this theory in a paper that is, I am proud to say, the most cited review paper in the history of the journal.
In that paper, besides hypothesizing that vitamin D would reduce the risk of developing a RTI, we wrote,
“If the ability of vitamin D to stimulate the production of virucidal antimicrobial peptides and to suppress cytokine and chemokine production is clinically significant, then pharmacological doses (1000– 2000 IU/kg per day for several days) may be useful in the treatment of those viral respiratory infections that peak in wintertime.”
To my knowledge, that thesis has never been tested, probably because no researcher is willing to use that high of a dose (for me, at about 100 kg that would be 100,000 to 200,00IU/day for several days).
The World Health Organization reports on one type of RTI, influenza:
“Every winter, tens of millions of people get the flu. Most are only ill and out of work for a week, yet the elderly are at a higher risk of death from the illness. We know the worldwide death toll exceeds a few hundred thousand people a year, but even in developed countries the numbers are uncertain, because medical authorities don’t usually verify who actually died of influenza and who died of a flu-like illness.”
As far as prevention goes, recently researchers at the Karolinska Institute and Karolinska University Hospital in Sweden, led by Doctor Peter Bergman, reanalyzed the data from a previously conducted randomized controlled trial.
Bergman P, Norlin AC, Hansen S, Björkhem-Bergman L. Vitamin D supplementation to patients with frequent respiratory tract infections: a post hoc analysis of a randomized and placebo-controlled trial. BMC Res Notes. 2015 Aug 30;8(1):391. doi: 10.1186/s13104-015-1378-3.
In that trial, they randomized 124 subjects prone to upper respiratory infections (URI) to either 4,000 IU/day or placebo for one year, and they found significant vitamin D effects. Now, they took their data and reanalyzed it to find subjects on vitamin D (n = 62) increased the probability to stay free of RTI during the study year (RR 0.64). Furthermore, the total number of RTIs was also reduced in the vitamin D-group (86 RTI) versus placebo (120 RTIs; p = 0.05).
Finally, the time to the incidence of the first RTI was significantly extended in the vitamin D-group (HR 1.68, p = 0.0376). They also noticed that the beneficial effects of vitamin D took 120 days to show themselves, exactly what you would expect when no initial bolus dosing is used.
The authors concluded,
“In this post hoc analysis of a randomized clinical trial vitamin D supplementation was found to significantly increase the probability of staying infection free during the study period. This finding further supports the notion that vitamin D-status should be monitored in patients with frequent RTIs and that selected patients with vitamin D-deficiency are supplemented. This could be a safe and cheap way to reduce RTIs and improve health in this vulnerable patient population.”
I wonder what effects they would have found if they initially gave a bolus of 50,000 IU/day for seven days followed by 10,000 IU/day for a year?
With an average death toll of about 200,000 people a year from influenza alone, I wonder who will be the first to test our theory that pharmacological doses of vitamin D (2,000 IU/kg/day or 50,000 to 200,000 IU/day depending on body weight for seven days) reduces the signs and symptoms of RTI?