To my knowledge, the Russians were the first to demonstrate that sunbeds reduced the incidence of respiratory infections. While I have not been able to find all the Russian studies, the several I did find were referenced in our two papers about influenza and vitamin D. I beg the readers pardon to brag a little bit. The first influenza paper our group published, Epidemic Influenza and Vitamin D, is the most cited review paper in the history of the journal Epidemiology and Infection.
Our second influenza paper, On the Epidemiology of Influenza, is the most viewed paper in the history of Virology Journal.
I wish I could say I can report today that scientists have produced lots of new evidence our theory is true, although a recent randomized controlled trial of 4,000 IU/day for a year showed vitamin D reduced colds by 25% and reduced antibiotic use by more than 60%.
What about sunbeds? Has anyone tried to reproduce the Russian’s work? Remember, the Russians used to use sunbeds year around, not just in the winter. That is important as it takes sunbeds several months to get vitamin D levels up to those needed to prevent infection.
Recently, Drs Frank de Gruijl and Stan Pavel of Leiden University Medical Center in the Netherlands administered a two month course of sunbed exposure, only to find the effect on infection during that two months was minimal.
They also found that 1,000 IU/day in the one third of their 105 young adults had no significant effect on respiratory infections for the two months they administered it, beginning in the middle of winter.
After two months of sunbed use, vitamin D levels rose from 23 ng/ml to 42 ng/ml. The sunbeds they used were effective in tanning the body, so they must have contained a lot of UVA, which is the wavelength that causes tanning but not much vitamin D production. The sunbeds only contained about 1.3% UVB. (Remember, you can get tan and still be vitamin D deficient as UVA wavelength tans you and mostly UVB wavelength triggers vitamin D production.)
The authors conclude,
“One could envisage that maintaining high levels of vitamin D immediately following the summer is most effective against colds, and that correcting a winter low in 25(OH)D while it is developing is not very effective – possibly because the immune system requires time (months?) to become adjusted to a certain vitamin D level.”
That is certainly what we first proposed, that for vitamin D to be effective, it must be given to a deficient population, in high enough doses (5,000 IU/day), for long enough (starting well before winter), so the immune system can begin making the antimicrobial peptides that protect our lungs from respiratory infections.