Re: Vitamin D supplementation to prevent acute respiratory tract infections: systematic review and meta-analysis of individual participant data
Rather than attacking the press for hyped, fashionably called "fake" news, as do several of the rapid responders, missed are the important issues raised in (1).
1. There is a highly significant benefit in respiratory tract infections in those with the lowest baseline level, <25nmol/L hydroxyvitamin D, which is a clear deficiency never found in those who regularly expose their skin to >45º above the horizon sun, an angle needed for the required UV-B to reach ground level, or in those regularly taking above minimal amounts of supplements.
2. The presence of such low common deficiency levels(2) alone is worthy of extensive press and medical world attention.
Regardless of a putative benefit in infections in some, all cell types have vitamin D receptors, indicating a system wide need that also includes bone health. Clearly we need more studies and I would propose one inspired by the cheapest and most creative ones ever by Trividi, Doll and Khaw(3), using the mail system and Freepost response cards. Supplied were 800 IU/d of D3 (as 100,000 IU 3x/year) and a 30% reduction of fractures of the "main osteoporotic sites" was found after 5 years, with other main events trending in the right direction. Unfortunately there was no question about respiratory illness.
For some perspective and while the experts debate, here in North America bottles with 1000 (25 mcg) or 2000 IU daily doses are on store shelves. However without that daily bother, 50,000 IU pills, a small bolus, taken in the order of monthly are available on-line at about $0.30 each, a consumer decision based on season and on personal risk, all over-the-counter thus indicating safety, as reported in (1).
1. A.R. Martineau et al. doi: https://doi.org/10.1136/bmj.i6583
2. 2. K.D. Cashman et al http://ajcn.nutrition.org/content/103/4/1033.long
3. Trivedi, Doll & Khaw. http://www.bmj.com/content/326/7387/469.long
Competing interests: No competing interests