A recent experiment published in JAMA, one of the most prestigious medical journals in the world, found that giving people a very large dose of Vitamin D (100,000 IU) once/month did not prevent colds, even though it greatly increased blood levels of Vitamin D. This finding supports my view that it is important to take Vitamin D in the morning. (Because a study in which this wasn’t done found no effect.) My view implies that blood levels may not matter — you can get high levels of Vitamin D by taking it at what I consider the wrong times of day. The usual thinking about Vitamin D has been that blood level is all that matters.
The editors of JAMA considered the Vitamin D study so important that they asked someone (Dr. Jeffrey Linder, associated with Harvard Medical School) to write a commentary — an associated editorial that puts the new finding in context.
Linder’s commentary (might be gated) is important because (a) it is a kind of random sample of how top research doctors think (he was selected to write it) and (b) he completely fails to grasp that the time of day Vitamin D is taken might matter. Colds, the immune system, sleep, time of day — it’s not far-fetched. When you do an experiment to see if X causes Y, and find no effect, I believe that there are usually many possible reasons other than X never causes Y. Something was wrong with the equipment, something was wrong with your X (e.g., it was stale), something was wrong with your measurements (e.g., ceiling effect), and on and on. Linder did not see it this way.
The 2011 IOM report called for additional research to determine whether vitamin D therapy reduces the incidence of respiratory tract infections. The VIDARIS trial [= the new study] has rigorously addressed this question. Results suggest that vitamin D should join the therapies listed in the Cochrane reviewsas being ineffective for preventing or treating upper respiratory tract infections in healthy adults.
He seriously thinks one null result proves something. Sure, the new study is “rigorous” in certain ways. But it was far from exhaustive. It did not explore the many ways Vitamin D may be given, for example. It did not consider the possibility that blood levels don’t matter. Linder’s combination of (a) interest in rigor and (b) failure to understand the importance of exhaustive reminds me of a friend. When she was in 1st grade she had a pile of pennies. She knew how many she had — she had counted them. However, she did not know how to subtract. When she spent some of her pennies, to find out how many she had left she had to count them all over again.
My friend had half the skills an accountant needs. Linder’s commentary reflects only half the skills a scientist needs. To the extent that he is representative of top research doctors, this is shocking. It is as if most accountants at Arthur Andersen didn’t know how to subtract.
I have asked Dr. Linder if he has any response. If he does, I will post it.