Much more than you wanted to know about COVID and Vitamin D

Wednesday, February 17th, 2021

Scott Alexander shares his beliefs after doing the research on COVID and Vitamin D:

Does Vitamin D significantly decrease the risk of getting COVID?: 25% chance this is true. The Biobank and Mendelian randomization studies are strong arguments against this; the latitude, seasonal, and racial differences are only weak evidence in favor.

Does Vitamin D use at a hospital significantly improve your chances?: 25% chance this is true. I trust the large Brazilian study more than the smaller Spanish one, but aside from size and a general bias towards skepticism I can’t justify this very well.

Do the benefits of taking a Vitamin D supplement at a normal dose equal or outweigh the costs for most people?: 75% chance this is true. The risks are pretty low, and it will probably bring you closer to rather than further from a natural range if you’re a modern indoor worker (side effects are few; the most serious is probably kidney stones, so don’t take it if you have any tendency towards that). And maybe some day, after countless false leads and stupid red herrings, one of the claims people make about this substance will actually pan out. Who knows?


  1. Kirk says:

    Well worth a read…

    The author actually “gets” the scientific method, which is amazing in this day and age.

  2. Dan Kurt says:

    Scott Alexander is a psychiatrist, not a practicing physician, so consider the source.

    Watch this video on Vitamin D and COVID 19:

  3. Wang Wei Lin says:

    Dan, The source is irrelevant if the empirical data is sifted through the scientific method. Most of the soft science fields are solid on their statistics.

  4. Kirk says:

    Recommend that you read the whole thing, and follow all the links…

    Social “Science” is generally… Not science. Not as anyone with more than a smattering of exposure to the classical “scientific method” would recognize it.

    You go and actually read even the summaries of a lot of what these “newsworthy science” reports, and what you’re going to find is that the “journalist” demonstrates a strong likelihood that they did not read the underlying work, and if they did, they did not understand it. The vast majority lack the actual numeracy to even grasp the outlines of the math involved, and are only able to parrot whatever they misunderstand from the press conference. Which rarely actually reflects the actual studies…

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