> Many of the people supplementing are doing it because they believe it will keep them healthy - and this does not appear to be the case. I agree with much of

> Many of the people supplementing are doing it because they believe it will keep them healthy - and this does not appear to be the case. I agree with much of your thinking - just not this particular conclusion. 1. As you mention, we know that low-to-moderate levels of vitamin D supplementation is safe. 2. We also know that a solid chunk of the population does not get enough sunlight / is vitamin D insufficient. 3. There are no large-scale trials yet for some items where vitamin D is suspected to have good effects. But there are a few nevertheless, which you share within the article itself - cancer, mortality, respiratory disease particularly stand out. 4. There are also a pile of smaller but promising, statistically significant, double-blinded, randomised controlled trials in a bunch of useful areas. 5. So this seems to be a Pascal's Wager type of situation, where supplementation is all upside and no downside, as long as people don't get crazy with it. As you say it's not a panacea, and to cite an old comment, I am aware [1] that there are other benefits you get from sunlight. But even if it doesn't do as much as people think, I don't see why it is bad advice for most people to supplement vitamin D to keep themselves healthy! [1] https://news.ycombinator.com/item?id=19247337 https://news.ycombinator.com/item?id=19247337