Vitamin d supplementation - new meta analysis

When I first listened to episode 152 about Vitamin d, I was positively surprised that all the vitamin d I was gobbling for years was probably not the magical cure to my winter time low energy.
As a biomedical engineer, I have some ability, although rather basic, to read and understand medical papers.
My friends generally think I’m crazy for not taking vitamin d supplementation, and they recently quoted a video on youtube by one dr. John Campbell, where he discusses a new meta analysis study that claims vitamin d supplementation has a significant effect on reducing incidence and severity of covid.

After going through the paper, and reading all the cited papers in the meta analysis, it is clear to me that the case still stands as brought up in episode#152 that vitamin d supplementation actually does not contribute to decreased chances of catching covid or severity of covid when caught.
My question to this forum for discussion is: Why do these papers keep coming up? Why are they cited so much? Why do well known doctors with millions of followers keep sharing this as credible content?
Have a look at the paper yourself here: https://www.mdpi.com/2072-6643/16/5/679
Without going too much in details, read the papers cited in the analysis that match a “good” criteria of their scope. You’ll know what I mean when I say I’m confused why they use this as a measure for how vitamin d supplementation is (according to the study) up to 80% effective in reducing chances of catching covid … ridiculous

Dr. John Campbell is not a medical doctor, but rather a nursing education related PhD. He is not an expert on vitamin supplementation, evidence-based clinical care, epidemiology, infectious disease, and…well, you get the point.

During the pandemic, he and others rose to popularity after promoting conspiracy theories. He, and others, make money from doing this stuff. By recommending vitamin D, he can also make money from endorsements, amazon, and so on.

I am aware of this paper and agree with you, these types of studies are not particularly useful. In addition to the findings being highly suspect due to design, note the absence of serum vitamin D levels. It would be really hard to claim supplementation did much without serial vitamin D levels and and exposure data. I suspect this paper will continue to get heat.

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“Why do these papers keep coming up?” - Literally because people keep doing that research & getting that result.

“Dr. John Campbell is not a medical doctor, but rather a nursing education related PhD” - Correct. PhD literally means “Doctor of Philosophy”. In today’s world, we want to avoid confusion with M.D., so we stigmatize the silly non-medical PhDs who would call themselves “Doctor”. But, if any PhD could or should still pull it off, it would PhD in a clinical medical field.

“conspiracy theories” - That’s an emotional pejorative. Come on Jordan, you can do better. Or else, why not just accuse Campbell of “poopyhead thoughts”? It’s on the same level.

Campbell is all about evidence-based medicine. Even when he presents some politician’s speech, it’s to show them citing evidence for once. When he talks vitamin D, he cites papers that show serum levels.

The key difference between you & him, is that he gives a little more credence to evidence that you would consider low(er)-grade. Not every study can be an expensive, flagship study funded by Big Pharma, or by FDA & CDC who get vast private funding from Big Pharma. When a study is retrospective, smaller, done cheaply, etc. Campbell will usually states its limitations - but not dismiss it entirely. Same with Dr Mobeen Syed, another popular Youtuber.

To tip my own hand: I do prefer his approach. I do find it amazing, how often the big, expensive studies will have a big, expensive result, that is, a result that will help Big Pharma sell a $100 or $1000 course of some drug, rather than $10. That’s just me. “You do you.”

“He, and others, make money from doing this stuff.” - And you, Dr Jordan Feigenbaum, have a problem with that? Really? You really went there?

To be clear: Campbell does not, repeat NOT, sell a product line. He gives away his books for free. The only money he makes would be from YouTube ads, a common practice. Is your own BBM Youtube channel, demonetized? I’d be interested to hear.