The worthlessness of Vitamin D is mildly exaggerated

This is a refreshingly balanced and honest analysis of Vitamin D studies.

The strongest evidence for Vitamin D is in people who are severely deficient. Bumping up to a normal range can provide some improvements.

The health influencers started noticing that the Vitamin D studies coming out weren't matching their original hype for Vitamin D, so many pivoted to trying to make claims that most people are severely deficient and just don't know it, which provides a convenient out to dismiss the studies that didn't pre-filter for people who were severely deficient. You can find waves of people on social media repeating the idea that almost everyone is Vitamin D deficient and encouraging high dose supplementation still.

Speaking to a doctor who runs Vitamin D labs as part of her annual physical screening process, she's now actually seeing more people who have excess Vitamin D than too little Vitamin D. Upon followup she discovers that patients have listened to a podcast about Vitamin D and started taking it regularly, unaware that they're pushing their levels into the range where it can start doing more harm than good.

Vitamin D is tricky because it lasts for a very long time in the body, which means steady-state supplementation can take a very long time to stabilize. I suggest anyone supplementing for a long time get a blood test, which can be ordered without your doctor if you can't get your doctor on board.

On another topic: Fish oil has also gone through a similar cycle of being hyped up based on early results, with higher powered follow on studies showing much less interesting results.

Even so, it still seems to be a small effect. The author mentions some studies looking at sunlight vs all cause mortality. These, and more recent studies [1] found much higher reductions in all cause mortality from sunlight exposure, of about 30%. It's thought that other factors may be behind this, such as NO production in the skin in response to UV [2].

[1] https://pubmed.ncbi.nlm.nih.gov/32918215/

[2] https://karger.com/bpu/article-abstract/41/1-3/130/328295/Su...

I suspect that blood vitamin D is mainly a marker for how much outdoor exercise people are getting, and that it is the exercise rather than the D which is causal.

I like this author but this post was only weakly intriguing.

More importantly, I'd like to know how long it takes to write a post like this.

Everything I write, I try to research and publish in under 2 weeks.

This post looks like it grew over time. I like that quality very much.