The proper claim is that raising people from deficient (<20ng/ml) to a sufficient level (>30ng/ml ideally) should improve outcomes. Sometimes looking at a subset of those who started deficient is good enough to find such an effect, but sometimes it isn't, such as if the dose used was not high enough to raise people up enough, particularly common if the subjects weights were high which requires higher intakes to move the needle a lot, so other subset analysis look at norm-weight subjects. Proper study guidelines were published in the mid 2010s and meta-analyses like this one that aggregate many studies that don't conform to these guidelines are just as invalid as individual studies that don't.
Nonesense. It's well established that dietary D3 (or D2, but D3 is better) clearly incleases 25(OH)D serum levels. It is that serum biomarker whose deficiency (levels below 20ng/ml or 30ng/ml) that has the largest association with higher risk of dozens of diseases as well as all-cause mortality. You can defend your phrasing by saying that "not well" just means one has to take a lot of it. Yes, there is a wide variety of dose response, which is why it's best to test blood levels to titrate supplementation amount.
Is the blood level diagnostically significant with vit D? Or is this something like magnesium where serum levels can be normal while having a magnesium shortage? IIRC vit d is fat soluble, does the body store any excess quickly, or does it linger around?
The goal of this study was to investigate whether the relationship between body composition, serum 25-hydroxyvitamin D (25OHD), vitamin D in subcutaneous (SQ) and omental (OM) adipose, and total adipose stores of vitamin D differ among OB and C. ... In summary, although OB had significantly greater total vitamin D stores than C, the relationship between serum 25OHD and fat vitamin D and the overall pattern of distribution of vitamin D between the OM and SQ fat compartments was similar.
The academic paper this story is based on is here: https://nature.com/articles/s43587-024-00793-y
Despite the linked story title only mentioning omega3, the paper was about 3 interventions, that, vitamin D, exercise and found reduced epigenetic age from the interventionts, with bigger anti-aging benefit as they were combined.
With respect to vitamin D specifically, this isn't by itself good evidence vitamin D reverses aging. But it is consistent with the totality of evidence that being vitamin D deficient probably (causally) speeds aging. And it mildly increases the overall weight of evidence of a connection.
As with much vitamin D research, it would have been better for the intervention to have been titrate vitamin D supplement amount to achieve an optimal target range (eg 30-60ng/ml) rather than using a fixed relative moderate dose (2000IU).
The problem with a fixed dose is that surely some subjects started severely deficient, some mildly, and some had sufficient levels. The moderate but not very high fixed dose will have helped many in the middle group climb out of deficiency, not been enough for many in the 1st group to bring them fully out of deficiency, and been unnecessary for those in the 3rd group, so the study ends up seeing a weaker overall effect averaged over all subjects. This is well known within the vitamin D world, eg see https://x.com/KarlPfleger/status/1732514710715514883, but somehow has not permeated to be widely enough understood, even within the scientific community (or the Hacker News community).
No, ample evidence shows that vitamin D (or vitamin D deficiency at least) is causally related to multiple diseases. The evidence is pretty overwhelming. Eg here's a just published review on D deficiency causality for Covid based on applying Hill's Criteria for causality https://www.mdpi.com/2072-6643/17/3/599 and a prior 2022 paper on the same subject https://pubmed.ncbi.nlm.nih.gov/35308241/
Some vitamin D skeptics claim tat there's insufficient evidence from RCTs but few people question the causality of smoking's influence on cancer despite no RCTs for that---that relationship was established also via Hill's Criteria.
> No, ample evidence shows that vitamin D (or vitamin D deficiency at least) is causally related to multiple diseases.
Both my statement and yours can be true. Having a deficiency in an essential nutrient can be causal for bad outcomes while, at the same time, having the correct amount or excess can be non-causal but correlated with positive health outcomes.
I've collected the results from all 4 papers including the links to all 4 in a Google spreadsheet for easily lining up the results for each stage of Covid: https://docs.google.com/spreadsheets/d/1a5twV0x-TlHzd2AVr9e1...
1 tab for the links & underlying number of studies/patients & 1 tab for the results.
4 big systematic meta-analyses since Dec'21. Consistent results from all 4: Low D levels or not supplementing D has 1.5x-3x worse Covid risk at all stages (infection to mortality).
One reason getting these from the evolved route may be better is because feedback mechanisms stop making the beneficial substance when the body has enough, which may not happen via intake by other methods. This is the case for vitamin D from sun vs oral D supplements. Serum levels stop going up when they reach a natural adequate evolutionary range if it's coming from sun. I don't know if that's true of NO or not. Or of melatonin from the near-infra-red wavelengths, but I wouldn't be surprised.
> This is the case for vitamin D from sun vs oral D supplements.
Wait, has there been a study suggesting this? This implies that there's a narrow optimal range and exceeding it causes problems. Seems you would see this in the supplement trials. Vitamin D toxicity doesn't occur until you take many times the RDA for months, and presumably none of the supplementation trials went anywhere near that high. https://www.mayoclinic.org/healthy-lifestyle/nutrition-and-h...
I thought this piece spent too much time arguing about the wrong things (such as evolutionary stuff). I added 3 comments on what I think are the most important points with links to scientific research to the comments on Apr 22. Just search for Pfleger using find-in-page to read them.
For detailed treatment of this see this thread on X: https://x.com/KarlPfleger/status/1732514710715514883