Comment by chasebank | Hacker News Reader

Comment by chasebank | Hacker News Reader

I remember reading about how the current recommended dose of Vitamin D was a statistical error in a study and has since been corrected to the tune of 10-11x higher.

"The recommended daily intake of vitamin D has a long history, originally set at 400 IU/day in the early-to-mid 20th century, including the 1970s, primarily to prevent rickets in children and bone disease in adults. In 2010, the Institute of Medicine (IOM) updated the recommendation to 600 IU/day for most adults and 800 IU/day for those over 70. However, a major statistical error in the IOM’s analysis was later uncovered by researchers, who showed that the calculation underestimated the amount needed to achieve sufficient blood levels of vitamin D in 97.5% of the population. Their corrected analysis suggested a required intake closer to 7,000 IU/day, an order of magnitude higher. Despite this, most official health organizations have not revised the RDA, and the 600–800 IU/day guideline remains standard." [chatgpt summary]

https://www.grassrootshealth.net/blog/iom-miscalculated-rda-...

It should be said that there are experts that still argue strongly that we shouldn’t casually take large doses of Vitamin D. It’s not actually a vitamin. It’s a steroid hormone.

You can easily be misled about how much vitamin D you need because the skin makes a huge amount of it when exposed to sunlight.. but it does that as part of the process of protecting itself from sunlight, not because the body necessarily needs that much vitamin D.

Before you take large doses you should read and understand these articles.

https://www.devaboone.com/post/vitamin-d-part-1-back-to-basi...

https://www.devaboone.com/post/vitamin-d-part-2-shannon-s-st...

https://www.devaboone.com/post/vitamin-d-part-3-the-evidence

I thought follow up work also showed it's questionable whether dietary vitamin D actually has any of the benefits that you get through solar vitamin D?

Yes, 90% of the world’s population does not absorb dietary vitamin D well, which should make people skeptical of this result.

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?

Yes, from https://pmc.ncbi.nlm.nih.gov/articles/PMC5577589/

  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.

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