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Comment by Alex3917 | Hacker News Reader

The toxic dose is 4,000 IU per day though, so you would normally want to be taking well below that except maybe on a short-term basis.

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That seems low, considering that 5000iu softgels are very readily available (eg the vit D supplements at Costco).

Edit: acute toxic dose not established, chronic toxic dose >50k iu/day. https://www.medscape.com/answers/819426-102369/at-what-dose-...

Edit2: this article lists 4000 IU/day as the generally recognized as safe level https://www.healthline.com/nutrition/vitamin-d-side-effects#...

Costco's vitamin D softgels are 2000 IU, not 5000.

5000 IU softgels are definitely sold OTC though: https://www.naturewise.com/products/vitamin-d3-5000-iu-360-c...

Nature's Bounty D3 125mcg (5000IU), Costco item #1106007

So not Kirkland Signature, but sold there.

As far as I'm aware Vit D toxicity has been observed in much higher doses than 4000 IU/day. Do you have a quote for the 4000 IU/day figure?

The skin produces up to 10,000 IU/day after exposure to UV light⁰. The same study I'm quoting shows toxicity levels at over 20000 IU/day for adults. One person in the study has taken 156,000–2,604,000 IU/day for 2 years!

⓪ - https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6115827/

The production in the body is self-regulating though, so you can't overdose from sun exposure. Supplements can bring you over the limit, because you absorb what you're given.

You are arguing a point I didn't make. My point was to his statement that 4000 IUs/day were toxic (without stating any basis for that number), while the study I quote claims that the body produces up to 10000 IUs/day – so clearly the toxicity limit is not an unqualified 4000 IUs/day. Perhaps in some people toxicity appears at lower doses while in other people at higher doses.

I'm not really disputing the 4k not being toxic. Just the way I understand it, even though you can produce up to 10kUI through the skin should have no relation to the toxicity level being below or above 10kUI.

4000 IU is the tolerable UL (upper limit).

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