I did some searching...
"John Jacob Cannell, MD, executive director of The Vitamin D Council, notes that the skin makes 10,000 IU of vitamin D after 30 minutes of full-body sun exposure. He suggests that 10,000 IU of vitamin D is not toxic."
https://www.webmd.com/osteoporosis/features/the-truth-about-...
Re:The Big Vitamin D Mistake
by AstralStorm on Thursday December 07, 2017 @03:54AM
(#15868631)
Except that 10000 IU is mostly localized in skin and released a bit slower.
For it, my face and arms are exposed. I walk in the bay area sun for 15 minutes after lunch. Doing this regularly over a month or two will boost my numbers from the mid 20s to mid 30s.
Not to mention it needs to be adjusted for skin tone. The whole reason that humans have a range of skin tones is that paler skin allows for better vitamin D absorption at higher latitudes.
Depends on a lot of things as you mentioned, but also especially on your pigmentation/levels of sunburn. I'm very dark skinned, so I need a lot longer for UV rays to penetrate.
Re:The Big Vitamin D Mistake
by thinkingemote on Thursday December 07, 2017 @11:04AM
(#15871198)
Note that in the winter months even if you're naked outside in the UK you won't get any vitamin D, the sun is too low, the latitude (about same as Alaska) too high.
Face only? Face and arms? Entire upper body? Entire body?
Is there some online resource for this with time of year and latitude corrections? I imagine there's quite a difference between vitamin D production in noon sun in Fairbanks Alaska versus Miami Florida.