The Big Vitamin D Mistake

Re:The Big Vitamin D Mistake by pkaye on Thursday December 07, 2017 @01:23AM (#15868085)

Because of impaired kidney function, I get my vitamin D levels monitored every month. Yes supplements can take 2-3 months to increase the levels. The sun actually works pretty good if you can stay outside 15 minutes in noon sun. But that's difficult in the winter months.

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Re:The Big Vitamin D Mistake by Johnny555 on Thursday December 07, 2017 @01:29AM (#15868115)

I've read varying reports of how much sun you need to generate a day's supply of vitamin D, but rarely do they mention how much skin needs to be exposed.

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.

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Re:The Big Vitamin D Mistake by appleiigs on Thursday December 07, 2017 @02:07AM (#15868269)

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-...

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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.

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Re:The Big Vitamin D Mistake by pkaye on Thursday December 07, 2017 @02:34AM (#15868367)

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.

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Re:The Big Vitamin D Mistake by twobyfour on Thursday December 07, 2017 @07:19AM (#15869415)

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.

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Re:The Big Vitamin D Mistake by cellis on Thursday December 07, 2017 @01:42AM (#15868169)

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.

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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.

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Re:The Big Vitamin D Mistake by astura on Thursday December 07, 2017 @01:46AM (#15868197)

Would depend on how dark your skin is.

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Re:The Big Vitamin D Mistake by timewarrior on Thursday December 07, 2017 @01:27AM (#15868106)

Another big challenge in winter months is that people are so covered with warm clothes, that even going out in Sun doesn't help much.

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Re:The Big Vitamin D Mistake by pkaye on Thursday December 07, 2017 @01:30AM (#15868120)

I wonder if glass windows would block out the benefits?

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Re:The Big Vitamin D Mistake by rollulus on Thursday December 07, 2017 @01:45AM (#15868188)

Yes it does block [1]. Coincidentally I was discussing this with a co-worker last week.

[1]: http://www.sciencefocus.com/qa/can-you-absorb-vitamin-d-thro...

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Re:The Big Vitamin D Mistake by Gibbon1 on Thursday December 07, 2017 @01:52AM (#15868223)

Ordinary window glass blocks 90% of UV-B which is needed to produce VitD.

I do remember reading years ago about a sanitarium in the late 1800's - early 1900 where the windows in the sun rooms were quartz glass.

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Re:The Big Vitamin D Mistake by mjevans on Thursday December 07, 2017 @01:37AM (#15868155)

Anecdotally, a lot of window products have built in films, coatings, or dopants that reduce UV exposure and possibly other portions of the spectrum.

I would /guess/ that pure (greenhouse?) glass, maybe not even visibly transparent, would be effective.

Both could be worth studying if someone hasn't already.

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Re:The Big Vitamin D Mistake by AstralStorm on Thursday December 07, 2017 @03:55AM (#15868636)

Glass itself blocks a lot of UV. Even not doped.

There exist optically transparent plastics that do not.

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