Is There Something Wrong About How We Get Vitamin D From Sunlight? I Suspect We Do It In a Very Unnatural Way

Peater Piper

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Always the studies are about direct sun exposure, and never about indirect sun exposure.
I'm unable to find one study I previously read where they measured UV rays in a location where the sky was visible overhead, but a wall was providing shade. UVA rays were reduced in the shade far more than UVB rays, presumably because UVB is more prone to scattering when hitting aerosols. In short, vitamin D synthesis would have been nearly as high as in direct sunlight, and UVA exposure would have been reduced. I did find this study, which shows vitamin D synthesis is possible in a number of shaded scenarios: Vitamin D effective ultraviolet wavelengths due to scattering in shade - PubMed
 

charlie

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Found this article insightful:
 
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yerrag

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What I picked up that's most useful is that -

- in a tree shade, you can get 5% of the UV exposure, compared to direct exposure.
- in a shade by the swimming pool, you can get as much at 17% of direct exposure

I think that it would be a good idea to have a tree that has a good canopy, where one can set up a shade office. If one spends about 5 hours each day working there, it would be the equivalent of 15 minutes of direct sun exposure daily. He can just add another 15 minutes of direct sun exposure, and that would make 30 minutes of sun exposure each day. This makes it much more doable. The nice thing about working in a shade is that you won't be bothered by the glare of the laptop screen.

I think also that the shade provided by the tree can vary from one species to another. So, if a try allows enough sunshine to get through without making the area uncomfortable to sit in, the equivalent exposure may even reach 10%. This would make it possible to work in the shade for 5 hours daily while getting the equivalent of 30 minutes of direct sunshine.

And if a tree isn't practical, why not use a shade sail. I've used an Australian brand, Coolaroo, and it holds up well for many years. The shade sails are rated by how much percentage of sunlight it lets in. A 30% shade sail gives enough shade to give comfort from the sun while allowing more UV exposure. 5 hours working under this shade sail would be equivalent to 1.5 hours under direct sun, which likely more than meets our daily dose of vitamin D from sunlight.

So, if it's natural vitamin D we want, and we are too busy at work, why not hit two birds with one stone and work under a shade?
 
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yerrag

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Found this article insightful:
Really a good find, Charlie.

I read it and it's a very good resource.

It talked about getting infrared A in the morning sun to build up the protection to take the UVB rays during the mid-day, when the sun is most intense.

Since exposure to the sun throughout the day gives us plenty of IR-A rays, I think that if we get to work underneath a shade, we would also be able to get a fraction of the infrared radiation. It would be a lower dose for a longer period. It would be gentle on the skin and would do a lot of good for our metabolism, with the generation of cytochrome c oxidase. So again, it would be killing two birds with one stone when we work under a shade throughout the day, as we don't have to make another effort to get exposed to infrared lamps at another time.
 

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