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General Science => Question of the Week => Topic started by: thedoc on 03/12/2016 15:11:07

Title: QotW - 12.08.11 - Is making vitamin D akin to human photosynthesis?
Post by: thedoc on 03/12/2016 15:11:07
Hello I'm David from The States and i have 2 questions about the same thing.

I heard that we get vitamin D from the sun if that's true does that mean that to a point we go through a kind of photosynthesis?

And, if so, does sunblock block the Vitamin D getting to us?

Seth Raven
Asked by David Wood

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Title: Re: Is making vitamin D human photosynthesis?
Post by: lujainthatsme on 19/07/2012 00:18:19
Good Question , ummm... well plants photosynthesis in need of food. Plants obviously won't live if they can't make or have food. For humans vitmain D isnt exactly food. Even though it is a very important vitamin , especially for our bones , we humans can probably live without vitamin D . Our bones might weaken , we might not even be able to move without this very important vitamin. But we could just manage to survive without it , so ... No , making vitamin D isn't human photosynthesis.
And also if using SPF 8 blocks it literally blocks about 95% of the sun rays blocking with it the special vitamin.
 :) :) :)
Well , I hope this helps! 
Title: Re: Is making vitamin D human photosynthesis?
Post by: evan_au on 21/07/2012 23:12:29
In common usage, "photosynthesis" refers to plants producing sugar and oxygen from carbon dioxide and water plus light using chlorophyll.

However, in a more general sense, any chemical reaction which is activated by light (photons) could also be called "photosynthesis".

Since Vitamin D is produced by the action of sunlight, it could be called photosynthesis, in this rather unconventional way - but it's best to avoid it, as it will bring up visions of green-skinned humans!

Sunblock does reduce the level of Ultraviolet light reaching your skin - it's a tradeoff between reducing the incidence of skin cancer and increasing the incidence of osteoporosis.
Title: Re: QotW - 12.08.12 - Is making vitamin D akin to human photosynthesis?
Post by: amplexity on 10/08/2012 08:01:27
Photosynthesis is a special biochemical process that uses solar energy to create relatively complex and energy-rich sugar molecules from CO2, a simple and low-energy source of carbon.  Essentially, solar energy is stored in the chemical bonds of sugars.  Because of this, plants are able to make their own food.

The creation of vitamin D in humans is not similar to photosynthesis for two reasons.  First, we are not converting solar energy into chemical energy, and second, we are not using these molecules for food.   

In humans, vitamin D is created from a precursor molecule that is already present in our skin.  The sun's energy is used to slightly change this pre-existing precursor molecule into a form that is more usable to our cells.  Once modified by solar rays, this early form of vitamin D will be later modified in the kidneys before becoming functionally mature. 

UV light is especially important in this process.  Using sun block reduces the amount of UV reaching your skin cells, so it would reduce vitamin D production.  However, if you spend several hours in the sun, it is likely that enough UV radiation is penetrating this protective layer and enabling your body to make sufficient quantities of vitamin D.
-Matt F, Washington State