How Does Sunlight Help Synthesize Vitamin D?

[katytanzer]

Most vitamins seem to be obtained from food, so how does sunlight increase the amount of Vitamin D in the body?

Edited April 16, 2017 by katytanzer

[Function]

UV light promotes the formation of vit. D in our body by catalyzing certain metabolism pathways.

 

Downstream, calcitriol (1,25-dihydroxycholecalciferol, aka 1,25-dyhydroxyvitamin D or vit. D3) is formed by liver and kidneys out of 'inactive' vit. D.

 

It is calcitriol which will act in your Ca and P metabolism (most importantly it will promote intestinal absorption of both minerals).

 

The formation of vit. D3 is also helped by parathormon (parathyroïd hormon, PTH) (which also promotes the intestinal absorption of Ca and P, and inhibits renal excretion of Ca and promotes renal excretion of P, which results in a net rise of serum Ca levels and decrease of net serum P levels) ... I could go much further into detail on Ca and P metabolism and bone resorption etc. and the role of PTH in those mechanisms, but that would lead us too far for your question.

 

I suggest you read the text under the heading "Synthesis in the skin" on the Wikipedia page of "Vitamin D".

Edited April 16, 2017 by Function

[Velocity_Boy]

Vitamin D synthesis from exposure to sunlight actually consists of a series of biochemical steps.

 

So, first... When you expose your skin to direct sunlight...actually to UVB rays...Those wavelengths penetrate your skin. And then, your body activates the precursor for vitamin D3 that's found in your skin cells. This is the first form, or prototype, of vitamin D goes to your liver, where it gets extra hydrogen and oxygen molecules.

 

After the liver..this newly manufactured vitamin D compound then goes to your kidneys where it picks up one more set of hydrogen and oxygen molecules. This be the form that make the ACTIVE type of vitamin D..The version we really utilize...that's called Calcitriol.

 

This is the finalized form of vitamin D helps your bones absorb calcium and keeps your immune system working in optimal fashion, in addition to other beneficial physiological actions.

Edited April 17, 2017 by Velocity_Boy