Getting Your Vitamins, But Are You Getting Your Provitamins?

Vitamins were discovered many years ago. The debilitating
disease of Rickets mid 1600s described by Whistler and Glisson and the
condition of bone pains, fractures, and muscle weakness are both now known to
be the cause of very low vitamin D.  By 1918,
Sir Edward Mellanby discovered the micro-nutritent lacking in cases of rickets
was something that was soluble in fat which was the clue that lead to Goldblatt
and Soames to link this to a compound in the skin, which in turn led to the
discovery of the chemical structure of vitamin D by Windaus. Oddly, the
discovery of Vitamin D followed the physiologic course the molecules encounters
in our bodies. It has to do with what has now become the principle of
provitamin and previtamins. And I’m adding a bit of philosophy of my own to the
Whistler-Glisson-Mellanby-Goldblatt-Soames-Windaus compound's elucidation! The two main types of Vitamin D are D2 and D3. You
skin makes Provitamin D3 , it’s the most primitive form of the vitamin D3, it
cannot be vitamin D3 and it is not directly converted to vitamin D3. Within the
skin the provitamin D3 is converted to previtamin D3 which is then converted in
the liver to actual Vitamin D3 also called 25-hydroxyvitamin D3. Interestingly
this is not the active form of the vitamin D3. Active vitamin D3 is
1,25-hydroxyvitamin D3, which is made by the kidney. It is actually what is called
calcitriol. Or as I like to think of it as “post-vitamin D3” reminding me that
it is made next in the physiologic cascade!


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