D3 or not D3, That is the Question

December 16, 2011 Leave your thoughts

Vitamin D2 and Vitamin D3 are not the same, and definitely not equal.  D2 and D3 are similar pre-hormones, but different.  D2 (Ergocalciferol) is the plant version.  D3 (Cholecalciferol) is the animal version.

Both pre-hormones need to be converted to their active hormone form in the kidney.  D2 (plant version) will work in us but only lasts 2-3 days.  D3 (animal version) lasts for 2-3 weeks.  That huge difference makes a huge difference in dosage needs.

If you are low in your 25-hydroxy Vitamin D level (blood test), which version you use determines how much you need to take for how long.  I always use D3 for my patients.  This avoids confusion.  D3 is cheaper and you need less of it.  Many people who use D2 to correct a low level need to start all over after a few months.

Most patients in Iowa need close to 2000 units of D3 daily.  That is 10,000 to 15,000 units of D3 per week.  I personally use 2 or 3 capsules of 5000 units each week.  This is cheap and easy.  The same dose in D2 is at least 50,000 units each week!

I recommend that you use D3 whenever possible.

Why are we talking about Vitamin D3 supplements a few days before the winter Solstice, when the sun is lowest in the sky?  In Northern Iowa, since mid-September, I have gotten no Natural Vitamin D from Sunshine.  It will be April before I get any.  For now, I need Vitamin D3 supplements.

Jay Ginther, MD

December 2011

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