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D3 or not D3, That is the Question

December 16, 2011 @ 4:00 am
posted by Dr Ginther

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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