Sunday, August 5, 2012

Vitamin D3 or D2?

I often have new patients tell me that their doctor prescribed them vitamin D2 (50,000 IU) for eight weeks to improve their blood levels of vitamin D. I have even had patients placed on this prescription for years while repeat testing revealed their vitamin D blood levels to remain low or barely adequate (30 ng/ml). My response has been to encourage a switch to 5,000 to 10,000 units of vitamin D3 per day with repeat testing. In most cases, their vitamin D levels improve and the patient can then be placed on a maintenance dose of 2,000 to 5,000 IU/day.

In a study published in the Journal of Clinical Endocrinology and Metabolism, researchers (Heaney, R.P., et al. 2011) at Creighton University found "D3 is approximately 87% more potent in raising and maintaining serum 25(OH)D concentration and produces 2- to 3-fold greater storage of vitamin D than does equimolar D2."

They concluded, "Given its greater potency and lower cost, D3 should be the preferred treatment option when correcting vitamin D deficiency."

Heaney, R.P., et al. 2011. Vitamin D3 is more potent than vitamin D2 in humans. Journal of Clinical Endocrinology and Metabolism. doi:10.1210/jc.2010-2230.

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