The Research is pointing to upwards of 87% greater efficacy of D3 over D2. Journal of Clinical Endocrinology and Metabolism.
Full discussion can be read in an excellent article: www.nutraingredients-usa.com/Research/Vitamin-D3-87-percent-more-potent-than-D2-Study
Meta-analysis looks at efficacy of D2 vs D3
Prescription vitamin D (D2) less effective than over-the-counter vitamin D (D3) according to a meta-analysis.
Recently, a review and meta-analysis address this question. The meta-analysis study was led by Professor Dr. Goran Bjelakovic.
Bjelakovic G, Gluud LL, Nikolova D, Whitfield K, Wetterslev J, Simonetti RG, Bjelakovic M, Gluud C. Cochrane Database Syst Rev. 2011 Jul 6;(7):CD007470.
He analyzed 50 randomized controlled trials (RCTs) with a total of 94,000 participants that used some form of vitamin D and reported mortality rates as either primary or secondary outcomes. Within these RCTs, 32 of the studies used D3 (74,000 subjects) and 12 of them used D2 (18,000 subjects). He found there was a 6% relative risk reduction when supplementing with vitamin D3, as opposed to a 2% relative risk increase when supplementing with vitamin D2
Amazingly, this study somehow slipped under the radar and neither the press nor I picked up this study in July. Luckily, Professor Dr. Harvey Murff of Vanderbilt University reviewed this study yesterday in the Annals of Internal Medicine recently, allowing the general public to examine the study once again.
Murff HJ. Review: Cholecalciferol (vitamin D3) reduces mortality in adults; other forms of vitamin D do not. Ann Intern Med. 2011; 155:JC5-04.
