http://www.medscape.com/viewarticle/589256_4 Vitamin D: A Rapid Review: Vitamin D2 and/or Vitamin D3 http://www.medscape.com/viewarticle/589256_4 http://www.medscape.com/viewarticle/589256_4 http://www.medscape.com/viewarticle/589256_4 http://www.medscape.com/viewarticle/589256_4 http://www.medscape.com/viewarticle/589256_4 http://www.medscape.com then D3 is a better choice than D2. http://www.medscape.com/viewarticle/589256_4