How does the quality of vitamin D2 compare with D3?

by Thomas
( Maine)

There has been a great deal of controversy regarding the quality of D2 compared with D3. Doctor Michael Holick, Professor of Medicine, Physiology and Biophysics at the BU Medical Center and author of The Vitamin D Solution: A 3-Step Strategy to Cure Our Most Common Health Problem has been referred to by Dr. Mark Hyman as the world's leading authority on Vitamin D. Dr. Holick has recently researched this question of the quality of D2 and concluded on page 41 "I demonstrated that D2 is just as effective as D3 and put to rest this long standing myth" ( i.e.that D2 is less effective than D3).

He lists the Vitamin D content of various food and I noticed that the highest concentration of vitamin D -by far- is sun dried Shitake mushrooms with 1600 IU's in just 3.5 ounces.This is much higher, ounce for ounce, than even cod liver oil or wild salmon. Of course the best source of Vitamin D is from the sun- under the right conditions, which he outlines in his book.

So the question is: Do you know of any recent research findings which would contradict Holick's conclusions. Thanks so much for your thoughts!