EDIT..Re: What's wrong with that picture?

Supposedly, Vitamin D2 is the poor relation and least effective method in increasing serum levels of 25-hydroxyvitamin D levels, so reports Michael Holick PhD, MD, director of the General Clinical Research Center and professor of medicine, physiology and biophysics at Boston University Medical Center.

"One thousand IU of vitamin D2 daily was as effective as 1,000 IU of vitamin D3 in maintaining serum 25-hydroxyvitamin D levels and did not negatively influence serum 25-hydroxyvitamin D levels," said Holick. "Therefore, vitamin D2 is equally as effective as vitamin D3 in maintaining 25-hydroxyvitamin D status.".................
http://www.sciencedaily.com/releases/2008/01/080102122306.htm


D2 or Ergocalciferol is a fat-soluble sterol: an organic molecule that is found in plants but in insufficient quantities to have much therapeutic effect, but in higher doses via supplementation, will act in much the same way as D3 but only achieving this over a longer time-frame.

D3 though is the supplement of choice, as its beneficial and therapeutic effects are achieved more quickly and are far more efficacious as a result.


EDIT....
Just literally had a phone call while writing this post from the Mother of my future son-in-law, who has bone cancer (Ewings Sarcoma).
He has been an in-patient at UCH Euston London for one week on chemo with a two week break at home in between: this is his third session of high strength combination-chemo within the Hospital.
The Doctors have just stated that the cancer which had metastasized to his lungs had "vanished" and his bone cancer had reduced so much in size from 7cm as to be barely undetectable. They have expressed their absolute amazement.

All this while he has been taking Vitamin D3 at 30,000ius per day on my say so and approval, and I believe has been largely responsible for this most wonderful of outcomes.

Chrisb1.