What form of Vitamin D is best? D3

The debate over whether vitamin d is best for us in D2 (ergocalciferol) or D3 (cholecalciferol) appears to be settled with D3 appearing to be significantly more potent for us. Most supplements are D2. So if you're buying vitamin D for anti-cancer purposes, make sure it's D3 you are getting. In the abstract below you'll see that the researchers come down hard on D2 and say it isn't "suitable for supplementation or fortification."
I hope milk makers are taking note. Almost all milk is fortified with D2.

The case against ergocalciferol (vitamin D2) as a vitamin supplement Am J Clin Nutr. 2006 Oct;84(4):694-7 "vitamin D3 has proven to be the more potent form of vitamin D in all primate species, including humans...Despite an emerging body of evidence suggesting several plausible explanations for the greater bioefficacy of vitamin D3, the form of vitamin D used in major preparations of prescriptions in North America is vitamin D2. The case that vitamin D2 should no longer be considered equivalent to vitamin D3 is based on differences in their efficacy at raising serum 25-hydroxyvitamin D, diminished binding of vitamin D2 metabolites to vitamin D binding protein in plasma, and a nonphysiologic metabolism and shorter shelf life of vitamin D2. Vitamin D2, or ergocalciferol, should not be regarded as a nutrient suitable for supplementation or fortification"

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