Vitamin D2 versus D3 – Scientific Evidences

Vitamins D3 and D2 are chemically different. In contrast to vitamin D3, vitamin D2 has a double bond between carbons 22 and 23 and a methyl group on carbon 24 in its side chain. Irrespective of their chemical differences, the human body uses the same enzymatic pathways to transform these vitamins to their pro-hormone (conditional vitamins) and hormone forms. There are ongoing debates in the literature and among the health and scientific communities as to the comparative potency or effectiveness (i.e., bioavailability) of these two chemical forms of vitamin D. However, both forms are recognized worldwide and in the U.S. as acceptable sources of this vitamin for foods and supplements (FDA 21 CFR 184.1950 and 21 CFR 172.379).