“Light equals D.” – early vitamin D pioneer Alfred Fabian Hess, in 1923. How has modern science and heath-care reporting lost track of this foundation in vitamin D’s role in human health?

One of the common mistakes people make when discussing vitamin D is assuming that it is a dietary vitamin like the others. But vitamin D is unique for a few reasons.

First, it’s not really a ‘vitamin.’ Vitamin D researchers recognize that the production of vitamin D in the body is really the pathway to the production of the hormone called calcitriol – an active form of vitamin D. That hormone is one of the most powerful hormones in the body.

Second, it’s most natural and abundant source is not from food — a fact that Sun Scare proponents seem willing to distort. By natural design, sunlight exposure to the skin makes most of our vitamin D.

According to the University of California-Riverside, “Hess and Weinstock confirmed the dictum that ‘light equals vitamin D’. They excised a small portion of skin, irradiated it with ultraviolet light, and then fed it to groups of rachitic rats. The skin that had been irradiated provided an absolute protection against rickets, whereas the unirradiated skin provided no protection whatsoever; clearly, these animals were able to produce by uv irradiation adequate quantities of “the fat-soluble vitamin”, suggesting that it was not an essential dietary trace constituent.”

To read UC-Riverside’s account of this moment in vitamin D research history click here.