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May 13, 1950


Author Affiliations

Iowa City

From the State University of Iowa, Iowa City.

JAMA. 1950;143(2):177-181. doi:10.1001/jama.1950.82910370004009

The term vitamin D is applied to sterol derivatives that have antirachitic properties. Although several forms of vitamin D are known, only two at present are of practical importance. It is appropriate to consider that all antirachitic drugs and foods owe this property to one or both these forms, which are known as vitamin D2 and vitamin D3. Vitamin D2 is prepared by activation of ergosterol, a vegetable sterol. Vitamin D3 results from activation of 7-dehydrocholesterol, an animal sterol. Activation is carried out by exposure to ultraviolet rays or to low velocity electrons. Vitamin D3 is the type formed in the skin on exposure to sunshine or ultraviolet rays. The fish liver oils contain mixtures of these varieties of vitamin D. Tuna liver oil, for example, contains a preponderance of vitamin D, over vitamin D3 and cod liver oil, a preponderance of vitamin D

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