The antirachitic activity of previtamin D₃

Abstract

Abstract A prophylactic test (chick assay) was carried out with pure pre‐vitamin D 3 . The apparent antirachitic activity was found to be 35% of that of pure vitamin D 3 . This result is discussed in connection with the kinetics of the interconversion of previtamin D 3 ⇆ vitamin D 3 . The observed activity may be interpreted as originating exclusively from vitamin D 3 formed in the test animal.