Some Differences in Action Between Irradiated Ergosterol and Cod Liver Oil

Abstract

In a recent communication 1 it was reported that chickens require a much greater amount of irradiated ergosterol than its cod liver oil equivalent in order to protect them against leg-weakness. The potency of the irradiated ergosterol preparation used in these experiments has been standardized on rats on the basis of cod liver oil, as is the custom in the United States. In another communication 2 from this laboratory, it was shown that irradiated ergosterol, when given to rats in inadequate amounts, acted differently from cod liver oil, in that it raised the inorganic phosphorus of the blood to its normal concentration without healing the rachitic lesion.

The action of these two specific antirachitic agents is likewise not identical in relation to infantile rickets. This winter, in the course of an extended series of observations, it was found that 20 drops of a standard preparation of irradiated ergosterol (viosterol) in some instances failed to fully protect infants from rickets, although the inorganic phosphorus concentration of the blood was maintained. According to the standard biological test, 20 drops of this preparation is equivalent to 10 teaspoonfuls of cod liver oil. In one instance in which mild rickets developed although this amount of irradiated ergosterol had been given daily, 6 teaspoonfuls of cod liver oil subsequently brought about healing in a few weeks as demonstrated by radiographs. In other words, 6 teaspoonfuls of cod liver oil brought about cure where 20 drops of irradiated ergosterol (supposed to be the equivalent of 10 teaspoonfuls of cod liver oil) failed to afford complete protection. Such a result does not mean that the antirachitic action of irradiated ergosterol is weak or unreliable, for undoubtedly complete protection or cure would have been brought about by a larger dosage.