The biological vitamin D assay of low-potency materials with special reference to the role of the mineral content of the diet

Abstract

In a vit.-D assay of low-potency butter or margarine the large intake of fat affects the development of the "line" only by virtue of its decreasing the intake of the rachitogenic diet and therefore of the salt mixture. The healing of rat-rickets by a standard dose of vit. D is inversely proportional to the intake of salt mixture and a very low intake produces healing in the absence of the vit. Therefore low-potency fats are most reliably assayed by equalization of the salt-mixture intakes of assay and "standard" rats.