Researches on Vitamin A. VII. Notes on the Factors influencing the Value of Milk and Butter as Sources of Vitamin A

Abstract

DURING the last few years we have had occasion to examine a large number of samples of butter and milk for the presence of vitamin A, and from the examination of this material, drawn from many sources and representing a wide variety of products, we have obtained results which throw some light on the factors governing the distribution of the vitamin in these important foodstuffs. At the same time we have made a number of controlled experi- ments to gain more definite information on one or two points which have arisen during the course of the work. In the present paper we have put together what we regard as the most important results we have obtained, in spite of the fact that the whole does not form a connected survey.