THE CAROTENE AND VITAMIN A CONTENT OF MARKET MILKS

Estimates of the vitamin A requirements of the healthy adult vary markedly, 1 but it is generally believed that a good diet should provide from 3,000 to 4,000 U. S. P. units of vitamin A each day. Green, leafy vegetables provide appreciable quantities of provitamin A (carotene) but other excellent sources of vitamin A such as milk and dairy products which contain butter fat are usually relied on to supply significant amounts of the normal requirements. While there are numerous reports on the carotene and vitamin A contents of milk produced under experimental conditions 2 and a few analyses of isolated samples of market milks, 3 there are no published data dealing with a large volume of market milk over an extended period of time. Most workers report potencies between 10 and 60 U. S. P. units per gram of butter fat, but a few values fall outside these limits.