Fat Soluble Vitamins

For many years the inference might have been drawn from general premises that butter fat is low in antirachitic potency.If butter fat were not poor in this dietary essential the incidence of rickets in children fed on cows' mi]k should be a very rare occurrence, but as a matter of fact it is well known that the vast majority of infants fed cows' milk develop rickets during the winter months.Some years ago, however, Mellanby (1) in his pioneering experiments was very much impressed with the power of butter fat in protecting puppies against deficient calcification of bone.But he found that cod liver oil was far superior.MeCollum, Simmonds, and Becker, and Shipley (2) found that while butter fat contained the calcium depositing factor, it was present in much smaller amounts than in cod fiver oil and in other fish oils which they examined.McCollum, Simmonds, Shipley, and Park (3) found that 3 per cent of cod liver oil prevented the occurrence of rickets while even 20 per cent of butter fat failed to induee normal bone growth.Jones, Steenbock, and Nelson (4), seeing to duplicate the experimental work of others, which was designed to point out the disproportionate activity of butter fat and cod liver oil in their ability to cure ophthalmia as contrasted with rickets, came to the conclusion that cod liver oil might in certain instances be 200 times as active as butter fat in inducing normal calcification of bone.In 1924 experiments from this laboratory (5-10) as well as those from the laboratory of Hess (11-16) showed definitely that *