A survey of the literature during the past year reveals that two types of problems have been uppermost in the minds of investigators. One group were eager to add to our knowledge of rickets and pellagra; to prove whether the etiology of these two could be traced to vitamine deficiency in as definite a way as beriberi and scurvy can. This group has not as yet solved the problem, though they have made it reasonably clear that the factors involved in the onset of these diseases are more than one; that, at best, a vitamine deficiency explains but part, though possibly an important part, of the story.

Another group have undertaken a careful survey of the factors influencing the vitamine content of foods. Of particular significance are these facts that have been brought out: that the vitamine content of plant food depends upon the type of soil on which it is grown; and that the vitamine content of animal food depends upon the type of plant food on which the animal feeds. The wide variation in vitamine content of various samples of cow's milk is now clear. Equally important is the fact that much of the vitamine content of a food depends upon its method of preparation. In this connection it has been shown that oxidation (aeration, exposure to air, oxidizing agents) has a greater destructive effect on vitamines than heat.

Rickets And Fat-Soluble A

(See page 128)