THE "VITAMIN" HYPOTHESIS AND THE DISEASES REFERABLE TO FAULTY DIETf

The studies of the past decade have revealed the fact that the adequate diet of the higher animals must contain protein of the type known as "complete," by which we mean a protein yielding all the amino-acids that are required in the nutrition of an animal. It must contain, in the form of suitable salts, at least nine of the inorganic elements, namely, calcium, magnesium, sodium, potassium, iron, chlorin, iodin, phosphorus and sulphur. "The sulphur must be in organic combination in the form of the amino-acid cystin. The diet must supply a suitable quota of energy in the form of protein, carbohydrates and fats, and must, in addition, contain certain substances of unknown chemical nature, to which Funk gave the name "vitamins." There are still differences of opinion concerning the probable number of these substances. There are two ways of attacking the solution of this problem. We may attempt to show that the several syndromes that are referable to faulty diet can be relieved by the administration of such preparations as make it certain that the relief is not brought about by any known and well recognized constituent of the, diet. For each of the syndromes now usually spoken of as "deficiency" diseases, which can be conclusively demonstrated to be relieved by such a method, the existence of a substance of the class frequently designated as "vitamins" is demonstrated. Successful attempts in this direction have been limited to two syndromes. Beriberi, which is recognized as being due to the lack in the diet of a sufficient amount of a substance, which is an organic compound, and of which an animal requires only a very small amount, and more recently, a type of xerophthalmia which results from specific starvation for a substance that is especially abundant in the fats of milk and of egg yolk, but is found in all foods which contain cellular struc-