480 METABOLISM, NUTRITION, AND DIET 



FOOD SUPPLEMENTS, THE VITAMINES. 



Numerous workers have shown that it is not sufficient to supply the 

 body with adequate proteins, fats, carbohydrates, inorganic salts and water 

 meeting the standard requirements as regards the caloric value of foods. 

 Formerly these facts were considered as physiologically settled, both by 

 the medical profession and by those interested in animal nutrition. In 

 the next chapter we will find that minute quantities of substances pro- 

 duced by the various ductless glands of the body may profoundly influence 

 the process of metabolism. In like manner, observation indicates that the 

 foods contain similar traces of material supposedly of chemical nature 

 which have an influence on metabolism out of all proportion to their 

 quantity or mass. Such substances have been given the name of vita- 

 mines by Funk. Most food sources, such as meat, milk, fish, vegetables 

 and cereals contain these so-called vitamines. However, the amount of 

 vitamines furnished by each varies widely. 



The Nutritional Diseases. A group of well known diseases of obscure 

 etiology have been investigated on a large scale since the discoveries of 

 Funk. At the present time the diseases of xerophthalmia, of the beri- 

 beri type of neuritis, and the scorbutic diseases are definitely attributed to 

 lack of corresponding specific vitamines in the diet, namely, fat soluble 

 A, water soluble B, and water soluble C vitamines. Other factors in the 

 food are necessary to its complete adequacy. Of these it is evident that a 

 proper chemical balance among the inorganic salts of the diet, as well as a 

 certain bulk and quality to which the digestive apparatus of the particular 

 species of animal may be adapted, plays a vital part in the food sufficiency. 

 Many of these questions are not yet adequately determined. 



Beri-beri and the Antineuritic Vitamine B. In the far East there 

 is prevalent a characteristic nervous disease known as beri-beri. It 

 is characterized by loss of nervous function which comes on relatively 

 suddenly and proceeds to a state of motor paralysis. Beri-beri has been 

 found to be associated with the use of an excessive rice diet and is prevalent 

 in rice eating countries. Chickens, pigeons, and pigs which are relatively 

 susceptible to a neuritis very similar to, if not identical with, beri-beri 

 quickly recover when fed on rice polishings at an early stage of the disease. 

 Such experiments have led to the conclusion that in the polishing of rice 

 a food constituent is removed that is absolutely necessary to the normal 

 growth of the nervous system. This material has been extracted and 

 chemically examined by Funk who describes it as an organic crystalline 

 substance melting at 233 C., chemically resembling pyrimidin. Sub- 

 stances like the rice extract which cause recovery from nutritional diseases 

 of the neuritic type have been given the name, antineuritic substances. 

 Williams prepared an oxypyridine that cured neuritic pigeons in doses 

 of one milligram. 



