The Metabolism of Vitamins 



CARL VOEGTLIX 



WASHINGTON 



Discovery of Vitamins 



Until a few years ago it was generally assumed that a complete diet 

 for purposes of proper growth and maintenance of health of the animal 

 body should consist of proteins, fats, carbohydrates, inorganic salts and 

 water in sufficient quantities to furnish an adequate supply of energy and 

 material for the building up of the body tissues. The discovery of certain 

 other substances not related to the above-mentioned food factors, and 

 now considered just as essential for the maintenance of normal metabolism, 

 can be traced back to two distinct lines of investigation ; first, the study 

 of scurvy and beriberi, and, second, feeding experiments with highly 

 purified diets. 



Numerous clinical observations on scurvy ami beriberi, and especially 

 the experimental production of these diseases in the lower animals by 

 Eijkman(c) (1897), and Hoist and Frohlich(a) (1907), called attention 

 to the importance of the diet in the causation of these diseases. Thus it was 

 found that -scurvy does not occur if the diet contains an adequate amount 

 of either fresh meat, fresh vegetables or fresh fruits, and that the disease 

 can be successfully treated by the administration of relatively small 

 amounts of certain fresh fruits and vegetables. These observations, and 

 the fact that prolonged exposure of these foods to temperatures of 100 C. 

 destroyed their prophylactic and curative properties, suggested that the 

 fresh foods contained some hitherto unrecognized food constituents. Ex- 

 perience with beriberi showed furthermore than this disease appears if 

 the diet is restricted to highly milled cereals, whereas people living on 

 foods made from the whole grain are immune against beriberi. -Small 

 amounts of an extract of the portion of the grain removed in the milling 

 process proved to be a powerful curative agent. This led to the conclu- 

 sion that the whole grain and the extracts made from the offal contained a 

 substance or substances which later on were shown by Funk (a) (1911) not 

 to be related to any of the well-known food factors. 



Independent of this work on scurvy and beriberi, some investigators 

 attempted to feed animals on purified diets containing an adequate pro- 



341 



