INTRODUCTION 17 



tioning similar to experimental animals, used to establish the value 

 of new foodstuffs. Here, at least, there is the added advantage of 

 successfully applying the various principles of nutrition and sharply 

 terminating the unnecessarily protracted period. In this connection, 

 it is not impossible to make immediate use of the enormous amount 

 of information obtained on the subject, both before and during the 

 war, especially by the United States and England. During the past 

 few years, virtually all foodstuffs have been tested as to their nutritive 

 value and their vitamine content. Although most of the data secured 

 are the results of animal experiments, they are, with a few reserva- 

 tions, directly applicable to man especially as it has been demon- 

 strated that there are no vital differences between the findings 

 obtained with man and those with animals. 



In general, it may be said that during the war, and after, there 

 was a disarrangement of the nutritional elements resulting in a 

 decreased consumption of protein and fat and a greater intake of 

 carbohydrate, together with a diminution of vitamines. It should 

 be noted here that the more important dietary constituents, in com- 

 parison with the physiologically inferior ones, have increased greatly 

 in price, so that there is this danger to contend with in addition to 

 the element of scarcity. Now, when a well-planned animal experi- 

 ment is undertaken, all factors are controlled as far as possible except 

 that one whose influence upon the organism is being determined. 

 Quite another state of affairs confronts us in the case of nutrition 

 investigations on man, where conditions arise which are only rarely 

 met with in animal experiments. If there is a lack of one constituent, 

 then it is almost certain that the entire choice of diet is not correct. 

 For example, if the protein content of the diet is too low, it is at the 

 same tune apparent that the carbohydrates are present in excess, 

 that the vitamine content is diminished, and that the inorganic 

 elements are inadequately grouped. It is easily possible that right 

 at this point is where we must search for an explanation of the 

 pathologically occurring avitaminoses, the etiology of which it is so 

 difficult to establish. If in such a case as mentioned above, the 

 missing factor in the diet is supplied, good results do not follow, for the 

 reason that still other factors have not been taken into consideration. 



Under certain circumstances, a seemingly well chosen diet may 

 prove to be inadequate, particularly when special demands are made 

 upon the individual, such as hard work, growth, birth, and nursing. 



