72 PHYSIOLOGY FOR NURSES 



to the fact that protein is not completely burned in the 

 body but some of the end results of its metabolism are 

 still capable of further oxidation. 



By studying the diets of large numbers of individuals 

 engaged in different vocations, it has been learned what 

 the average amount of each constituent in the diet is 

 and what the total caloric value of the food taken in 24 

 hours should be. The following are samples of average 

 dietaries : 



TOTAL 

 INVESTIGATOR CARBOHYDRATE FAT PROTEIN CALORIES 



Moleschott. 550 gm. 40 gm. 130 gm. 2980 



Ranke. 240 " 100 " 100 " 2324 



Voit. 500 " 56 118 " 3053 



It is seen from these figures that the amount of pro- 

 tein is not subject to wide variations, while reduction 

 in the amount of carbohydrate in some of the diets is 

 accompanied by increase in the amount of fat and vice 

 versa. These energy-yielding foods are to a certain 

 extent mutually replaceable, but there is a limit to this : 

 fat being more difficult of digestion and also more ex- 

 pensive. On the other hand, when fat is not absorbed 

 properly or not handled properly after absorption, even 

 though there be no evidence of disturbance with the 

 metabolism of protein and carbohydrates, severe nutri- 

 tional disturbances occur, as illustrated by cases of 

 injury to the thoracic duct or of faulty fat digestion, the 

 latter occurring in infancy. 



Agreement has not yet been reached in regard to the 

 amount of protein required in the diet. As shoAvn above, 

 in no instance is it below 100 grams in 24 hours in the 

 average diet. This amount is in excess of what is re- 

 quired for repair of tissue in the adult under normal 

 conditions, a considerable part of the ingested protein 

 being split up to yield energy. Since protein is more 



