THE HYGIENE OF NUTRITION 213 



much protein which is most vigorously condemned. 

 The decisive effect of a large protein allowance upon the 

 metabolism an effect in the direction of a seemingly use- 

 less increase has been mentioned. Other peculiar prop- 

 erties call for discussion. We may conveniently distin- 

 guish the influences proceeding from an excess of protein 

 in the intestine from those which are associated with an 

 excess of nitrogenous metabolism. In regard to the first 

 it may be said that protein far more than the non- 

 nitrogenous foods is capable of generating toxic sub- 

 stances and so of becoming a cause of true auto-intoxi- 

 cation. An unabsorbed surplus of protein is, therefore, 

 to be avoided. 



If, however, the absorption is as complete as can be 

 desired, reasons can still be given for keeping the protein 

 income of the body relatively low and depending largely 

 upon carbohydrates and fats in preference to nitrogenous 

 food. Emphasis has been placed elsewhere on the sim- 

 plicity of the normal oxidation products formed from sugar 

 and fats in contrast to the numerous and rather complex 

 bodies which arise from the working over of the protein 

 derivatives. Carbon dioxid and water are disposed of by 

 the healthy system with apparent ease. The nitrogenous 

 wastes require preliminary treatment by the liver and per- 

 haps by other organs, and must then be removed from the 

 blood by the kidneys. The principal one, urea, is not 

 commonly a source of trouble, but the minor attendants, 

 such as uric acid, are viewed with disfavor. 



One is naturally led to the opinion that high protein 

 feeding must lay a burden upon the liver and the kidneys, 

 but it is probably just to assume that what is a severe 

 tax for one person may not be so for another. The native 

 efficiency of these organs is doubtless as variable as many 

 other inherited qualities. Nitrogenous by- or end-pro- 

 ducts, whether having their origin in the decompositions 

 within the colon or in the metabolism, are presumably 

 responsible for the premature fatigue of which we have 

 spoken. An additional injury which may be laid to their 



