PRACTICAL CONSIDERATIONS. 701 



lead us to believe that instead of devoting an undue amount of time to 

 fictitious "nitrogen balances" and an attempt to curtail nitrogen to an 

 extraordinarily low point, the character of the nitrogenous material 

 ingested, including the food accessories, should be carefully considered, 

 and then and not until then can the ultimate reduction of protein be 

 properly studied. 



In connection with the study of low protein and the value of the 

 surplus protein of the body, a complementary condition should be 

 studied in which, after the reduction in protein and its concomitant 

 body-loss, there should be realimentation with low nitrogen intake to 

 minimize nitrogen storage but accentuate the return to normal weight. 

 Under these conditions the true value of the nitrogen storage to the 

 body would be clearly shown. Furthermore, the level of nitrogen 

 equilibrium on a diet with very low nitrogen and the normal calories 

 for weight maintenance should be established and carefully explored. 

 For all practical purposes, however, it is clear that the so-called low- 

 protein diet is perfectly justifiable as a war measure and in all prob- 

 abihty is a logical procedure that can not be accompanied with any 

 untoward effects, even by long-continued practice. Just what this 

 level should be remains to be demonstrated. 



Our evidence seems to show that, at least with American young 

 men, the nitrogen excretion in urine is much lower than has been com- 

 monly supposed. WTiether this speaks for a nitrogen metabohsm that 

 has always existed, or whether it is due to the fact that the agitation 

 for low protein has been gradually impressing itself upon the American 

 dietetic habits, we can not state. A nitrogen excretion with normal 

 men of 9 grams of nitrogen, i. e., 0.15 gram per kilogram of body-weight, 

 is a minimum level certainly well above any danger-line. 



We may say, in summarizing, that protein curtailment is an assured 

 and physiologically sound procedure, and a reduction in calories is 

 possible for long periods, but definite and significant disturbances of 

 blood composition, normal sex expression, and neuro-muscular effi- 

 ciency, and the appearance of mental and physical unrest are deterrent 

 factors in too sweeping generahzations as to the minimum calories 

 being synonymous with an optimum level. 



