116 THE PROTEIN ELEMENT IN NUTRITION 



quantities of food consumed by Chittenden during the days of 

 the nitrogen balance. The dietaries are recorded in weights for 

 cooked food, but the weight in the dry condition could not have 

 reached more than 12 to 14 ounces daily, of which a very large 

 proportion consisted of potatoes and lettuce-orange salad. With 

 so large a quantity of vegetable material entering into the diet 

 during the days of observation, it is all the more noticeable how 

 very small the loss of nitrogen in the fseces proved to be. The 

 very small quantities of food taken during the days of observation 

 may be partly accounted for by the subject unconsciously living 

 more abstemiously than usual, or perhaps choosing foodstuffs 

 deficient in both protein and potential energy. That this ex- 

 planation is not improbable is brought out in the following 

 summary of the diet for June 23, 1904 :* 



Nitrogen Value. 



Total weight of cooked diet, excluding fluids drunk . . 854 grins. 6*622 grms. 

 Weight of potatoes, strawberries, and lettuce -orange 



salad 445 0-957 



That is, over half the gross weight of the cooked ration is 

 made up of vegetable material which, as a matter of fact, is 

 largely water, and which only offers one-seventh part of the total 

 nitrogen of the diet. The potential energy of these materials is 

 similarly deficient. By the choice of such foods, whilst there 

 may be the feeling of satisfaction after a meal, the nitrogen and 

 energy value can be brought to a very low level. It is quite 

 possible, as Benedict*)- has shown in the case of a subject living on 

 about 1,600 calories, that the body was not in energy equilibrium, 

 but that there was an oxidation of the body fat with a reten- 

 tion of water, the body weight thus remaining fairly constant. 



Chittenden experimented with three groups of subjects : the 

 first consisted of professional men doing a minimum amount of 

 muscular work ; the second was composed of volunteers from the 

 Army Hospital Corps who took a moderate amount of exercise ; 

 while the third group was made up of students engaged in active 

 athletics . The study by Chittenden on himself referred to above is 

 by far the most remarkable of those carried out on professional men. 



The studies with thirteen soldiers from the Hospital Corps 

 gave results very similar to those obtained with the professional 

 men of the first group. The soldiers were able to maintain them- 

 selves in nitrogenous equilibrium on a dietary of poor protein 



* Chittenden., " Physiological Economy in Nutrition," p. 43. 

 f Benedict and Carpenter : " Metabolism and Energy Transformations of 

 Healthy Man during Rest." 



