A NORMAL DIET 403 



one gram more or 6.69 grams per day. Similar experiments on his friends 

 and associates gave similar results. The body weight fell slightly and then 

 remained stationary. For long periods the nitrogen in the urine remained 

 at a fairly constant low level, which was not so low, however, except with 

 Mendel, as it was with CKittenden. The average for all, including Chitten- 

 den, was 0.117 gram nitrogen per kilo per day or the equivalent of 0.74 

 gram metabolized protein per kilo per day. 



Experiments in which the nitrogen of the food, as well as that of the 

 urine and feces, was determined gave similar results. The energy con- 

 tent of the food was not determined by analysis but was calculated from the 

 results of published analyses. This involved a considerable degree of error, 

 with such complex mixtures as were here employed. 



In calculating the nitrogen balance, the nitrogen of the perspiration 

 was not included. With men engaged in sedentary occupations, the 

 amount of this was probably not great but it may very well have been 

 large enough in May and June to have wiped out the apparent positive 

 nitrogen balance (0.38 and 0.35 gm., respectively) in the second experi- 

 ments with Mendel and Beers and to have increased the nitrogen loss in 

 the corresponding experiment with Chittenden and Underbill. Moreover, 

 the small gain of nitrogen, even if entirely real, is none too large when it 

 is remembered that in other similar periods there was a greater loss. 

 Taking all nine experiments together there was an average loss of 0.329 

 gram nitrogen per man per day, with an intake of 0.125 gram nitrogen 

 and 32.0 calories per kilo per day. Practically the same values, 0.133 

 gram nitrogen and 32.4 calories, were obtained in the four experiments 

 with positive nitrogen balance. For a man of 70 kilos, these values would 

 become 58 grams protein and 2338 calories. 



Eight athletes were under observation for five months and during the 

 last two months of this period the average daily nitrogen excretion in 

 the urine was 0.127 gram per kilo. Seven of these subjects were used in 

 a seven day metabolism experiment. Considering all the results, there 

 was an average daily loss of 0.06 gram nitrogen (not including that in 

 the perspiration) per man upon an average daily intake of 0.147 gram 

 nitrogen and 38.4 calories per kilo. Considering only the four experi- 

 ments in which there was a positive nitrogen balance, the values were 

 0.158 gram nitrogen and 41.4 calories per kilo'. For a man of 70 kilos, 

 these would correspond to 69 grams protein and 2898 calories. It is 

 interesting to note that the ratio of nitrogen : calories was lower in the food 

 of the athletes than it was in that of the teachers. Notwithstanding the 

 fact that these athletes had previously been accustomed to a high protein 

 diet, they suffered no ill effect other than a slight loss in weight which may 

 even have been advantageous and continued to increase their muscular 

 strength, as measured by appropriate tests. 



A detail of soldiers of the Medical Department of the United States 



