A NORMAL DIET 407 



rhubarb or strawberries to the food led to an increase in the fecal nitro- 

 gen greater than the total nitrogen of the added food. In this manner, 

 these additions served to reduce the amount of what Hindhede regarded 

 as "digestible protein," which he calculated from the difference between 

 the nitrogen of the food and that of the feces. In this manner Hindhede 

 was able to arrive at extraordinarily low figures for protein metabolism. 

 But as pointed out on page 369, this procedure may not be justified and 

 in the present discussion of Hindhede's results, the nitrogen of the food 

 will be considered. 



The lowest value for nitrogen intake, with maintenance of equilib- 

 rium, was obtained on the potato diet with 7.59 grams nitrogen or about 

 47 grams of protein for a man of 70.7 kilos. (The slightly lower value, 

 6.98 grams nitrogen or 44 grams protein, obtained in period E, was prob- 

 ably accompanied by a loss of nitrogen for the apparent gain of 0.2 gram 

 nitrogen per day was scarcely sufficient to account for the loss in perspira- 

 tion in the case of a man engaged in the hard work Fr. Madsen was then 

 performing.) This appears to be the lowest protein intake, accompanied 

 by a positive nitrogen balance, that has been recorded. 



The analytical results reported by Hindhede cover a very consider- 

 able period, two years in the case of Fr. Madsen. It is difficult to ex- 

 tend quantitative observations over even so long a time as that and any 

 of longer duration are almost impossible. But it should be remembered 

 that Hindhede's subjects, particularly the two Madsens, were accustomed 

 to a very low level of protein metabolism and were, nevertheless, healthy, 

 vigorous men, well above the average in muscular development and en- 

 durance. Hindhede's own customary diet contained only 10.34 grams 

 nitrogen or 64.6 grams protein per day and that of his family, which 

 included children, only 75.7 grams per man. 



The energy content of the food consumed by Hindhede's subjects 

 appears to be rather high. It is possible that this low level of protein me- 

 tabolism could be attained only at the cost of a large carbohydrate metabol- 

 ism. However that may be, it is noteworthy that the very low protein me- 

 tabolism observed in the case of the Madsens necessitated a very monotonous 

 and limited dietary. Hindhede himself called attention to the difficulty of 

 making a potato diet palatable or even endurable for any considerable 

 period. It required the greatest care in the selection and preparation of 

 the potatoes. On the bread diets, large quantities of sugar were required 

 in order to maintain the energy yield of the foo'd while keeping the pro- 

 tein content low. 



As a matter of fact, unless unusual reliance be placed upon more or 

 less purified foods such as starch, sugars and fats, it is nearly impossible 

 to obtain 3000 calories without securing at the same time about 70 grains 

 of protein or one gram per kilo. Reference to Table IV shows that this 

 level is reached by all the dietaries reported, if only the energy content 



