The last of March, a third nitrogen balance was tried on a slightly
lowered nitrogen intake and with a slight increase in the fuel value of
the daily food. In this period of five days, March 28 to April 1, the
nitrogen taken in per day averaged 8.62 grams, or nearly one gram per day
less than in the preceding period. The fuel value of the food averaged
2840 calories per day, or about 300 calories more than in the preceding
period.
The daily diet, with its content of nitrogen, etc., is detailed for each
day under Oakman. Any deviation from this diet in the cases of the other
men is indicated on the accompanying balance-sheets.
The results obtained in this balance period indicate that the lowest
level had been practically reached, at least under the conditions of
body-weight, food, and work prevailing. Cohn, Fritz, and Broyles showed
a distinct positive balance. Steltz and Loewenthal were practically
in equilibrium, the deviation being within the limits of error. The
remaining six men showed a minus balance, although in no case was it very
marked.
It is interesting to note in this connection that the average daily
output of nitrogen through the urine for this five days’ period (Oakman’s
case) amounted to 7.04 grams, being 0.2 gram less per day than in the
preceding period. This figure for nitrogen in the urine means the
metabolism daily of 44 grams of proteid.
Undoubtedly, the rate of proteid metabolism for these men could have been
lowered considerably beyond the present level by increasing largely the
intake of carbohydrates and fats, but it has been the intent throughout
all of these experiments to learn the minimal proteid requirement
under conditions precluding the use of any excess of non-nitrogenous
foods; also, to study the effect of a general physiological economy
in nutrition, with a view to ascertaining the real necessities of the
body for both proteid and non-proteid foods with maintenance of bodily
strength and vigor. Hence, we may again emphasize the fact that the low
proteid metabolism maintained by all these men throughout the period
of the experiment, with establishment of nitrogenous equilibrium on a
consumption of proteid or albuminous food averaging one-half the amount
ordinarily specified as the daily requirement of the healthy man, has
been accomplished with even less total food—fats and carbohydrates—than
the ordinary standards call for, _i. e._, considerably less than 3000
calories per day in fuel value.