Physiological economy in nutrition, with special reference to the minimal proteid requirement of the healthy man

Chapter I: Experiments with Professional Men (3)

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Dr. Frank P. Underhill, instructor in physiological chemistry in the Sheffield Scientific School, is another subject of experiment who volunteered to study on himself the effects of a lowered proteid intake. Prior to the experiment he was in the habit of eliminating from 16 to 16.5 grams of nitrogen per day through the kidneys, representing the usual 105 grams of proteid food metabolized.

Dr. Underhill, at the beginning of the experiment, July 1, 1903, was twenty-six years of age and weighed 67.6 kilos. For a period of two weeks, from July 14 to August 2, he gradually reduced the intake of proteid food as well as the total amount of food consumed, doing this in part by diminishing the quantity eaten at breakfast, and in smaller measure at the two other meals of the day. During this period of two weeks, the urine and fæces were analyzed with the results shown in the accompanying table. Regarding the extent of proteid metabolism, it will be seen that the nitrogen content of the urine fell from 14.28 grams per day down to 5 to 6 grams per day. Having reached this level, the subject maintained it throughout the summer of 1903, occasional analyses being made to demonstrate the level of nitrogen excretion.

+-------+-------+-----------------------+-----------------------+-------+
| | Body- | Urine. | Fæces. | Total |
| Date. |weight.+-------+-----+---------+------+------+---------+ Nitro-|
| | |Volume.| Sp. |Nitrogen.|Moist.| Dry. |Nitrogen.| gen. |
| | | | Gr. | | | | | |
+-------+-------+-------+-----+---------+------+------+---------+-------+
| 1903. | | c.c. | | grams. |grams.|grams.| grams. | grams.|
|July 14| 67.6 | 1300 | 1018| 14.28 | 156.0| 30.5 | 1.59 | 15.8 |
| 15| 67.6 | 1095 | 1020| 11.72 | 70.0| 17.0 | 0.80 | 12.52 |
| 16| 67.1 | 860 | 1021| 11.72 | 182.5| 44.5 | 2.12 | 13.84 |
| 17| 66.9 | 675 | 1022| 9.39 | 134.0| 43.0 | 2.05 | 11.44 |
| 18| 66.3 | 865 | 1021| 10.45 | 57.5| 20.0 | 0.95 | 11.40 |
| 19| 65.7 | 785 | 1021| 10.34 | 170.0| 41.0 | 1.95 | 12.29 |
| 20| 65.7 | 740 | 1024| 10.34 | 76.0| 35.0 | 1.66 | 12.00 |
| 21| 65.7 | 910 | 1017| 11.61 | 96.0| 32.0 | 1.52 | 13.13 |
| 22| 65.7 | 900 | 1013| 9.50 | 56.0| 31.0 | 1.75 | 11.25 |
| 23| 65.3 | 600 | 1017| 8.65 | 41.0| 14.0 | 0.79 | 9.35 |
| 24| 65.0 | 640 | 1013| 6.65 | 151.0| 33.0 | 1.86 | 8.51 |
| 25| 65.3 | 690 | 1012| 6.01 | 86.0| 29.0 | 1.63 | 7.64 |
| 26| 65.3 | 410 | 1023| 6.65 | 57.0| 19.0 | 1.06 | 7.71 |
| 27| 65.7 | 530 | 1017| 6.75 | 202.0| 33.0 | 1.86 | 8.61 |
| 28| 65.7 | 610 | 1013| 5.49 | 155.0| 26.0 | 1.46 | 6.95 |
| 29| 66.4 | 620 | 1017| 5.96 | 121.0| 26.0 | 1.46 | 7.42 |
| 30| 66.3 | 700 | 1016| 5.80 | 233.0| 48.0 | 2.71 | 8.51 |
| 31| 65.8 | 1265 | 1010| 6.70 | 211.0| 36.0 | 2.03 | 8.73 |
| Aug. 1| 65.3 | 1240 | 1009| 6.23 | 172.0| 23.0 | 1.29 | 7.52 |
| 2| 65.3 | 760 | 1016| 6.75 | 214.0| 27.0 | 1.42 | 8.17 |
| 11| 65.3 | 500 | 1017| 6.44 | 152.0| 22.0 | 1.34 | 7.78 |
| 12| 65.3 | 405 | 1024| 6.86 | 70.0| 15.0 | 0.91 | 7.77 |
| 13| 65.3 | 540 | 1019| 6.23 | 90.0| 10.0 | 0.61 | 6.84 |
+-------+-------+-------+-----+---------+------+------+---------+-------+

In connection with the accompanying table of results, attention is called to the composition of the fæces with special reference to their content of nitrogen. The point to be emphasized is the gradual increase in the percentage content of fæcal nitrogen, associated with the changed diet and the general diminution of food intake. This is well illustrated by the following figures, giving the percentage of nitrogen in the dry fæces for the three periods of July 14-21, July 22-30, and August 11-13:

July 14-21, 4.77 per cent Nitrogen
July 22-30, 5.65 ” ” ”
Aug. 11-13, 6.11 ” ” ”

The diminished amount of fæcal discharge means naturally not only a smaller intake of food, but implies also a greater utilization of the food ingested, and as a result the increased percentage of nitrogen in the discharges shows itself because of the relatively larger preponderance of nitrogenous secretions from the intestinal tract.

The latter part of September, 1903, Dr. Underhill attempted to return to his original methods of living, but found difficulty in consuming the daily quantities of food he had formerly been in the habit of taking. From October 11 to October 25, 1903, however, he raised the consumption of proteid food to such a degree that the nitrogen excretion through the urine averaged from 10 to 12 grams per day. After this date he fell back to the lower proteid intake, and from that period to June 23, 1904, he maintained a low level of proteid metabolism without detriment to his bodily vigor, and, as he believes, with a distinct betterment.

The following tables of results extending from October 11, 1903, to June 23, 1904, show the data collected.

UNDERHILL.

+-----------+-------+--------------------------------------------------+
| | | |
| | | Urine. |
| | | |
| Date. | Body- +-------+------+-----------+-----------+-----------+
| |weight.|Volume.| Sp. | Nitrogen. | Uric Acid.| P₂O₅. |
| | | 24 | Gr. | | | |
| | |hours. | | | | |
+-----------+-------+-------+------+-----------+-----------+-----------+
| 1903 | kilos | c.c. | | grams | gram | grams |
| | | | | | | |
| Oct. 11 | 65.4 | 1300 | 1015 | 10.37 | 0.611 | 1.72 |
| 12 | | 700 | 1022 | 9.07 | | |
| 13 | | 1050 | 1022 | 12.35 | 0.820 | 2.15 |
| 14 | | 1400 | 1017 | 12.01 | | |
| 15 | | 870 | 1020 | 11.48 | 0.671 | 1.76 |
| 16 | | 1165 | 1013 | 12.09 | | |
| 17 | | 840 | 1020 | 11.24 | | |
| 18 | | 1150 | 1017 | 10.00 | 0.613 | 1.77 |
| 19 | | 678 | 1022 | 7.79 | | |
| 20 | | 1165 | 1018 | 10.76 | 0.603 | 1.60 |
| 21 | | 1460 | 1017 | 11.91 | | |
| 22 | | 950 | 1019 | 10.71 | 0.643 | 1.73 |
| 23 | | 1165 | 1017 | 12.82 | | |
| 24 | 65.4 | 850 | 1025 | 12.49 | | |
| 25 | | 850 | 1022 | 11.07 | 0.645 | 1.76 |
| 26 | | 1025 | 1018 |⎫ | | |
| 27 | | 775 | 1018 |⎪ | | |
| 28 | | 1140 | 1015 |⎬ 8.31 | 0.465 | 1.18 |
| 29 | | 765 | 1020 |⎪ daily | daily | daily |
| 30 | | 860 | 1019 |⎪ average | average | average |
| 31 | | 1150 | 1015 |⎭ | | |
| Nov. 1 | | 750 | 1020 |⎫ | | |
| 2 | | 675 | 1022 |⎪ | | |
| 3 | | 955 | 1014 |⎪ | | |
| 4 | | 1270 | 1012 |⎬ 7.91 | 0.469 | 1.30 |
| 5 | | 885 | 1015 |⎪ | | |
| 6 | | 770 | 1020 |⎪ | | |
| 7 | | 860 | 1021 |⎭ | | |
| 8 | | 775 | 1020 |⎫ | | |
| 9 | | 890 | 1018 |⎪ | | |
| 10 | | 1070 | 1018 |⎪ | | |
| 11 | | 755 | 1020 |⎬ 7.86 | 0.537 | 1.40 |
| 12 | | 950 | 1023 |⎪ | | |
| 13 | | 1100 | 1017 |⎪ | | |
| 14 | | 980 | 1015 |⎪ | | |
| 15 | | 630 | 1020 |⎭ | | |
| 16 | 65.0 | 700 | 1020 |⎫ | | |
| 17 | | 1000 | 1015 |⎪ | | |
| 18 | | 940 | 1018 |⎪ | | |
| 19 | | 770 | 1023 |⎬ 7.82 | 0.467 | 1.49 |
| 20 | | 770 | 1025 |⎪ | | |
| 21 | | 790 | 1020 |⎪ | | |
| 22 | | 770 | 1021 |⎭ | | |
| 23 | | 590 | 1025 |⎫ | | |
| 27 | | 710 | 1024 |⎬ 8.55 | 0.476 | 1.67 |
| 28 | | 1080 | 1017 |⎪ | | |
| 29 | | 760 | 1019 |⎭ | | |
| 30 | | 870 | 1018 |⎫ | | |
| Dec. 1 | | 860 | 1017 |⎪ | | |
| 2 | | 1120 | 1015 |⎪ | | |
| 3 | | 1450 | 1009 |⎬ 7.72 | 0.506 | 1.43 |
| 4 | | 720 | 1019 |⎪ | | |
| 5 | | 720 | 1019 |⎪ | | |
| 6 | | 510 | 1027 |⎭ | | |
| 7 | 65.1 | 700 | 1018 |⎫ | | |
| 8 | | 650 | 1018 |⎪ | | |
| 9 | | 860 | 1013 |⎪ | | |
| 10 | | 975 | 1020 |⎬ 7.36 | 0.474 | 1.44 |
| 11 | | 800 | 1021 |⎪ | | |
| 12 | | 830 | 1018 |⎪ | | |
| 13 | | 750 | 1019 |⎭ | | |
| 14 | | 860 | 1018 |⎫ | | |
| 15 | | 870 | 1019 |⎪ | | |
| 16 | | 880 | 1015 |⎪ | | |
| 17 | | 820 | |⎬ 8.11 | 0.497 | 1.35 |
| 18 | | 760 | 1021 |⎪ | | |
| 19 | | 860 | 1017 |⎪ | | |
| 20 | | 520 | 1023 |⎭ | | |
| 21 | | 1200 | 1014 |⎫ 7.18 | | 1.05 |
| 22 | 65.0 | 510 | 1025 |⎭ | | |
| 23 | | 650 | |⎫ | | |
| 24 | | 670 | |⎪ | | |
| 25 | | 500 | |⎬ 6.70 | 0.356 | 0.97 |
| 26 | | 550 | |⎪ | | |
| 27 | | 850 | |⎭ | | |
| 28 | 65.2 | 930 | |⎫ | | |
| 29 | | 1200 | |⎪ | | |
| 30 | | 750 | |⎪ | | |
| 31 | | 1280 | |⎬ 8.70 | 0.626 | 1.21 |
| Jan. 1 | | 750 | |⎪ | | |
| 2 | | 750 | |⎪ | | |
| 3 | | 870 | |⎪ | | |
| 4 | | 1230 | |⎭ | | |
| 5 | | 720 | 1023 |⎫ | | |
| 6 | | 960 | 1020 |⎪ | | |
| 7 | | 760 | 1022 |⎪ | | |
| 8 | | 1000 | 1017 |⎬ 8.23 | 0.530 | 1.24 |
| 9 | | 720 | 1025 |⎪ | | |
| 10 | 65.1 | 730 | 1021 |⎭ | | |
| 11 | | 700 | 1016 |⎫ | | |
| 12 | | 650 | 1020 |⎪ | | |
| 13 | | 700 | 1024 |⎪ | | |
| 14 | | 660 | 1025 |⎬ 7.74 | 0.618 | 1.20 |
| 15 | | 610 | 1025 |⎪ | | |
| 16 | | 710 | 1024 |⎪ | | |
| 17 | | 660 | 1022 |⎭ | | |
| 18 | | 770 | 1016 |⎫ | | |
| 19 | 64.8 | 700 | 1022 |⎪ | | |
| 20 | | 1130 | 1018 |⎪ | | |
| 21 | | 830 | 1020 |⎬ 7.80 | 0.705 | 1.14 |
| 22 | | 600 | 1019 |⎪ | | |
| 23 | | 480 | 1021 |⎪ | | |
| 24 | | 750 | 1019 |⎭ | | |
| 25 | | 680 | 1020 |⎫ | | |
| 26 | | 800 | 1018 |⎪ | | |
| 27 | | 800 | 1020 |⎪ | | |
| 28 | | 700 | 1020 |⎬ 6.85 | 0.500 | 1.07 |
| 29 | 64.4 | 1010 | 1014 |⎪ | | |
| 30 | | 980 | 1018 |⎭ | | |
| 31 | | 820 | 1015 |⎫ | | |
| Feb. 1 | | 990 | 1015 |⎪ | | |
| 2 | | 660 | 1020 |⎪ | | |
| 3 | 64.4 | 1060 | 1015 |⎪ | | |
| 4 | | 980 | 1017 |⎬ 7.98 | 0.535 | 1.24 |
| 5 | | 970 | 1014 |⎪ | | |
| 6 | | 790 | 1019 |⎪ | | |
| 7 | | 1120 | 1015 |⎭ | | |
| 8 | | 715 | 1021 | 8.11 | | |
| 9 | 64.4 | 1225 | 1014 | 7.49 | 0.450 | |
| 10 | 64.4 | 770 | 1018 | 6.14 | 0.505 | |
| 11 | 64.5 | 715 | 1022 | 8.02 | 0.568 | |
| 12 | | 850 | 1021 | 8.82 | 0.539 | |
| 13 | | 490 | 1028 | 7.17 | 0.505 | |
| 14 | 64.4 | 795 | 1020 | 7.73 | 0.543 | |
| 15 | | 780 | 1021 |⎫ | | |
| 16 | | 920 | 1023 |⎪ | | |
| 17 | | 660 | 1021 |⎪ | | |
| 18 | | 640 | 1027 |⎬ 8.27 | 0.558 | |
| 19 | | 730 | 1023 |⎪ | | |
| 20 | | 840 | 1027 |⎪ | | |
| 21 | | 700 | 1018 |⎭ | | |
| 22 | | 440 | 1025 |⎫ | | |
| 23 | | 600 | 1023 |⎪ | | |
| 24 | | 750 | 1022 |⎪ | | |
| 25 | | 830 | 1017 |⎬ 7.47 | 0.556 | |
| 26 | 64.0 | 870 | 1021 |⎪ | | |
| 27 | | 910 | 1015 |⎪ | | |
| 28 | | 950 | 1014 |⎭ | | |
| 29 | | 600 | 1021 |⎫ | | |
| Mar. 1 | | 680 | 1021 |⎪ | | |
| 2 | | 1120 | 1011 |⎪ | | |
| 3 | | 640 | 1021 |⎬ 7.15 | 0.526 | |
| 4 | | 1080 | 1016 |⎪ | | |
| 5 | | 1220 | 1034 |⎪ | | |
| 6 | | 890 | 1015 |⎭ | | |
| 7 | | 1000 | 1014 |⎫ | | |
| 8 | | 650 | 1020 |⎪ | | |
| 9 | | 750 | 1020 |⎪ | | |
| 10 | | 850 | 1018 |⎬ 8.18 | 0.682 | |
| 11 | | 950 | 1014 |⎪ | | |
| 12 | | 1000 | 1016 |⎪ | | |
| 13 | 64.2 | 860 | 1019 |⎭ | | |
| 14 | | 840 | 1020 |⎫ | | |
| 15 | | 920 | 1016 |⎪ | | |
| 16 | | 750 | 1020 |⎪ | | |
| 17 | | 820 | 1017 |⎬ 7.83 | 0.540 | |
| 18 | | 1220 | 1012 |⎪ | | |
| 19 | | 920 | 1015 |⎪ | | |
| 20 | | 700 | 1022 |⎭ | | |
| 21 | | 900 | 1015 |⎫ | | |
| 22 | | 980 | 1013 |⎪ | | |
| 23 | | 990 | 1014 |⎪ | | |
| 24 | | 750 | 1020 |⎬ 8.04 | 0.733 | |
| 25 | | 820 | 1017 |⎪ | | |
| 26 | | 700 | 1021 |⎪ | | |
| 27 | | 910 | 1020 |⎭ | | |
| 28 | | 930 | 1017 | | | |
| 30 | | 900 | 1020 | | | |
| 31 | | 450 | |⎫ | | |
| Apr. 1 | | 500 | |⎪ | | |
| 2 | | 420 | |⎪ | | |
| 3 | | 600 | |⎪ | | |
| 4 | | 950 | |⎪ | | |
| 5 | | 930 | |⎬ 7.87 | 0.530 | 1.44 |
| 6 | | 980 | |⎪ | | |
| 7 | | 600 | |⎪ | | |
| 8 | | 980 | |⎪ | | |
| 9 | | 800 | |⎪ | | |
| 10 | | 810 | |⎭ | | |
| 11 | 65.2 | 940 | 1017 |⎫ |⎫ | |
| 12 | | 710 | 1024 |⎬ 9.46 |⎪ | |
| 13 | | 750 | 1024 |⎭ |⎪ | |
| 14 | | 740 | 1020 | 7.55 |⎬ 0.496 | |
| 15 | | 590 | 1024 | 6.51 |⎪ | |
| 16 | | 900 | 1016 | 7.51 |⎪ | |
| 17 | | 1290 | 1009 | 5.11 |⎭ | |
| 18 | 65.2 | 590 | 1017 | 5.96 |⎫ | |
| 19 | | 630 | 1024 | 6.39 |⎪ | |
| 20 | | 670 | 1022 | 7.48 |⎪ | |
| 21 | | 900 | 1021 | 8.10 |⎬ 0.527 | |
| 22 | | 980 | 1017 | 7.00 |⎪ | |
| 23 | | 850 | 1019 | 7.60 |⎪ | |
| 24 | | 640 | 1023 | 7.33 |⎭ | |
| 25 | 65.0 | 600 | 1021 | 8.23 |⎫ | |
| 26 | | 610 | 1014 | 5.82 |⎪ | |
| 27 | | 600 | 1023 | 7.27 |⎪ | |
| 28 | | 970 | 1015 | 7.05 |⎬ 0.490 | |
| 29 | | 795 | 1017 | 5.91 |⎪ | |
| 30 | | 700 | 1021 | 6.80 |⎪ | |
| May 1 | | 795 | 1016 | 5.72 |⎭ | |
| 2 | 65.2 | 860 | 1017 | 6.50 |⎫ | |
| 3 | | 1120 | 1016 | 6.92 |⎪ | |
| 4 | | 1090 | 1015 | 6.54 |⎪ | |
| 5 | | 580 | 1021 | 5.92 |⎬ 0.344 | |
| 6 | | 700 | 1020 | 7.29 |⎪ | |
| 7 | | 895 | 1017 | 8.97 |⎪ | |
| 8 | | 800 | 1016 | 7.30 |⎭ | |
| 9 | 65.2 | 895 | 1019 | 6.28 |⎫ | |
| 10 | | 850 | 1019 | 6.27 |⎪ | |
| 11 | | 960 | 1019 | 7.26 |⎪ | |
| 12 | | 690 | 1022 | 6.29 |⎬ 0.416 | |
| 13 | | 990 | 1017 | 7.96 |⎪ | |
| 14 | | 690 | 1022 | 7.21 |⎪ | |
| 15 | | 900 | 1015 | 6.15 |⎭ | |
| 16 | 65.1 | 945 | 1014 | 5.10 |⎫ | |
| 17 | | 1090 | 1016 | 6.15 |⎪ | |
| 18 | | 620 | 1020 | 5.21 |⎪ | |
| 19 | | 1110 | 1015 | 6.53 |⎪ | |
| 20 | | 895 | 1016 | 6.12 |⎬ 0.364 | |
| 21 | | 810 | 1019 | 6.95 |⎪ | |
| 22 | | 1110 | 1016 | 8.72 |⎪ | |
| 23 | 65.0 | 685 | 1020 | 7.07 |⎪ | |
| 24 | | 560 | 1021 | 6.78 |⎭ | |
| 25 | | 1090 | 1010 | 6.02 |⎫ | |
| 26 | | 610 | 1017 | 5.97 |⎪ | |
| 27 | | 790 | 1016 | 6.83 |⎪ | |
| 28 | | 1100 | 1014 | 7.65 |⎬ 0.420 | |
| 29 | | 650 | 1021 | 6.12 |⎪ | |
| 30 | 65.0 | 630 | 1021 | 5.21 |⎪ | |
| 31 | | 660 | 1018 | 5.07 |⎭ | |
| June 1 | 65.1 | 920 | 1014 | 5.96 | | |
| 2 | 65.1 | 800 | 1013 | 5.81 | | |
| 3 | 65.0 | 950 | 1014 | 7.30 | | |
| 4 | | 790 | 1015 | 6.78 | | |
| 5 | | 780 | 1020 | 8.28 | | |
| 6 | 65.1 | 890 | 1015 | 6.89 | | |
| 7 | | 720 | 1017 | 5.87 | | |
| 8 | | 950 | 1015 | 5.93 | | |
| 9 | | 1060 | 1014 | 4.96 | | |
| 10 | | 940 | 1017 | 5.92 | | |
| 11 | | 1050 | 1019 | 7.62 | | |
| 12 | | 1000 | 1017 | 6.66 | | |
| 13 | | 890 | 1021 | 7.26 | | |
| 14 | | 1340 | 1016 | 6.91 | | |
| 15 | | 1190 | 1015 | 6.86 | | |
| 16 | | 720 | 1025 | 7.99 | | |
| 17 | 65.2 | 800 | 1017 | 7.25 | | |
| 18 | | 820 | 1018 | 6.99 | | |
| 19 | | 920 | 1014 | 6.18 | | |
| 20 | | 890 | 1015 | 6.03 | | |
| 21 | | 900 | 1016 | 6.37 | | |
| 22 | | 760 | 1018 | 6.79 | | |
| 23 | | 630 | 1020 | 6.06 | | |
+-----------+-------+-------+------+-----------+-----------+-----------+
|Daily average from | | | | | |
| Oct. 26, 1903 | 833 | 1018 | 7.43 | 0.516 | 1.28 |
+-------------------+-------+------+-----------+-----------+-----------+

It will be seen by a study of the analytical data that Dr. Underhill had an average daily excretion of nitrogen through the kidneys from October 26, 1903, to June 23, 1904, of 7.43 grams. From October 26 to April 13, a period of nearly six months, the average daily excretion was 7.81 grams of nitrogen, while from the latter date to June 23 the average daily excretion amounted to 6.68 grams of nitrogen. Taking the body-weight at 65 kilos, the lower nitrogen figure would mean a metabolism of 0.102 gram of nitrogen per kilo of body-weight, closely akin to the figures obtained with the two preceding subjects.

An excretion of 6.68 grams of nitrogen corresponds to the metabolism of 41.75 grams of proteid matter, while the excretion of 7.43 grams of nitrogen implies the metabolism of 46.4 grams of proteid, being less than one-half the ordinarily accepted requirement for the healthy adult.

During this long period of eight months the body-weight was stationary, carrying with it the assumption that the body was in a condition of nitrogen equilibrium. It should be emphasized in connection with Dr. Underhill’s case, that throughout the entire period of eight months, and more, there was perfect freedom in the choice of food. Further, it will be noticed by a study of the dietary made use of in the balance experiments that Dr. Underhill did not reduce his nitrogen intake by any exclusion of meat. He practically made use of his ordinary diet, such as he had always been accustomed to, but with a decided diminution of the amount of proteid food, accompanied by a gradual reduction in the total amount of food consumed each day. His diet, therefore, was in no sense a vegetable diet. Meat was conspicuous in his daily food, but naturally in reduced quantities.

On February 9 a nitrogen balance was attempted, in which a careful comparison of the nitrogen content of all intake and output was made for a period of six days. By a study of the results of this balance period, shown in the accompanying tables, it will be noticed that not only was there no deficiency of nitrogen, but the body was laying on nitrogen at the rate of 0.158 gram per day. Further, it will be observed that the fuel value of the food per day averaged only a little over 2000 calories. Yet this amount of food, with its comparatively low fuel value, carried with it only 8.83 grams of nitrogen per day. Upon this quantity of food the body was able to maintain itself, with a little nitrogen to spare and with sufficient fuel value in the food to supply all the energy required for muscular contraction, mental effort, and the maintenance of body temperature.

_Tuesday, February 9, 1904._

Breakfast.—Bread 22 grams, tea 146 grams.

Lunch.—Macaroni 129 grams, fried sweet potato 85.5 grams, bread 59 grams, butter 15 grams, fig cake with wine sauce 115 grams, sugar 15 grams, coffee 210 grams.

Dinner.—Bread 27.9 grams, beef 48 grams, potato 207.5 grams, butter 19 grams, pie 272 grams, coffee 210 grams, sugar 10 grams.

Food. Grams. Per cent Nitrogen. Total Nitrogen.

Bread 22 + 59 + 27.9 = 108.9 × 1.61 = 1.753 grams.
Tea 146.0 × 0.018 = 0.026
Macaroni 129.0 × 0.87 = 1.122
Sweet potato 85.5 × 0.28 = 0.240
Butter 15 + 19 = 34.0 × 0.088 = 0.030
Fig cake 115.0 × 0.69 = 0.793
Sugar 15 + 10 = 25.0 × 0.00 = 0.000
Coffee (lunch) 210.0 × 0.09 = 0.207
Beef 48.0 × 2.64 = 1.267
Potatoes 207.5 × 0.36 = 0.747
Pie 272.0 × 0.49 = 1.332
Coffee (dinner) 210.0 × 0.15 = 0.315
------
Total nitrogen in food 7.832 grams.
Total nitrogen in urine 7.490

Fuel value of the food 2232 calories.

_Wednesday, February 10, 1904._

Breakfast.—Bread 33 grams, tea 146 grams.

Lunch.—Bread 71 grams, butter 10.5 grams, apple fritters 119 grams, coffee 210 grams, sugar 21 grams.

Dinner.—Roast pork 80 grams, bread 55.7 grams, butter 27.8 grams, cranberry sauce 150 grams, coffee 210 grams, sugar 21 grams.

Food. Grams. Per cent Nitrogen. Total Nitrogen.

Bread 33 + 71 + 55.7 = 159.7 × 1.65 = 2.635 grams.
Tea 146.0 × 0.075 = 0.109
Butter 10.5 + 27.8 = 38.3 × 0.088 = 0.033
Apple fritters 119.0 × 0.45 = 0.535
Coffee (lunch) 210.0 × 0.11 = 0.231
Sugar 21 + 21 = 42.0 × 0.00 = 0.000
Roast pork 80.0 × 4.80 = 3.840
Cranberry sauce 150.0 × 0.04 = 0.060
Coffee (dinner) 210.0 × 0.11 = 0.231
------
Total nitrogen in food 7.674 grams.
Total nitrogen in urine 6.140

Fuel value of the food 1694 calories.

_Thursday, February 11, 1904._

Breakfast.—Bread 38.7 grams, tea 146 grams.

Lunch.—Bread 97.5 grams, butter 31.5 grams, sweet potato 108.7 grams, spaghetti 82.5 grams, peaches 89.4 grams, coffee 210 grams, sugar 21 grams.

Dinner.—Bread 75 grams, butter 21.5 grams, roast beef 116 grams, lemon pie 188.5 grams, coffee 210 grams, sugar 21 grams.

Food. Grams. Per cent Nitrogen. Total Nitrogen.

Bread 38.7 + 97.5 + 75 = 211.2 × 1.75 = 3.696 grams.
Tea 146.0 × 0.084 = 0.122
Butter 31.5 + 21.5 = 53.0 × 0.088 = 0.046
Sweet potato 108.7 × 0.31 = 0.336
Spaghetti 82.5 × 0.47 = 0.387
Peaches 89.4 × 0.09 = 0.080
Coffee (lunch) 210.0 × 0.096 = 0.201
Sugar 21 + 21 = 42.0 × 0.00 = 0.000
Roast beef 116.0 × 3.00 = 3.480
Lemon pie 188.5 × 0.61 = 1.149
Coffee (dinner) 210.0 × 0.13 = 0.273
------
Total nitrogen in food 9.770 grams.
Total nitrogen in urine 8.020

Fuel value of the food 2334 calories.

_Friday, February 12, 1904._

Breakfast.—Bread 34 grams, tea 146 grams.

Lunch.—Bread 42 grams, butter 20 grams, codfish cake 72 grams, potato 100 grams, custard 100 grams, coffee 210 grams, sugar 21 grams.

Dinner.—Bread 46 grams, butter 25.5 grams, veal 53 grams, potato 75 grams, lima beans 50 grams, apple dumpling 120 grams, coffee 210 grams, sugar 21 grams.

Food. Grams. Per cent Nitrogen. Total Nitrogen.

Bread 34 + 42 + 46 = 122.0 × 1.71 = 2.086 grams.
Tea 146.0 × 0.045 = 0.065
Butter 20 + 25.5 = 45.5 × 0.088 = 0.040
Codfish cake 72.0 × 1.57 = 1.130
Potato 100.0 × 0.41 = 0.410
Custard 100.0 × 0.83 = 0.830
Coffee (lunch) 210.0 × 0.078 = 0.163
Sugar 21 + 21 = 42.0 × 0.00 = 0.000
Veal 53.0 × 5.51 = 2.920
Potato 75.0 × 0.37 = 0.277
Lima beans 50.0 × 0.90 = 0.450
Apple dumpling 120.0 × 0.72 = 0.860
Coffee (dinner) 210.0 × 0.12 = 0.252
------
Total nitrogen in food 9.483 grams.
Total nitrogen in urine 8.820

Fuel value of the food 1735 calories.

_Saturday, February 13, 1904._

Breakfast.—Bread 35 grams, tea 146 grams.

Lunch.—Bread 57.5 grams, butter 28 grams, sweet potato 100 grams, coffee 210 grams, sugar 21 grams, quince 105.5 grams, apple turnovers 153 grams.

Dinner.—Bread 35.5 grams, butter 11 grams, peas 70 grams, roast beef 50 grams, pie 169 grams, coffee 210 grams, sugar 21 grams.

Food. Grams. Per cent Nitrogen. Total Nitrogen.

Bread 35 + 57.5 + 35.5 = 128.0 × 1.64 = 2.099 grams.
Tea 146.0 × 0.033 = 0.048
Butter 28 + 11 = 39.0 × 0.088 = 0.034
Sweet potato 100.0 × 0.37 = 0.370
Coffee (lunch) 210.0 × 0.15 = 0.315
Sugar 21 + 21 = 42.0 × 0.00 = 0.000
Quince 105.5 × 0.047 = 0.049
Apple turnovers 153.0 × 0.96 = 1.468
Peas 70.0 × 0.96 = 0.672
Roast beef 50.0 × 3.22 = 1.610
Pie 169.0 × 0.43 = 0.726
Coffee (dinner) 210.0 × 0.11 = 0.231
------
Total nitrogen in food 7.622 grams.
Total nitrogen in urine 7.170

Fuel value of the food 2186 calories.

_Sunday, February 14, 1904._

Breakfast.—Bread 31 grams, tea 146 grams.

Lunch.—Bread 70.5 grams, butter 29 grams, potato 123 grams, apple sauce 127.5 grams, coffee 210 grams, sugar 21 grams.

Dinner.—Bread 20.5 grams, butter 23 grams, chicken 101.5 grams, potato 80 grams, succotash 80 grams, chocolate cake 103 grams, ice cream 125.8 grams, coffee 210 grams, sugar 21 grams.

Food. Grams. Per cent Nitrogen. Total Nitrogen.

Bread 31 + 70.5 + 20.5 = 122.0 × 1.75 = 2.135 grams.
Tea 146.0 × 0.063 = 0.091
Butter 29 + 23 = 52.0 × 0.088 = 0.045
Potato 123.0 × 0.41 = 0.504
Apple sauce 127.5 × 0.029 = 0.037
Coffee (lunch) 210.0 × 0.10 = 0.210
Sugar 21 + 21 = 42.0 × 0.00 = 0.000
Chicken 101.5 × 5.08 = 5.150
Potato 80.0 × 0.37 = 0.296
Succotash 80.0 × 0.57 = 0.456
Chocolate cake 103.0 × 0.75 = 0.772
Ice cream 125.8 × 0.58 = 0.729
Coffee (dinner) 210.0 × 0.11 = 0.231
------
Total nitrogen in food 10.656 grams.
Total nitrogen in urine 7.730

Fuel value of the food 2231 calories.

NITROGEN BALANCE.—_Underhill._

Nitrogen Output.
Taken in. Nitrogen in Urine. Weight of Fæces (dry).

Feb. 9 7.832 grams. 7.49 grams. 9.5 grams.
10 7.674 6.14
11 9.770 8.02 32.0
12 9.483 8.82 9.5
13 7.622 7.17 28.0
14 10.656 7.73 24.0
------ ------ ------
103.0 grams contain 6.52% N.
53.037 45.37 + 6.715 grams nitrogen.
------ ----------------------
53.037 grams nitrogen. 52.085 grams nitrogen.

Nitrogen balance for six days = +0.952 gram.
Nitrogen balance per day = +0.158 gram.

Average Intake.

Calories per day 2068.
Nitrogen per day 8.83 grams.

On June 1, near the close of the experiment, a second nitrogen balance was attempted, with a view to seeing if under the existing conditions of life and activity it was possible to reduce the fuel value of the food, and at the same time diminish in still greater measure the quantity of proteid food taken. The results of this trial are seen in the accompanying tables, where for four days a careful comparison of output and intake is shown. It will be observed from these tables that the average fuel value of the food per day was reduced to 1785 calories, and that the average intake of nitrogen was restricted to 6.73 grams per day. The balance shown is a minus balance, although the deficiency per diem is not large. It is very obvious that both the nitrogen and fuel value of the food can be reduced considerably below the average maintained during the period of the first balance, but not to the degree attempted in the second balance, and secure nitrogen or body equilibrium. It will be noted in this last nitrogen balance, that the average daily output of nitrogen through the urine amounted to 6.46 grams, while the average nitrogen intake was 6.73 grams. The fuel value of the food, however, averaged only 1785 calories per day. It is quite evident, if the non-nitrogenous food had not been reduced quite so much, that a plus nitrogen balance would have been obtained. Still, it is obvious that under the conditions of life and activity, this subject needed to metabolize only about 40 grams of proteid per day, with the total fuel value of his food equal to about 2000 calories, in order to secure both body and nitrogen equilibrium. Here, again, we have an illustration of the possibility of physiological economy which shows itself in a reduction of the daily proteid food more than 50 per cent, with a reduction of the non-nitrogenous food fully 30 per cent, and with maintenance of health, strength and vigor equal, if not superior, to that which the subject has ever experienced.

_Wednesday, June 1, 1904._

Breakfast.—Champagne wafer 21.5 grams, tea 146 grams, sugar 15 grams.

Dinner.—Bread 67.4 grams, butter 15.1 grams, beefsteak 55.5 grams, potato 128 grams, asparagus 103.5 grams, tea 146 grams, sugar 15 grams, banana 83.5 grams.

Supper.—Bread 15.7 grams, butter 11.8 grams, banana and nuts 106 grams, crullers 90.2 grams, coffee 145 grams, sugar 15 grams.

Food. Grams. Per cent Nitrogen. Total Nitrogen.

Champagne wafer 21.5 × 0.64 = 0.138 gram.
Tea 146.0 × 0.015 = 0.022
Sugar 15 + 15 + 15 = 45.0 × 0.000 = 0.000
Bread 67.4 + 15.7 = 83.1 × 1.46 = 1.212
Butter 15.1 + 11.8 = 26.9 × 0.10 = 0.027
Banana 83.5 × 0.28 = 0.192
Beefsteak 55.5 × 4.72 = 2.620
Potato 128.0 × 0.32 = 0.410
Asparagus 103.5 × 0.35 = 0.362
Tea 146.0 × 0.033 = 0.048
Crullers 90.2 × 1.04 = 0.938
Banana and nuts 106.0 × 0.69 = 0.731
Coffee 145.0 × 0.060 = 0.087
------
Total nitrogen in food 6.787 grams.
Total nitrogen in urine 5.960

Fuel value of the food 1913 calories.

_Thursday, June 2, 1904._

Breakfast.—Bread 30 grams, tea 146 grams, sugar 15 grams.

Dinner.—Clam chowder 270.5 grams, bread 64 grams, butter 14.5 grams, lobster 36.5 grams, Saratoga chips 15 grams, caramel custard 79 grams, tea 146 grams, sugar 15 grams.

Supper.—Bread 35.2 grams, butter 13.8 grams, pineapple 148.7 grams, crullers 84.8 grams, tea 140 grams, sugar 15 grams.

Food. Grams. Per cent Nitrogen. Total Nitrogen.

Bread 30.0 × 1.46 = 0.438 gram.
Tea 146.0 × 0.045 = 0.066
Sugar 15 + 15 + 15 = 45.0 × 0.00 = 0.000
Bread 64 + 35.2 = 99.2 × 1.44 = 1.428
Butter 14.5 + 13.8 = 28.3 × 0.10 = 0.028
Clam chowder 270.5 × 0.34 = 0.920
Lobster 36.5 × 3.73 = 1.361
Saratoga chips 15.0 × 0.97 = 0.146
Caramel custard 79.0 × 0.77 = 0.608
Tea 146.0 × 0.036 = 0.053
Tea 140.0 × 0.036 = 0.050
Pineapple 148.7 × 0.054 = 0.080
Crullers 84.8 × 1.04 = 0.882
------
Total nitrogen in food 6.060 grams.
Total nitrogen in urine 5.810

Fuel value of the food 1921 calories.

_Friday, June 3, 1904._

Breakfast.—Bread 31 grams, tea 146 grams.

Dinner.—Fried ham 61 grams, asparagus 124.2 grams, baked potato 85 grams, bread 29 grams, butter 23.5 grams, tea 140 grams, sugar 15 grams, pineapple 74.8 grams.

Supper.—Bread 34 grams, butter 17.8 grams, pineapple 158.5 grams, tomato 132.5 grams, cup cake 121 grams, tea 140 grams, sugar 15 grams.

Food. Grams. Per cent Nitrogen. Total Nitrogen.

Bread 31 + 20 + 34 = 94.0 × 1.44 = 1.354 grams.
Tea 146.0 × 0.039 = 0.057
Fried ham 61.0 × 4.90 = 2.989
Asparagus 124.2 × 0.50 = 0.621
Baked potato 85.0 × 0.55 = 0.468
Butter 23.5 + 17.8 = 41.3 × 0.10 = 0.041
Tea 140.0 × 0.027 = 0.038
Sugar 15 + 15 = 30.0 × 0.000 = 0.000
Pineapple 74.8 + 158.5 = 233.3 × 0.065 = 0.152
Tea 140.0 × 0.054 = 0.076
Tomato 132.5 × 0.150 = 0.199
Cup cake 121.0 × 0.85 = 1.029
------
Total nitrogen in food 7.024 grams.
Total nitrogen in urine 7.300

Fuel value of the food 2011 calories.

_Saturday, June 4, 1904._

Breakfast.—Bread 32 grams, tea 140 grams.

Dinner.—Hash 133 grams, peas 151.5 grams, bread 61.4 grams, butter 16.1 grams, custard 150 grams, sugar 15 grams, tea 140 grams.

Supper.—Bread 62.5 grams, butter 17 grams, tea 140 grams, sugar 15 grams.

Food. Grams. Per cent Nitrogen. Total Nitrogen.

Bread 32.0 × 1.44 = 0.461 gram.
Tea 140.0 × 0.021 = 0.029
Hash 133.0 × 1.50 = 1.995
Peas 151.5 × 1.04 = 1.576
Bread 61.4 + 62.5 = 123.9 × 1.47 = 1.821
Butter 16.1 + 17 = 33.1 × 0.10 = 0.033
Custard 150.0 × 0.78 = 1.170
Sugar 15 + 15 = 30.0 × 0.00 = 0.000
Tea 140.0 × 0.033 = 0.046
Tea 140.0 × 0.030 = 0.042
------
Total nitrogen in food 7.173 grams.
Total nitrogen in urine 6.780

Fuel value of the food 1297 calories.

NITROGEN BALANCE.—_Underhill._

Nitrogen Output.
Taken in. Nitrogen in Urine. Weight of Fæces (dry).

June 1 6.787 grams. 5.96 grams. 10 grams.
2 6.060 5.81 10
3 7.024 7.30 25
4 7.173 6.78 6
------ ------ ------
51 grams contain 5.81 % N.
27.044 25.85 + 2.963 grams nitrogen.
------ ----------------------
27.044 grams nitrogen. 28.813 grams nitrogen.

Nitrogen balance for four days = -1.760 grams.
Nitrogen balance per day = -0.442 grams.

Average Intake.

Calories per day 1785.
Nitrogen per day 6.73 grams.

* * * * *

Dr. Arthur L. Dean, Instructor in Plant Physiology in the Sheffield Scientific School, twenty-five years of age, and weighing 64 kilos, likewise became a subject of study in this investigation. He is a man of strong physique, and as an undergraduate student at Harvard University trained for various athletic events. He began on the experiment October 13, 1903, and continued until April 3, 1904. From October 13th to October 27 he followed his usual dietary habits, simply reducing in some measure the amount of food consumed. During this period of fifteen days, the average excretion of nitrogen per day through the kidneys was about 12 grams. On the 28th of October he began to reduce in still greater measure the amount of proteid food eaten, and gradually diminished the extent of his proteid metabolism, although not to the same degree as the preceding subjects. He had full freedom of choice in the character and quantity of his diet, but his food was characterized by a predominance of vegetable matter, with an almost complete exclusion of meat.

For a period of nearly six months, or more exactly, from October 28 to April 3, the average daily output of nitrogen through the kidneys amounted to 8.99 grams, while the average daily output of uric acid was 0.386 gram. This daily excretion of 8.99 grams of nitrogen implies a metabolism of 56.18 grams of proteid. This, to be sure, means a reduction in proteid metabolism of about 50 per cent, as compared with the Voit and other standards, but does not show an economy equal to that practised by the preceding subjects. It is to be noted, however, in Dr. Dean’s case, that the body-weight did not show at any time in the experiment a tendency to diminish. In fact, all through the experiment his body-weight was a little higher than at the beginning.

DEAN.

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Physiological economy in nutrition, with special reference to the minimal proteid requirement of the healthy manChapter I: Experiments with Professional Men (3)

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