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

by R. H. Chittenden

Commencing with May 14, 1903, the amount of nitrogen excreted from the kidneys was determined from time to time, but not each day, since it was very soon found that Mr. Beers showed great regularity in his dietary habits, and a corresponding regularity in the composition of the output. This regularity was due in large measure to the fact that the subject became, for the time at least, practically a vegetarian. The beneficial effects noted in his own experience with abstention from meat led to his voluntarily excluding it from his daily diet, so that from January, 1903, to June, 1904, the subject practically tasted meat, fish, or eggs on only four occasions, namely, the 26th day of November, 1903, May 19, 20, and 21, 1904. With this limitation to a vegetable diet and with regular methods of living, the nitrogenous waste material was found to be constant within very narrow limits. Emphasis, however, should be laid upon the fact that there was no prescription of diet, but perfect freedom of choice, although this choice was limited wholly to vegetable and cereal foods.

The accompanying tables give the output of nitrogen, uric acid, etc., through the kidneys for various dates between May 14, 1903, and June 15, 1904. Scrutiny of these tables shows that the average daily output of nitrogen, so far as the data show, amounted to 8.58 grams. This indicates an average daily metabolism of 53.62 grams of proteid material.

Likewise noticeable is the perfectly steady body-weight throughout this whole period of time, while the low level of 8.5 grams of metabolized nitrogen testifies to an economy in the use of proteid food, which indicates that in this subject at least the needs of the body for proteid food could easily be met by an amount equal to about one-half that called for by the Voit and similar standard dietaries.

BEERS.

Date.		Body-weight.	Urine.
			Volume. 24 hours.	Sp. Gr.	Nitrogen.		Uric Acid.		P₂O₅.
1904		kilos	c.c.		grams		gram		grams
May	14	61.1	940	1020		8.23		0.330		1.82
Oct.	8		920	1014		6.40		0.374		1.47
	13	61.1	740	1026		8.74		0.375		1.61
	14		780	1024		8.37
	15		970	1018		8.90		0.374		1.04
	16		1365	1014		9.09
	17		1295	1013		8.86
	18		1400	1013		7.56		0.347		1.57
	20	61.1	1304	1014		8.14		0.328		1.44
	21		1510	1012		7.97
	22		1450	1012		8.26		0.338		1.95
	23		1130	1013		7.86
	24		1060	1019		8.46
	25		1275	1015		8.25		0.375		1.74
	26		1390	1014		7.34
	27	61.4	1000	1020		7.50		0.344		1.38
Nov.	21	61.4	670	1025		8.72
	22		925	1017		8.21		0.335		1.28
	23		585	1027		8.36
	24		885	1023		8.02		0.354
	25		800	1026		7.92
	26		1095	1020		10.77[*]		0.364		1.53
Jan.	5	61.4	1110	1018		8.99		0.324
	7		650	1024		8.15		0.278		1.29
	8		710	1020		7.88
	9		910	1023		8.73
	10		890	1020		8.01		0.327		1.21
	11		875	1017		7.51
	12		480	1029		6.77
	13		580	1023		8.00		0.398
	14		765	1022		8.35
	15		1360	1017		9.22
	16	61.4	990	1020		8.79
	17		835	1024		8.47		0.354
	18		780	1020		8.05
	19		790	1022		8.10		0.382
Feb.	9		860	1023		8.46		0.355
	10	61.4	850	1024		8.57		0.226
	11	61.4	750	1022		8.55		0.352
	12	61.4	595	1026		8.46		0.368
	13	61.4	640	1027		8.75		0.425
	14	60.8	730	1025		8.28		0.353
Apr.	18	61.5	610	1025		7.69	⎫	0.365 daily average
	19	61.5	870	1020		9.87	⎪
	20	61.5	985	1019		8.87	⎪
	21	61.5	795	1024		8.25	⎬
	22	61.5	1090	1019		9.02	⎪
	23	61.5	970	1022		8.44	⎪
	24	61.5	810	1021		7.30	⎭
	25	61.5	850	1018		6.94	⎫	0.691
	26	61.5	620	1024		7.11	⎪
	28		450	1027		8.58	⎬
	29		650	1025		9.52	⎪
	30		1260	1018		10.20	⎪
May	1		1060	1017		8.71	⎭
	2		610	1025		8.16
	3		650	1022		8.70
	4	61.5	870	1019		8.51
	5	61.3	610	1025		8.31
	6	61.3	655	1026		8.72	⎫	0.356
	7		680	1025		8.53	⎪
	8	60.8	490	1026		7.00	⎪
	9	61.3	550	1026		7.59	⎬
	10		705	1025		7.78	⎪
	11		730	1025		8.28	⎪
	12		800	1025		9.36	⎭
	16		715	1022		7.29
	17		990	1018		6.95
	18		715	1026		7.81
	19		845	1926		10.45[†]
	20	61.5	1170	1020		11.02[†]
	21	61.2	795	1025		10.02[†]
	22		835	1020		8.42
	23		695	1025		9.42
	24		660	1025		9.82
	25		700	1025		9.91	⎫	0.434
	26		620	1026		8.59	⎪
	27		665	1026		9.53	⎬
	28	61.2	960	1021		10.31	⎪
	29		790	1023		9.24	⎭
	31		930	1025		10.44
June	1		855	1018		8.76
	2		850	1023		8.01
	3		860	1020		9.24
	4	61.4	1145	1021		10.17
	5		590	1024		7.47
	6		510	1029		7.53
	7		620	1027		8.26
	8		985	1020		8.45
	9		1220	1020		8.49
	10		1220	1017		8.28
	11		1710	1013		8.82
	12		925	1017		7.11
	13		920	1020		8.01
	14		1090	1015		8.64
	15	61.5	915	1022		8.68
Daily average			880	1021		8.58		0.365		1.49

[*] Turkey eaten on this day.

[†] On these three days, meat, fish, and eggs were eaten.

On February 9, a nitrogen balance was attempted covering a period of six days, in which there was an exact comparison of the nitrogen income and output. In this balance period it will be observed that the total amount of nitrogen taken in for the six days was 53.108 grams, while the output of nitrogen through the kidneys amounted to 51.07 grams. The nitrogen excreted through the fæces, however, brought the total nitrogen output up to 58.83 grams, thus making a minus balance for the six days of 5.722 grams of nitrogen. During this period the average fuel value of the food per day was 2168 calories. The average daily output of metabolized nitrogen during the period was 8.5 grams, practically identical with the average daily excretion of nitrogen through the kidneys for the entire year, so far as determined. We have here a distinct minus balance, due either to an insufficient amount of proteid food, or an insufficient fuel value.

Tuesday, February 9, 1904.