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

by R. H. Chittenden

		Nitrogen Taken in.		Output.
				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.

Date.		Body-weight.	Urine.
			Volume. 24 hours.	Sp. Gr.	Nitrogen.		Uric Acid.		P₂O₅.
1903		kilos	c.c.		grams		gram		grams
Oct.	13	63.2	1100	1017		10.63		0.323		2.38
	14		1050	1020		9.83
	15		1390	1018		14.93		0.432		1.98
	16		1370	1017		11.26
	17		1350	1019		11.18
	18		1670	1017		11.62		0.490		2.51
	19	63.2	1075	1018		10.19
	20		1260	1015		9.98		0.483		1.88
	21		1350	1020		13.04
	22		1405	1015		11.38		0.431		2.07
	23		1240	1020		11.98
	24		1200	1023		11.16
	25		1365	1018		11.97		0.395		2.02
	26		1195	1020		10.75
	27		1240	1021		11.90		0.477		1.97
	28		1704		⎫	9.29 daily average		0.398 daily average		1.69 daily average
	29		1105		⎪
	30	64.5	1180		⎬
	31		910		⎪
Nov.	1		710		⎭
	2		1540		⎫	8.54		0.354		1.65
	3		1250		⎪
	4		1300		⎬
	5		975		⎪
	6		1150		⎭
	8	64.6	1192	1025		10.86		0.493
	9		845		⎫	8.84		0.368		1.85
	10		1255		⎪
	11		1245		⎪
	12		1540		⎬
	13		940		⎪
	14		1300		⎪
	15		1065		⎭
	16	64.5	1165		⎫	9.45
	17		910		⎭
	18		840			10.59		0.444
	19		1720	1012		10.32		0.331		1.95
	20		640	1022		8.60		0.336	⎫	1.75
	21		1310	1016		9.27		0.378	⎬
	22		720	1026		8.42		0.415	⎭
	23	64.7	900		⎫	8.22		0.322		1.74
	24		1520		⎪
	25		1095		⎪
	26		710		⎬
	27		700		⎪
	28		1140		⎪
	29		1200		⎭
	30		820		⎫	8.15		0.362		1.68
Dec.	1		1335		⎪
	2	64.5	940		⎪
	3		970		⎬
	4		1240		⎪
	5		1190		⎪
	6		720		⎭
	7		1160		⎫	9.12		0.342		2.11
	8		960		⎪
	9		850		⎪
	10		935		⎬
	11		945		⎪
	12		1425		⎪
	13	64.3	1065		⎭
	14		770		⎫	9.08
	15		790		⎭
	30		1230	1017	⎫	8.60		0.375		1.80
	31	66.1	1525	1020	⎪
1904					⎬
Jan.	1		1010	1021	⎪
	2		1270	1020	⎪
	3		1230	1020	⎭
	4		820		⎫	8.42		0.338		1.76
	5		1425	1018	⎪
	6		1100	1021	⎪
	7		1025	1021	⎬
	8		760		⎪
	9		1450	1019	⎪
	10	65.8	1410	1016	⎭
	11		1030	1017	⎫	8.51		0.428
	12	65.0	830	1023	⎪
	13		790	1025	⎪
	14		1070	1020	⎬
	15		1300	1019	⎪
	16		925	1025	⎪
	17		1100	1023	⎭
	18		850	1025	⎫	8.23
	19		1120	1019	⎪
	20		1005	1020	⎪
	21		1270	1020	⎬
	22		980	1020	⎪
	23		650		⎪
	24		980	1024	⎭
	25	65.5	1000		⎫	8.85		0.395		1.67
	26		940		⎪
	27		1350		⎪
	28		840		⎬
	29		675		⎪
	30		740		⎪
	31		1160	1017	⎭
Feb.	1		700		⎫	8.22		0.381		1.19
	2		860		⎪
	3		925		⎪
	4		590		⎬
	5		835		⎪
	6		935		⎪
	7		930		⎭
	8		1035	1017		9.00
	9	64.1	800	1027		8.64		0.432
	10		940	1020		8.29		0.314
	11		720	1030		8.55		0.364
	12		860	1023		9.93		0.348
	13		980	1022		8.87		0.379
	14	63.9	1285	1022		8.33		0.385
	15		910		⎫	9.30		0.301
	16		1210		⎪
	17		1455		⎪
	18		1000	1022	⎬
	19		1420		⎪
	20		1050		⎪
	21	64.5	1365		⎭
	22		765		⎫	9.685		0.423
	23		1070		⎪
	24		1080		⎬
	25		1495		⎪
	26		970		⎪
	28		750		⎭
	29		725		⎫	10.31		0.410
Mar.	1		1100		⎪
	2		990	1024	⎪
	3		1180		⎬
	4		1100		⎪
	5		1010		⎪
	6		970		⎭
	7		790		⎫	8.99		0.433
	8	64.4	670		⎪
	9		840		⎪
	10		1110		⎬
	11		1090		⎪
	12		755		⎪
	13		1220		⎭
	14		745		⎫	8.24		0.368
	15		1030		⎪
	16		1040		⎪
	17		1080		⎬
	18		1390		⎪
	19		795		⎪
	20	64.0	840		⎭
	21		720		⎫	9.26		0.545
	22		970		⎪
	23		1200		⎪
	24		845		⎬
	25		1000		⎪
	26		1180		⎪
	27		1750		⎭
	28		820		⎫	9.59		0.409
	29		710		⎪
	30		1100		⎪
	31		770		⎬
Apr.	1		1250		⎪
	2		885		⎪
	3	65.0	630		⎭
Daily average from Oct. 28, 1903			1035	1021		8.99		0.386		1.73