Summary of main results

1. Nitrogen Balance
See tables 4, 5, and 6 for individual data. Table 7 shows the individual and pooled regression equations of apparent nitrogen balance (i.e., without allowances for integumental and other insensible nitrogen losses) and nitrogen intake.

Figure 1 shows the individual variability and the upper 95 per cent confidence band for the pooled data of the fish-Supro mixture.

2. Relative Protein Quality of the Soybean Isolate
Based on the regression coefficients ("slope ratio"), nitrogen requirements for nitrogen balance ("maintenance intake"), and net protein utilization (NPU) shown in table 7, the quality of Supro 620 relative to cod fish was 82, 73, and 74 per cent, respectively (mean: 76 per cent). The fish-Supro mixture gave values of 115, 96, and 96 per cent, respectively, compared with fish alone.

3. Other Measurements
Anthropometric, blood, and urine indicators were not significantly affected by changes in dietary protein source.

TABLE 4. Summary of Nitrogen Balance Data for Young Men Given Different Levels of Fish Protein ¹

Protein level	Subject	Body wt. (kg)	Energy intake (kcal/kg)	Nitrogen balance (mg/kg)				Digestibility4 (%)
				Intake nitrogen	Urinary nitrogen	Faecal nitrogen	Nitrogen balance
0.35 g/kg/day	A	64.0	44 3	55.2	48.6	10.2	- 8.6
	B	57.8	46.2	56.2	67.0	11.4	- 27.2
	C	58.0	42.0	56.0	54.1	12.1	- 15.2
	D5	_	_	_	_	_	_
	E	64.1	44.9	55.9	51.5	12.5	- 13.1
	F	63.7	47.5	55.4	62.2	14.9	- 26.7
	G	57.3	45.5	56.7	56.2	11.9	- 16.4
	K6	70.8	47.1	56.2	58,9	8.1	- 15.8
	Mean	60.8	45.1	55.9	56.6	12.2	- 17.9	100.0
	S. D.	3 4	1.9	0.5	6.9	1.6	7.5
0,45 g/kg/day	A	63.7	45.5	71.3	61.2	10.5	- 5.4
	B	57.1	44.1	70.6	64.1	11.2	- 9.7
	C	57.8	42.1	72.3	64.9	13.7	- 11.3
	D	71.1	38.8	69.9	60.2	9.7	- 5.0
	E	65.1	44.2	70.8	61.9	12.1	- 8.2
	F	63.0	47.0	72.1	74.0	13.3	- 20.2
	G	57.9	45.1	72.2	64.8	11.2	- 8.8
	K6	71.3	47.8	71.8	86.6	8.8	- 28.6
	Mean	62.2	43.8	71.3	64.4	11,7	- 9.8	100.0
	S.D.	5.1	2.7	0.9	4.6	1.5	5.1
0,55 g/kg/day	A	63.5	44.6	87.4	64.6	11.6	+ 6.2
	B	57.5	46.6	87.3	72.2	11.1	- 1.0
	C5	-	-	-	-	-	-
	D	70.3	39.3	86.3	73.5	8,7	- 0.9
	E	64.7	44.5	87.0	74.5	16.8	- 9.3
	F	63.2	46.9	87.7	78.2	15.2	- 10.7
	G	58.7	44.5	86.9	70.9	13.3	- 2.3
	K6	70.7	48.2	88.4	109,1	9.1	- 34.8
	Mean	63.0	44.4	87.1	72.3	12.9	- 3.0	99.4
	S.D.	4.6	2.7	0.5	4.5	2.9	6.2
0.65 g/kg/day	A	64.5	43.7	103.1	80.6	12,9	+ 4.6
	B	57.9	45.3	102.4	92.7	1 2.4	- 7.7
	C	58.6	41.6	102.9	84.8	13.0	+ 0.1
	D	70.1	39.4	102.4	77.3	10.1	+10.0
	E	64.2	44.9	103.7	90.2	12.8	- 4.3
	F	63.6	44.6	103.0	89.5	14.9	- 6.4
	G	58.4	44.9	101.5	82.7	14.4	- 0.6
	K6	70.9	46.1	104.2	118.7	8.9	- 28.4
	Mean	62.3	43.5	102.7	84.5	1 2.9	- 0.6	99.5
	S.D.	4.4	2.2	0.7	5.6	1.5	6.3

1 Values are means for the last five days at each protein level.
2 Mean faecal nitrogen loss for the last eight days at each protein level,
3 True nitrogen balance was calculated using 5.0 mg N/kg as an estimate of miscellaneous losses.
4 True digestibility was calculated using 1 2.4 mg N/kg as faecal metabolic nitrogen,
5 The experiments of subject D in low-protein diet 1 and Subject C in low-protein diet 3 were interrupted because of febrile upper respiratory infections.
6 All data of subject K were omitted from further analyses because the nitrogen balance was inversely related to nitrogen intake.

TABLE 5. Summary of Nitrogen Balance Data for Young Men Given Different Levels of Supro 620¹

Protein level	Subject	wt.² (kg)	Nitrogen balance (mg/kg)				Digestibility4 (%)
			Intake nitrogen	Urinary nitrogen	Faecal nitrogen	Nitrogen balance
0.35 g/kg/day	M	68.2	56.0	67.7	7.0	- 23.8
	N	53.9	56.2	60.3	10.2	- 19.3
	O	54.6	55.9	68.1	11.4	- 28.6
	P	74.0	56.0	62.2	13.4	- 24.6
	Q	77 5	55.9	59.7	11.2	- 20.1
	Mean	65.6	56.0	63.6	10.6	-23.3	100.0
	S.D.	10.9	0.1	4.0	2.3	3.8
0.45 g/kg/day	M	68.2	72.0	76.5	6.5	- 16.0
	N	53,9	72.0	73.5	8.7	- 15.2
	O	54.6	72.0	81.1	14.7	- 28.8
	P	74.0	72.2	69.7	10.4	- 13.0
	Q	77.0	72.0	74.2	12.5	- 19.7
	Mean	65.6	72.0	75.0	10.6	- 18.5	100.0
	S.D.	10.9	0.1	4.2	3.2	6.2
0.55 g/kg/day	M	68.2	88.0	82.7	8.5	- 8.5
	N	53.9	88.1	84.2	11.9	- 13.0
	O	54.6	88.1	89.7	16.3	- 23.0
	P	74.0	88.0	85.4	11.9	- 14.3
	Q	77.5	88.1	88.0	12.1	- 17.0
	Mean	65.6	88.1	86.0	12.1	- 15.1	100.0
	S.D.	10.9	0.1	2.8	2.8	5.4
0.65 g/kg/day	M	68.2	104.0	95.6	8.7	- 5.3
	N	53 9	103.9	97.2	10.6	- 8.9
	O	54.6	104.0	98.4	14.1	- 13.4
	P	74.0	104.1	90.5	14.3 -	5.8
	Q	77,5	104.1	93.3	15.1 -	9,3
	Mean	65.6	104.0	95.0	12.6 -	8.5	99.8
	S.D.	10.9	0.1	3.2	2.8	3.3

1 Energy intake: 45 ± 1 kcal/kg
2 Values ate means for the last five days at each protein level.
3 Mean faecal nitrogen loss for the last eight days at each protein level.
See footnotes for table 4.

TABLE 6. Summary of Nitrogen Balance Data for Young Men Given Different Levels of a Mixture Containing 50 per cent Fish Protein and 50 per cent Supro 620¹

Protein level²	Subject	Body wt. (kg)	Energy intake (kcal/kg)	Nitrogen balance (mg/kg)				Digestibility4 (%)
				Intake nitrogen	Urinary nitrogen	Faecal nitrogen	Nitrogen balance
0.35 g/kg/day	A	62.9	44.1	56.1	57.2	14.1	- 20.2
	B	60.4	47.9	54.6	55.0	13.2	- 18.6
	C	69.5	44.6	55.5	69.2	12.9	- 31.6
	D	69.0	39A	55.2	46.8	9.3	- 5.9
	E	62.9	44.4	55.2	55.3	1 7.0	- 22.1
	H	60.2	44.9	55.8	56.0	13.6	- 18.8
	I	52.2	45.8	55.7	54.8	12.1	- 16.2
	J	60.4	46.7	56.6	56.0	10.8	- 15.2
	Mean	60.9	44.7	55.6	56.3	12.9	- 18.6	99.1
	S.D.	4.7	2.5	0.6	6.1	2.3	7.2
0.45 g/kg/day	A	62.8	44.1	72.3	70.0	12.9	- 17.6
	B	58.7	48.2	72.4	73.3	13.8	- 19.7
	C	59.8	44.4	71.1	63.5	14.0	- 11,4
	D	68.6	39.7	71.4	61.7	9.6	- 4.9
	E	63.4	44.7	71.6	71.3	15.9	- 20.6
	H	60.6	44.6	71.3	65.0	14.4	- 13.1
	I	52.5	45.6	71.2	62.3	11.6	- 7.7
	J	60.9	46.1	70.9	71.3	11.3	- 16.7
	Mean	60.9	44.7	71.5	67.6	12.9	- 14,0	99.3
	S.D.	4.6	2.4	0.5	4.0	2.0	5.7
0,55 g/kg/day	A	63.1	44,9	87.8	80.2	13.9	- 11,3
	B	59.2	49.8	87.7	89.2	14.9	- 21.4
	C	59.7	40.5	86.9	67.5	14.6	- 0.2
	D	69.0	38.4	86.7	69.3	8.7	+ 3.7
	E	63.1	44.2	86.5	70.5	17.0	- 6.0
	H	60.8	44.4	86.8	70.4	16.3	- 4.9
	I	52.6	45.5	87.1	81.7	11.8	- 11.4
	J	61.2	45.1	86.3	85.6	12.4	- 16.7
	Mean	61.1	44.1	87.0	76.8	13.7	- 8.5	98.5
	S.D.	4.6	3.4	0.5	8.4	2.7	8.3
0.65 g/kg/day	A	63.8	44.4	10.7	77.7	1 2.2	+ 7.8-
	B	60.1	48.1	102.2	87.5	14.0	- 4.3
	C	59.7	44.5	102.8	91,1	14.2	- 7.5
	D	69.0	39.4	102.5	75.9	9.4	+ 12.2
	E	62.8	45,4	102.7	76.6	1 5.4 +	5,7
	H	62.8	45.4	103.5	81.9	16.7 -	0.1
	I	52.7	45.4	102.6	76.5	13.3 +	7.8
	J	60.8	45.4	102.6	92.3	12.0 -	6.7
	Mean	61.2	44.7	102.7	82.4	13.4 +	1.9	99.0
	S.D.	4.6	2.4	0.4	6.9	2.2	7.5

1 Values are means for the lest five days at each protein level,
2 Each period consists of one day on protein-free diet and ten days on experimental diet,
3 Mean faacal nitrogen loss for the last eight days at each protein level,
4 True digestibility was calculated using 12,4 mg N/kg as faecal metabolic nitrogen.

TABLE 7. Summary of Maintenance Nitrogen and Equations Relating Nitrogen Balance to Nitrogen Intake

Individual data for apparent balance
Fish				Supro				Mixture
Subject	Regression equation¹	Main- tenance²	NPU	Subject	Regression equation	Main- tenance	NPU	Subject	Regression equation	Main- tenance	NPU
A	Y= 0.320X-21.2	66.3	69.4	M	Y= 0.396X-40.0	101.0	45.5	A	Y = 0.577X-51.3	88.9	51.7
B	Y=0.430X-40.4	94.0	49.0	N	Y=0.210X-25.9	123.3	373	B	Y=0.249X-30.8	123.7	37.2
C	Y = 0.322X-29.4	88.6	50.9	O	Y= 0.320X-44.1	137.8	33.4	C	Y = 0.528X-49.4	93.6	49.2
D	Y =0.416X-33.4	72.5	63.5	P	Y= 0.345X-37.0	107.2	42.9	D	Y= 0.399X-25.2	63.2	72.8
E	Y = 0.158X-16.3	103.2	44.6	Q	Y= 0.218X-29.0	133.0	34.6	E	Y = 0.620X-54.7	88.2	52.1
F	Y = 0.445X-46.4	104.3	44.1					H	Y = 0.405X-36.3	89.6	51.3
G	Y = 0.363X-30.8	84.8	54.2					I	Y = 0.435X-36.3	83.4	55.1
K¦	Y=0.274X +0.03	-	-					J	Y=0.171X-22.3	130.4	35.3
Mean	0.357X	87.7	53.7	Mean	0.298X	120.5	38.7	Mean	0.423X	95.1	50.6
S.D.	0.105	14.5	9.6	S.D.	0.081	16.0	5.3	S.D.	0.155	21.8	11.5
C.V.	29.4	12.7	5.2	C.V.	27.3	19.3	2.0	C.V.	36.6	20.7	5.8

¹Y: Nitrogen balance (mg/kg), X: Nitrogen intake (mg/kg).
² Maintenance: Nitrogen intake for the maintenance of nitrogen equilibrium (mg/kg).
³ K: emitted from group analyses (see table 4).

Pooled data

Y=0.365X-31.8	Y=0.298X-35.2	Y=0.423X-38.3
Maintenance: 87.1±17.2	Maintenance: 118.1±15.4	Maintenance: 90.5±17.1
N = 26, r = +0.727	n = 20, r = +0.774	n = 32, r = +0.727
NPU = 52.8	NPU = 38.9	NPU = 50.8

Statistical analysis
Fish vs. Supro: t = 6.337, P < 0.01, significant
Fish vs. Mixture: t = 0.751, P > 0.10, not significant
Mixture vs. Supro:t = 5.877, P < 0.01, significant

FIG. 1. Relationship between Nitrogen Intake and Nitrogen Balance for the Mixed Protein of Fish and Supro 620

TABLE 8. Amino Acid Pattern Codfish and Soybean (Amino Acid Content of Foods, FAO, 1970)

	Nitrogen (g/100 9)	Isoleu- cine	Leucine	Lysine	Methionine	Methionine - Cystine	Phenyl-alanine	PhenyI-alanine + Tyrosine	Threonine	Tryptophan	Valine	Total EAA
FAOIWHO reference (1973)		250	440	340	-	(220)*	-	(380)	250	60	310	2,250
Codfish	2.72	293	533	626	211	(284)	316	(561)	323	70	327	3,017
Soybean	6.65	284	486	399	79	(162)	309	(505)	241	80	300	2,457
50% soy + 50%cod	4.68	289	510	513	145	(223)	313	(533)	282	75	314	2,737

*Numbers in parentheses are totals.