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close this bookProtein-Energy Requirements of Developing Countries: Evaluation of New Data (UNU, 1981, 268 p.)
close this folderResearch papers: Protein requirements-adults, standard protocols
close this folderThe evaluation of soy protein isolate alone and in combination with fish in adult Japanese men
View the document(introduction...)
View the documentObjective
View the documentExperimental details
View the documentSummary of main results
View the documentConclusions

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
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.