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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
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View the documentObjective
View the documentExperimental details
View the documentSummary of main results
View the documentConclusions

Experimental details

1. Subjects
Twenty-one male university students served as the subjects in these three series of experiments. They lived in a metabolic ward of our laboratory throughout the experiment. During the study, they continued their daily routine activities but were not allowed to do any hard physical work. Characteristics of the students are shown in table 1.

2. Diets
Each subject was given, successively, four levels of low-protein diets. Protein sources were cod fish (as a standard) for eight subjects, a soybean protein isolate (Supro) for five subjects, and a 50:50 mixture of both for eight subjects. Among these, five men received both the cod and mixed protein diets (see table 1). The fish and Supro were prepared as paste products (kamaboko) and fed in equal amounts three times a day. An example of the diet composition is shown in tables 2 and 3.

Each experimental period consisted of one day on a protein-free diet and ten days

TABLE 1. Characteristics of the Subjects

  Subject Age (years) Ht. (cm) Wt (kg) Chest circumference (cm) Subscapular skin-fold (mm) BMR
(kcal/kg)
Blood pressure (mmHg)
Fish A 21 171 63.3 86.1 13.5 22.7 125/75
B 20 164 56.5 84.6 7.5 25.6 135/82
C 19 171 58.1 84.8 8.2 27.4 145/90
D 24 171 69.8 97.6 15.2 21.2 120/75
E 22 179 64.3 90.0 9.5 22.4 115/75
F 22 172 63.2 90.8 11.8 22.5 130/85
G 20 168 57.6 83.4 11.0 24.5 120/70
K 22 166 71.6 91.8 18.8 25.6 125/84
Mean 21 170 63.1 88.6 11.9 24.0 127 80
S.D. 2 5 5.6 4.8 3.8 2.1 10 7
Supro M 21 173 68.2 92.0 7.0    
N 21 161 53.9 87.4 8.0    
O 28 164 54.6 89.8 7.0    
P 22 164 74.0 92.7 12.0    
Q 26 174 77.5 99.8 14.0    
Mean 24 167 65.6 92.3 9.6    
S.D. 3 6 10.9 4.7 3.2    
Mixed A 21 171 63.4 84.9 15.3 21.7 105/70
B 21 164 59.2 86.7 7.5 21.9 133/92
C 20 170 59.4 85.1 7.8 24.2 148/93
D 24 171 68.3 98.3 15.0 24.8 118/75
E 22 178 62.3 88.5 8.5 25.9 122/83
H 25 170 60.3 87.8 8.5 23.2 95/58
I 21 166 52.0 83.4 6.0 27.3 108/72
J 21 168 61.0 85.7 10.5 25.9 117/83
Mean 22 170 60.7 87.6 9.9 24.4 118 77
S.D. 2 4 4.6 4.6 3.5 2.0 17 12

 

TABLE 2. Diet Composition (Example). Subject: 65 kg; mixed protein 0.55 g/kg; energy 45 kcal/kg.

Materials g/day
Cod kamaboko * 155
Supro kamaboko* 107.5
Sugar 323
Cornstarch 300
Margarine 32
Corn oil 30
Agar 3
Baking powder 5
Salt 2.5
Mineral mixture 6
Vitamin mixture 3

* For composition of the kamaboko, see table 3. The nitrogen contents are as follows: Dried cod 89.6 mg/g; dried Supro 147.2 mg/g; cod kamabako 18.45 mg/g; Supro kamaboko 26.6 mg/g. Nitrogen intake was 2.86 g/day equally in cod and Supro.

TABLE 3. Composition of Kamaboko Products

 

Cod

Supro

  Parts % Parts %
Cod paste 100 77.2 - -
Supro 620 - - 20 17.5
NaCI 3 2.3 3 2.6
Potato starch 5 3 9 5 4 4
Sugar 1.5 1.2 1.5 1.3
Water 20 15.4 85 74.2

Total 129.5 100.0 114.5 100.0 on the experimental diet, followed by three days on a free choice (ad libitum) diet. Four periods were included in the study, with 0.35, 0.45, 0.55, and 0.65 9 protein/ kg/day fed to each man in a random order. Energy intake was constant for each individual to maintain body weight (mean + S.D. = 44.6 + 2.4 kcal/kg; range = 38.4 to 49.8).

3. Measurements and Indicators

a. Anthropometry: body weight, height, arm and leg circumferences, skin-fold thickness.
b. Blood analyses: RBC and WBC count, haemoglobin, haematocrit.
c. Plasma analyses: total proteins (Biuret), albumin (dye-binding, HABCA), urea (indophenol colour reaction), glucose (Somogyi-Nelson), triglyceride (Van Handel), total cholesterol (Zak-Hanly), Na and K (atomic absorption), SGOT and SGPT (Reitman-Frankel). d. Urine analyses: urea (urease-indophenol), ammonia (phenol-hypochlorite), creatinine (Folin-Wu), uric acid (phosphotungstic acid), Na and K (atomic absorption).
e. Nitrogen balance: total nitrogen in diets, faeces, and urine was measured with a semi-micro-Kjeldahl technique during the last five days of each ten-day period on the experimental diets.