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Jin Soon Ju
Department of Nutrition and Biochemistry Korea University, Medical College, Seoul, Republic of Korea
Objective
To evaluate the long-term metabolic response of free-living Korean subjects consuming local protein sources fed at, or slightly below, habitual intake.
Experimental Design
Environment
Subjects were free-living, but consumed diets in the metabolic unit. Temperature ranged between - 2° to 28° C Specific values during each dietary period are given in table 1.
Subjects
Six male medical students aged 23 to 25 years served as subjects. Their characteristics are described in table 2. They were "healthy" as determined by medical exam and routine clinical laboratory tests. They belonged to the Korean middle class.
Diets
The diet consisted of natural foods and was based on customary intake as identified by surveys. The composition of the diet is given in table 3. Animal protein ranged between 25 to 30 per cent of total. Three meals per day were given. A vitamin supplement was given daily to meet recommendations.
TABLE 1. Environment and Duration of the Study
| Period | Duration | Season | Outdoor Temperature | Feeding |
| I | 26 August to 17 October 1980 (51 days) | Late summer to middle autumn | 20-26° C (22°) | Local diet at metabolic unit |
| II | 19 October to 6 December 1980 (48 days) | Middle autumn to early winter | - 2-20° C (14°) | Local diet at metabolic unit |
| III | 4 March to 25 April 1981 (53 days) | Early spring to middle spring | 5 12° C (8°) | Local diet at metabolic unit |
Three 50-day periods following the design shown in table 6 were used to test the protein-energy adequacy of the diets. Energy content was calculated from proximate composition using the Atwater factors. Protein content was calculated from N analysis of ingredients.
Measurements Taken
Urinary nitrogen excretion was measured daily. Faecal samples were pooled for the first five days of each week. N balance was computed using 5 mg N/kg for skin and miscellaneous losses. Weight was measured daily.
Results
The main results are summarized in table 4, which shows the response for each subject per period. Table 5 shows the mean response for all periods.
TABLE 3 Composition of Experimental Diets (g/day)a
| Food | Amount (9) |
| 1 Rice | 286-319 |
| 2 Barley | 20-23 |
| 3 Noodles | 2-21 |
| 4 Bread | 69-109 |
| 5 Rice cake | 71-88 |
| 6 Potato | 45-83 |
| 7 Soy-bean curd | 34-45 |
| 8 Soy-bean paste | 10-16 |
| 9 Soy sauce | 22-25 |
| 10 Radish pickle | 6-7 |
| 11 Radish, fresh | 76 99 |
| 12 Carrot | 0-13 |
| 13 Spinach | 38-2 |
| 14 Cabbage | 0-16 |
| 15 Cucumber | 0-23 |
| 16 Green pepper | 0-9 |
| 17 Green onion | 23-32 |
| 18 Pumpkin | 0-23 |
| 19 Garlic | 7-18 |
| 20 Kim-chi (seasoned vegetable) | 146-156 |
| 21 Apple | 86-100 |
| 22 Pear | 43-57 |
| 23 Seaweed | 2-3 |
| 24 Jam | 29-37 |
| 25 Tomato ketchup | 0-19 |
| 26 Drink, carbonated | 0-24 |
| 27 Egg | 23-43 |
| 28 Milk | 107-154 |
| 29 Beef | 33 48 |
| 30 Sausage | 18-23 |
| 31 Fish, pollack | 0-7 |
| 32 Card-fish | 6-7 |
| 33 Fish jelly | 0-17 |
a. "Multivitamin" Tablets (Vita-fresh Vitamin Co, Inc., Garden Grove, Calif., USA) was given once a day in addition to the diet
TABLE 4 Summary of Metabolic Response (Mean + SD)
| Subject | Exp. (kg) | Body Weight (kg) | Kcal Intake (mg/kg) | N Intake (mg/kg) | Unne N-out (mg/kg) | Faecal N-out (mg/kg) | N Balance | Protein Absorption Rate (%) Range Mean | Other Observations |
| 1 | I | 60.34 | 42 + 3 | 196 ± 16 | 129 ± 34 | 25 ± 11 | 36 ± 40 | 79-92(87) | |
| II | 60.59 | 39 ± 2 | 170 ± 11 | 140 + 29 | 23 ± 3 | 5 + 30 | 84 89(86) | ||
| III | 62.14 | 39 ± 1 | 183 ± 7 | 135 ± 20 | 23 ± 4 | 19 ± 21 | 84-89(87) | ||
| 2 | I | 54.35 | 48 ± 2 | 230 ± 18 | 165 ± 18 | 43 ± 7 | 17 ± 24 | 79-83(81) | Examination stress |
| II | 55.00 | 45 ± 2 | 201 ± 18 | 176 ± 25 | 39 ± 7 | - 23 ± 15 | 74-85(81) | fourth week | |
| III | 54.87 | 44 ± 2 | 218 ± 11 | 174 ± 24 | 34 ± 6 | 6 ± 24 | 80 88(84) | ||
| 3 | I | 71.25 | 37 ± 1 | 172 ± 9 | 141 ± 27 | 23 ± 7 | - 2 ± 35 | 80-89(87) | Mother hospitalized |
| II | 71.45 | 34 ± 1 | 150 + 6 | 134 ± 17 | 24 ± 5 | - 15 ± 14 | 82-87(84) | Mother died third week | |
| III | 70.96 | 37 ± 2 | 184 ± 11 | 156 ± 21 | 32 ± 4 | - 5 ± 17 | 81-84(83) | Fourth week Gl trouble digest. | |
| 4 | I | 57.94 | 42 ± 3 | 173 ± 12 | 128 ± 24 | 34 ± 8 | 6 ± 22 | 74-85(80) | Examination stress |
| II | 57.96 | 41 ± 4 | 204 ± 2 | 169 ± 20 | 48 ± 6 | - 22 ± 28 | 73-82(76) | fourth week | |
| III | 58.21 | 43 ± 3 | 189 ± 12 | 147 ± 19 | 39 ± 9 | - 5 ± 19 | 72-85(78) | Cold fifth week | |
| 5 | I | 57.70 | 45 ± 2 | 183 ± 6 | 145 ± 27 | 38 ± 12 | - 11 ± 30 | 72-39(79) | Examination stress |
| II | 58.42 | 42 ± 2 | 213 ± 11 | 174 ± 21 | 41 ± 11 | - 8 ± 21 | 73-86(81) | fourth week | |
| III | 59.41 | 42 ± 2 | 222 ± 11 | 164 ± 24 | 32 ± 6 | 18 ± 233 | 82-88(86) | ||
| 6 | I | 66.73 | 38 + 2 | 156 ± 6 | 128 ± 28 | 33 ± 5 | - 6 ± 20 | 74-82(79) | Examination stress |
| II | 65.84 | 38 + 1 | 190 ± 8 | 163 ± 17 | 34 + 4 | - 13 ± 4 | 78-85(82) | Dental inflammation | |
| III | 64.57 | 38 + 3 | 200 ± 17 | 160 ± 20 | 38 ± 10 | - 1 + 30 | 69-86(81) | Dental abscess third and fourth weeks |
TABLE 5. Individual Mean Metabolic Response for the Three Periods
Subject N |
Body Weight (kg) |
Energy Intake (ma Nlkg) |
Protein Intake (ma N/kg) |
Urinary N-out (ma N/kg) |
Faecal N-out (ma N/kg) |
N Balance (ma N/kg) |
Protein Digestibility (%) |
| 3 | 72 3 | 37 ± 1 | 172 ± 9 | 141 ± 27 | 23 ± 7 | - 2 ± 35 | 87 |
| 6 | 67 0 | 38 ± 1 | 190 ± 8 | 151 ± 17 | 34 ± 4 | 1 ± 8 | 81 |
| 1 | 60 6 | 39 ± 2 | 170 ± 1 1 | 140 ± 29 | 23 ± 3 | 5 ± 30 | 86 |
| 4 | 58.0 | 42 ± 3 | 173 ± 12 | 128 ± 28 | 34 ± 8 | 5 ± 22 | 80 |
| 5 | 578 | 42 ± 2 | 213 ± 11 | 174 ± 21 | 41 ± 11 | -8 ± 21 | 81 |
| 2 | 54.9 | 44 ± 2 | 218 ±11 | 174 ± 24 | 34 ± 6 | 6 ± 24 | 84 |
TABLE 6. Experimental Design
| Period | Dietary Condition |
| I (52 days) | Subjects 1, 2, 3 consuming ordinary protein levels. Subjects 4, 5, 6 consuming 15 per cent less protein than in ordinary diet. |
| II (49 days) | Subjects 1, 2. 3 consuming 15 per cent less protein than in ordinary diet. Subjects 4, 5 6 consuming ordinary protein levels |
| III (53 days) | Protein levels for each subject were selected according to data of experimental periods I and II. |
Kraisid Tontisirin, Kallaya Thongprasert and Area Valyasevi
Faculty of Medicine, Ramathibodi Hospital and Institute of Nutrition, Mahidot University, Bangkok, Thailand
Objectives
Recently, the N-balance response method has been used to determine the protein requirements of adult Thai men. The mean + SD requirement for egg protein of the subject was 0.81 + 0.05 g/kg/day. Since this value was obtained from a short-term N-balance study in a metabolic unit under a well-defined, experimental condition, further long-term testing under free-living conditions was required. Therefore, the objective of this study was to evaluate the adequacy of the recommended level of protein intake in adult village men consuming their habitual diet for a period of three months.
Experimental Design
Environment
The entire study was conducted during the period from mid-November 1980 to the end of February 1981 at Rai-Tai village in Ubon Province, north-east Thailand. The temperatures were 25.3 ± 0.6°, 22.8 ± 0.6°, 25.4 ± 1.2°C, and 28.3 ± 2.2°C during the months of November, December, January, and February, respectively. This was the cool season.
Subjects
Twelve adult village men participated in the study. They were apparently in good health, based on medical history, physical examination, complete routine blood count, urinalysis, and chest X-ray. Stool examinations were done before the beginning of the study and at the end of each month. Any ova or parasites found were recorded.
TABLE 1. Initial Characteristics of 12 Adult Thai Village Men
Subject |
Age (yrs) |
Weight (kg) |
Height (cm) |
LMAC (cm) |
LMAMC (cm) |
Skin-fold Thickness (mm) |
|
Tricep |
Subscapular |
||||||
| 1B.B. | 26 | 58.0 | 159.2 | 27.5 | 23.7 | 12.2 | 13.8 |
| 2 S.B. | 21 | 50.1 | 159.0 | 25.0 | 22.2 | 9.0 | 12.8 |
| 3 P.N. | 26 | 46.6 | 161.7 | 24.7 | 23.2 | 4.6 | 10.8 |
| 4 S.V. | 19 | 56.9 | 166.0 | 27.0 | 24.7 | 7.4 | 10.4 |
| 5 K.P. | 19 | 55.3 | 170.0 | 25.0 | 23.4 | 5.2 | 9.2 |
| 6 N.T. | 23 | 57.4 | 165.4 | 27.3 | 25.2 | 6.6 | 11.8 |
| 7 P.S. | 24 | 46.2 | 157.8 | 24.2 | 22.6 | 5.0 | 9.8 |
| 8 S.D. | 19 | 58.0 | 1650 | 28.0 | 26.0 | 62 | 10.2 |
| 9 P.T. | 19 | 45.6 | 159.0 | 23.3 | 21.2 | 6.8 | 7.4 |
| 10 P.P. | 21 | 50.5 | 156.4 | 26.9 | 25.1 | 5.6 | 9.4 |
| 11 S.P. | 19 | 51.6 | 164.5 | 24.0 | 21.6 | 7.7 | 7.6 |
| 12 T.C. | 19 | 54.3 | 165.6 | 25.7 | 21.2 | 7.8 | 10.2 |
| Mean | 21 | 52.5 | 162.5 | 25.7 | 23.5 | 7.0 | 10 3 |
| SD | 2.7 | 4.7 | 4.2 | 1.6 | 1.5 | 2.1 | 1.9 |
The initial characteristics of the subjects are shown in table 1. The mean age was 21.1 years, weight 52.5 kg, height 162.5 cm. left mid-arm circumference 25.7 cm, and left mid-arm muscle circumference 23.5 cm. They were quite lean, as indicated by the thin tricep and subscapular skinfold thickness values of 7.0 and 10.3 mm, respectively.
Diets
The subjects were given a five-day menu of their usual diets throughout the study. The major components of the diet consisted of sticky rice, fish, papaya salad, green leafy vegetables, bamboo shoots, and pumpkin.
Initially the diets were calculated to provide an energy intake of approximately 45 to 50 kcal/kg/day. A protein intake of 0.81 g/kg/day was provided by rice and fish, with a ratio of 70:30. However, the subjects were allowed an ad libitum rice intake, while other protein sources of the diet were controlled. Therefore, the actual mean energy intake was decreased from 62 to 51 kcal/kg/day and protein intake varied from 1.31 to 1.07 g/kp/day during the three-month study. The actual ratio of protein intake provided by rice and fish was about 80:20. Reported energy intakes correspond to net values obtained by food-bomb calorimetry minus faecal energy loss as measured by bomb calorimetry minus faecal energy loss as measured by bomb calorimetry.
TABLE 2. Diet Record of Subject B.B. from Day 1 to Day 5
| Ingredients | Amount (g) | Energy (kcal) | Protein (g) | Fat (g) | |
| Day 1 | Rice (raw) | 763.0 | 2,783.00 | 44.41 | 4 73 |
| Dried fish | 17.7 | 88.26 | 13.92 | 1.37 | |
| Mixed vegetables | - | 103.30 | 3.53 | 0.36 | |
| Soy-bean oil | 1 4.5 | 130.50 | - | 14.50 | |
| Fermented fish sauce | 20.8 | 18.60 | 0.72 | 0.11 | |
| Total | 3,124.00 | 62.58 | 21.10 | ||
| Dist. (%) | 8.00 | 6.10 | |||
| Day 2 | Rice (raw) | 808.8 | 2,950.00 | 47.07 | 5.01 |
| Dried fish | 17.7 | 88.26 | 13.92 | 1 37 | |
| Mixed vegetables | - | 97.20 | 3.17 | 0.62 | |
| Soy-bean oil | 14.5 | 130.50 | - | 14.50 | |
| Fermented fish sauce | 20.8 | 18.60 | 0.72 | 0.11 | |
| Total | 3,285.00 | 64.88 | 21.61 | ||
| Dist. (%) | 8.00 | 6.00 | |||
| Day 3 | Rice (raw) | 762.6 | 2,781.00 | 44.38 | 4.73 |
| Fresh fish | 73.4 | 80.01 | 13.92 | 0.76 | |
| Mixed vegetables | - | 79.40 | 3.33 | 0.40 | |
| Soy-bean oil | 14.5 | 130.50 | - | 14.50 | |
| Fermented fish sauce | 20.8 | 18.60 | 0.72 | 0.11 | |
| Total | 3,040.00 | 62.33 | 20.50 | ||
| Dist. (%) | 8.20 | 6.10 | |||
| Day 4 | Rice (raw) | 778.3 | 2,838.00 | 45.30 | 4.83 |
| Dried fish | 17.7 | 88.26 | 13.92 | 1.37 | |
| Mixed vegetables | - | 128.50 | 4.52 | 0.41 | |
| Soy-bean oil | 1 4,5 | 130.50 | - | 14 50 | |
| Fermented fish sauce | 20.8 | 18.60 | 0.72 | 0.11 | |
| Total | 3,204.00 | 64.46 | 21 22 | ||
| Dist. (%) | 8.00 | 6.00 | |||
| Day 5 | Rice (raw) | 694.7 | 2,534.00 | 40.43 | 4.37 |
| Dried fish | 17.7 | 88.26 | 13.92 | 1.37 | |
| Mixed | - | 72.20 | 3.44 | 0.45 | |
| vegetables | 14.5 | 130.50 | - | 14 50 | |
| Soy-bean oil | |||||
| Fermented fish sauce | 20.8 | 18.60 | 0.72 | 0.11 | |
| Total | 2,844.00 | 58.51 | 20.80 | ||
| Dist. (%) | 8 20 | 6.60 |