Contents - Previous - Next
This is the old United Nations University website. Visit the new site at http://unu.edu
Food and Nutrition Research Center, National Science Development Board, Manila, Philippines
To determine the protein requirements of young children on a diet based mainly on rice gruel and mung bean when dietary energy is not a limiting factor.
Tropical climate; temperature 25° to 29° C; relative humidity, 50 to 58 per cent.
Five apparently healthy male Filipino children 22 to 29 months old participated in the study. They were recruited from a welfare institution. All children had just been subjects in another metabolic study. Their characteristics are shown in table 1. Using body weight as a parameter. three of the children were classified as normal by Philippine standards 11); the other two subjects were in the upper limit of firstdegree malnutrition. Using the same standards, all subjects were below their ideal height for age by 5 to 9.7 cm. Blood analyses indicated good-to-borderline levels.
The diets were essentially based on rice and mung bean with added fruits and vegetables low in protein content (table 2). The diets were calculated to provide 100 kcal/kg body weight/day using proximate composition and Atwater factors. A blend of coconut-corn oil (50:50) and the small amounts of fat from other foods provided about 30 per cent of the energy intake. One-third of the dietary protein was provided by mung bean.
TABLE 1. Characteristics of Subjects
cation by weight
a. Creatinine height index.
c First-degree undernourished or - 10 % underweight.
TABLE 2. Diet Composition Per 1,000 kcala
|Coconut-corn oil (1:1)||31.8||280||-||31.80|
a Sample diet for a 10 kg child at 100 kcal/kg and at a level of 200 mg N/kg body weight (1 25 9 protein)
Four levels of dietary protein were given to each subject. Adjustment in protein level was done by substituting protein calories with starchy roots, fruits, or mung-bean starch. Two children (R.D. and P.D.) followed the descending design, that is, starting from the highest level followed by the other levels in 0.25 9 decrements; the three other children followed the ascending design.
Vitamin and mineral supplements given daily provided the following: vitamin A (3,000 IU), 0,9 mg; vitamin D2 (400 IU), 10 mg; vitamin C, 50 mg; thiamine, 1.5 mg; riboflavin, 1.2 mg; pyridoxine, 1 mg; vitamin B12, 3 mg; niacinaminde, 10 mg; iron, 3 mg; iodine, 75 mg; calcium, 40 mg; phosphorus, 43 mg; magnesium, 3 mg; manganese, 0.5 mg; zinc, 3.071 mg; choline, 5 mg; dexpanthenol, 5 mg and inositol, 5 mg. In addition, 2 teaspoons of Cetrin were given daily. Each 30 ml contains 250 mg vitamin C.
Each dietary protein level lasted for seven days with a three-day break period between two experimental levels. During this period the subjects were fed the regular diet (250 mg N/kg/day).
Indicators and Measurements
Apparent N balance was calculated during the last four days of each seven-day feeding period at each N level for each child. Aliquots of daily urine excretions, two-day pooled faecal specimens, and diets were analysed by the macro-Kjeldahl method.
Apparent N absorption was calculated from data on dietary and faecal nitrogen. Apparent N retention was estimated by subtracting urinary and faecal nitrogen from total nitrogen intake and dividing this by the total intake. Biological value was estimated by dividing the percentage of N retained by the corresponding apparent absorption.
This was calculated as the zero balance intercept from the regression equation of true N balance (y) on N intake (x), pooling all data points (2). The safe level of protein intake was calculated from the upper 95 per cent confidence band.
An allowance of 10 mg N/kg/day was made for integumental and miscellaneous N losses to estimate the true N balance.
Urinary Creatinine and Urea Nitrogen
Determined by Folin's method and a modified Van Slyke and Cullen's method, respectively.
Body weight was taken daily every morning before breakfast, post-voiding, with minimal clothing. The following measurements were obtained on day four and day 10 of each dietary period; height, arm, waist, chest and tricipetal and subscapular skinfold thicknesses.
N balance and Absorption
The summary of individual mean nitrogen and energy intakes, apparent N balance, N absorption, and biological values are presented in table 3. At the lowest level of nitrogen intake (1 9 protein/kg), two subjects were in negative nitrogen balance, but when these were corrected for sweat nitrogen (10 mg N/kg), all subjects except one remained positive. At higher levels all the subjects were in positive balance.
N absorption, N retention, and biological values decreased as levels of N in the diet were lowered. The low percentage of N absorption may be accounted for by the large amounts of N lost in faeces.
By regression analysis of true N balance y = - 120. + 0.751 x (r = 0.8604). The mean N requirement (PRm) was calculated as 160.9 mg N, or 1.0 9 protein/kg/day. The safe level of intake for 97.5 per cent of the population was calculated as 221.9 mg N or 1.39 9 protein/kg/day.
Changes in body weights of the subjects for each experimental period are also shown in table 3. Although energy intake was kept constant, the subjects lost body weight on N intake levels of 200 mg to 280 mg but gained at the 160 mg N/kg body-weight intake level. There was, however, one subject (P.D.) who lost weight at this level, which could not be explained from his daily record during this period.
The relationship of increased weight gain with a higher percentage of PE does not seem to apply to the diets given in this study. Other body measurements did not show a consistent pattern when correlated with changes in body weight.
Conclusions and Comments
The mean protein requirement of young children obtained when given rice and mung bean as the main sources of protein was 1 g/kg/day, and the safe level of intake was 1.39 g/kg/day. This requirement is much higher than a comparative study on a rice-fish diet where PRm was 0.7 g/kg/day and the safe level was 1 g/kg/day.
TABLE 3. Nitrogen and Energy Intakes, Nitrogen Balance, Digestibility, Biological Value and Changes in Body Weights at Each Level of Nitrogen Intake
|Mean Daily Energy Intake||Mean Daily N Excretion||Balance
|151||99||3.8||81||91||- 28||53.8||12.7||0.0||+ 12|
|146||98||3.7||61||87||- 2||40.4||0.0||0.0||- 2|
TABLE 4 Comparison of Results of this Study with the Study Carried Out by Roxas et al. (3)
|Roxas Study||This Study|
of children, months
Energy intake, kcal/kg body weight
|Number of children||4||5||5||5|
|N intake (mg/kg body weight)||197||235||200||243|
|Faecal N (mg/kg body weight)||65||56||85||92|
|Urinary N (mg/kg body weight)||90||124||67||81|
|N retention (mg/kg body weight)||42||55||44||67|
|Apparent N digestibility (%)||67||76||57||62|
|Apparent N retention (%)||22||23||22||28|
|Changes in body weight (g/day)||3||10 5||- 5||- 24|
Losses in body weight of the subjects when N levels in the diet were 200 mg and above could have been caused by one or several of the following factors.
1. The use of whole bean in the diet. In a comparable study reported by Roxas et al. (3), the mung beans used were dehulled and pulverized. A comparison of the results of the Roxas study with this study is shown in table 4.
At comparable levels of N intake, faecal losses in this study are higher, N digestibilities are lower, and subjects lost more weight at 241 mg N intake than at 198 mg N. On the other hand, in Roxas' study the weight gains observed were adequate at a level of 197 mg N/kg/day and increased at the higher N intake.
2. The dietary fibre of the rice/mung-bean diet used in this study is most likely higher than the rice/dehulled mung-bean diet used by Roxas. In a study on the Guatemalan diet reported by Calloway and Kretsch (4), the high dietary fibre of the black-bean and lime-treated tortillas reduced the digestibility of energy and protein by 3 to 4 per cent. Similar losses in energy could have occurred with the rice-mung bean diet in this study.
3. The chemistry department of IRRI (International Rice Research Institute) has reported the presence of poorly digested protein from cooked milled rice, with the major fraction having MW 16,000 (5).
4. The presence of trypsin inhibitor in mung bean cannot be discounted. This may explain the poor utilization of nitrogen as levels are increased. In the diet used by Roxas, the dehulling of the bean made use of dry heat that could have destroyed any trypsin inhibitor.
The results of this study could be an important consideration in the planning of ricebased diets or weaning foods for young children.
1. Boundaries of Classification by Weight of Filipino Children /Males and Females Combined) Ages 18 Months to 72 Months (FNRI Publication No. 137A, 1971).
2. W.M. Rand, N.S. Scrimshaw. and V.R. Young. "Determination of Protein Allowances in Human Adults from Nitrogen Balance Data," Am. J. Clin. Nutr, 30:1129-1134 (1977).
3 B.V. Roxas, C.L. Intengan, and B.O. Juliano, "Protein Content of Milled Rice and Nitrogen Retention in Preschool Children Fed Rice-Mung-bean Diets." Nutr. Rep. Int., 11: 393 (1975)
4. D.H Calloway and M.J. Kretsch, "Protein and Energy Utilization in Men Given a Rural Guatemalan Diet and Egg Formulas With and Without Added Oat Bran, Am. J. Clin. Nutr, 31: 1118-1126 (1918).
5. B.V. Roxas, C L. Intengan, and B.O. Juliano, Annual Report (Grant No. AID/D SAN-G-0157. Agricultural/Nutrition Branch, AID, Washington D.C.).
Kraisid Tontisirin, Nissawan Ajmanwra, and Aree Valyasevi
Institute of Nutrition, c/d Ramathibodi Hospital. Mahidol University, Bangkok. Thailand
Summary of Short-term Study Phase 1 as Background Information
Nine children, aged 9 to 36 months, weighing 8.1 to 11.1 kg, and living in a metabolic unit, were given usual Thai weaning diets at three levels of energy intake varying from 87 to 118 kcal/kg/day. These diets consisted of rice, fish, and bananas. The protein intake was fixed at the "safe level," 1.7 g/kg/day, derived from rice and fish in a ratio of 70:30, and having an amino-acid score of 94.8 with assumed digestibility of 93 per cent.
Each level of energy intake was fed for seven days: the first four days for adaptation to a new intake level and the last three for balance studies. There was a four-day resting period between each treatment. Fat intake was kept constant throughout the study at about 10 per cent of energy intake. Vitamin and mineral supplements were given daily.
The adequacy of protein intake was evaluated by measuring N retention and weight gain. Other measurements included fat and energy absorption; blood constituents were also measured. A summary of the data in study phase 1 is shown in tables 1 and 2.
At the lowest level of energy intake, 87 kcal/kg/day, apparent N retention and weight gain were quite low, being 43.7 mg N/kg/day and 3.5 g/day respectively. At the two higher levels of energy intake (100 and 118 kcal/kg/day), apparent N retention was greater than 60 mg/kg/day and weight gain was about 20 g/day or more.
Biological value (BV) and net protein utilization (NPU) were clearly affected by the changes in energy intake. They decreased significantly with decreased energy intake. N absorption and digestibility, however, were not affected by changes in energy intake.
The results from this study suggest that at the "safe level" of protein intake, as recommended by FAO/WHO in 1973, the usual Thai weaning food provides adequate protein for the needs of young children if energy intake is supplied at 100 kcal/kg/day or higher.
TABLE 1 Summary of Study Phase 1 on the Effects of Varying Energy Intakes on the Adequacy of the Safe Level of Protein Intake in Young Children
|Energy intake (kcal/kg/day)|
|Number of children||9||9||7|
|Age (months)||21.6 ± 2.8|
|Protein intake (g/kg/day)||1.7 ±0.01 a||1.7 ± 0.04||1.7 ±0.`05|
|Fat intake (% of energy)||11.2 ± 0.6||10 1 ± 0.2||10.1 ±0.5|
|Fat absorption (% of intake)||90.2 ± 1.0||91 4 ± 1.2||91.0 ±1.0|
|Energy absorption (% of intake)||8.5 ±0.4||6 7 ± 0.6||7.1 ±0.6|
|Weight gain (g/day)||3.5 ±6.9||20 3 ± 5.9||53.8 ±7.3|
|N balance (mg/kg/day)|
|N intake||271.2 ± 2.3||276. 4 ± 5.8||277.0 ±7.4|
|Urinary N||116.2 ± 6.9||100.5±6.8||80.2 ±4.8|
|Faecal N||111.3 ± 8.9||106.2 ± 10.9||121.6 ± 11.2|
|Apparent N balance||43.7 ± 6.8||69.6 ±7.8||75.7 ±7.6|
|Urinary creatinine (mg/day)||140.7 ± 11.6||1506 ±6.8||144 6 ± 8.1|
|N absorption (% of intake)||58.9 ± 3.4||61 7 ±3.6||56 5 ±3.5|
|Digestibility (%)||66.7 ± 3.4||69.4 ±3.7||64 1 ±3.6|
|BV (%)||61.3 ± 4.1||71.1 ±2.7||80 1 ±2.5|
|NPU (%)||40.5 ± 2.7||49.2 ±3.0||51 3 ±3.1|
a Mean ± SE
TABLE 2. Summary of Blood Constituents in Study Phase 1
|Initial||Energy intake (kcal/kg/day)|
|BUN (mg/dl)||8 7 ± 0 7 a||6 1 ± 0.6||5 4 ± 0 4||3 7 ± 0 5|
|Albumin (g/dl)||4 2 ± 0.06||4.0 ± 0.08||4 1 ± 0 09||3 9 ± 0 06|
|Total protein (g/dl)||6 8 ± 0 2||6 6 ± 0.1||6 8 ± 0 1||6.4 ± 0.1|
|AST (SF units)||355 ± 44||373 ± 43||375 ± 1 5||438 ± 20|
|ALT (SF units)||14 1 ± 1 3||13.8 ± 2.3||15 7 ± 1.1||22 9 ± 1 3|
a Mean + SE
TABLE 3. Initial Characteristic of Six Young Male Children
(% of Thai standard)a
|Mean ± SE||9.7 ± 0.8||7.8 ± 0.3||67.9 ± 0.4||95.7 ± 2.0|
a From P Khanjanasthiti "The
Anthropometric Nutritional Classification of the Infants and
Preschool Children J Med Ass Thai., vol 60 Suppl 1 (1977)
Objective of Study Phase 2
The specific objective of this study was to determine whether a usual Thai weaning diet would provide adequate protein and energy for the needs of young children over a long-term period.
The entire study was conducted in a metabolic ward of Ramathibodi Hospital, Mahidol University. The subjects were under close nursing and medical care and were also provided with adequate play facilities.
Six normal, healthy, young male children aged 8-12 months were selected from an orphanage. They were studied after they had been rehabilitated for protein-energy malnutrition for eight weeks or longer and had reached normal weights for height. Their initial characteristics are shown in table 3. The means of age, weight and height were 9.7 months, 7.8 kg, and 67.9 cm, respectively. They were completely reexamined before the beginning of the study to ascertain that they were in good health.
TABLE 4. Proximate Analysis of Usual Thai Weaning Diet
|Nutrients||per 100 g|
The diets given to the children were largely based on rice and fresh-water fish, supplying protein in a ratio of 70:30 by weight. Fifty grams each of green leafy vegetables and ripe banana were also given daily. Fat intake was provided at a level of 10 per cent of energy intake. Neither vitamin nor mineral supplements were given to the children during the study. Table 4 shows the data for proximate analysis of the diets.
In order to maintain precision in dietary components, diets were prepared in advance for each month of dietary testing. The body weights of the subjects were taken into account for readjustments of protein and energy food contents.
Protein and energy intake levels were 1.7 g/kg/day and 100 kcal/kg/day, respectively. The usual Thai weaning diet is fed in three meals per day. with drinks containing sugar once or twice a day.
The entire study lasted for 120 days, or four months.
Figure 1 shows the experimental design of the study. The entire study was divided into four periods, with each period lasting for 30 days.
1. Diet samples - for each period, a one-day diet sample analysed twice a month for N, energy (bomb calorimetry), and fat.
2. Fasting blood samples were taken initially and at the end of each month for analyses of complete blood count, total serum protein, albumin, and urea N.
FIG. 1 Experimental Design for Long-term Study of Six Infants Given Usual Thai Weaning Food.
TABLE 5. Protein, Fat and Energy Intake of Six Infants Given Usual Thai Weaning Food for Four Months
|Protein Intake||Fat Intake|
|(% energy)||(g/kg/day)||(% energy)||(g/day)|
|Mean ± SE||99.2 ± 1.7||7.1 ± 0.1||1.8 ± 0.02||10.2 ± 0.4||8.7 ± 0.4|
|Mean ± SE||98.5 ± 2.4||7.1 ± 0.6||1.8 ± 0.04||9.8 ± 0.4||8.8 ± 0.4|
|Mean ± SE||94.1 ± 1.8||6.8 ± 0.3||1.7 ± 0.1||10.0 ± 0.4||8.8 ± 0.3|
|Mean ± SE||93.2 ± 2.8||6.4 ± 0.1||1.6 ± 0.1||9.4 ± 0.3||8.7 ± 0.4|
|Period 1 vs. 2||NS||NS||WS|
|Period 2 vs. 3||P < 0.025||P<0.05||NS|
|Period 3 vs. 4||NS||NS||NS|
|Period 1 vs. 4||NS||P < 0.05||NS|
TABLE 6. N Balance in Six Infants Given Usual Thai Weaning Food for Four Months
|N balance (mg/kg/day)|
|N intake||Urinary N||Faecal N||Apparent
|1||6||99.2±1.7||282.8± 7.5||92.3± 6.2||90.5±10.0||100.1± 8.4|
|2||6||98.5±2.4||287.3± 9.1||101.2± 6.8||101.6±5.6||84.5± 11.4|
|4||5||93.2±2.8||255.4± 4.3||123.1± 7.1||86.1 ± 3.2||46.1 ± 5.7|
|Period 1 vs. 2||NS||NS||NS||NS||NS|
|Period 2 vs. 3||P < 0.025||P < 0 05||NS||P < 0 05||NS|
|Period 3 vs 4||NS||NS||NS||NS||NS|
|Period 1 vs 4||NS||P < 0.05||P < 0 05||NS||P < 0.025|
3. 24-hour urine samples were collected during days 7, 14, 21, and 27 to 30 of each period for analyses of total N and creatinine (see fig. 1).
4. Three-day faecal collections were taken at the end of each period during days 27 to 30 of the month for analyses of N, energy, and fat.
5. Body weights were measured daily before breakfast, and other anthropometric measurements, including height, head, and left mid-arm circumference, and tricep skin-fold thickness, were measured every week.
The subjects were allowed normal activities, which included playing on the floor of the metabolic ward. Toys and mobile units were provided. Children were put on metabolic beds during the period of urine collection.
Contents - Previous - Next