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Level of Nutrient Intakes

Table 5 shows the daily energy, protein, and fat intakes of each subject during the four-month period. Energy intakes were close to 100 kcal/kg/day during the first and second months (periods 1 and 2). They were later decreased to 94 and 93 kcal/kg/day during the third and fourth month (periods 3 and 4), respectively. Protein intakes ranged from 1.5 to 1.9 g/kg/day, and fat intake was approximately 10 per cent of energy intake. The decreases in energy intake were mainly because of poor appetite of the subjects during the last month of the study (period 4).

TABLE 7. N balance (mg/kg/day) in Period 1 (First Month) of Six Infants Given Thai Weaning Food for Four Months

a. P < 0.025 as compared with D_27-30 of the corresponding period

TABLE 8. N Balance (mg/kg/day) in Period 2 (Second Month) of Six Infants Given Usual Thai Weaning Food for Four Months

a No statistical differences as compared with the values obtained during D_27-30

N Balance

Table 6 shows N-balance data during the four-month study period. The apparent N-balance values during periods 1 and 2. when the subjects received energy intakes of 100 kcal/kg/day. showed N retention of 84.5 to 100.1 mg N/kg/day. When energy intakes dropped to 93 or 94 kcal/kg/day, N retention ranged from 46 to 71 mg/kg/day as seen in periods 3 and 4.

TABLE 9. N Balance (mg/kg/day) in Period 3 (Third Month) of Six Infants Given Usual Thai Weaning Food for Four Months

a No statistical differences as compared with the values obtained during D_27-30

TABLE 10. N Balance (mg/kg/day) in Period 4 (Fourth Month) of Six Infants Given Usual Thai Weaning Food for Four months

a No statistical differences as compared with the values obtained during D_27-30

Tables 7 to 10 show the daily urinary N excretions and apparent N balance during days 7, 14 21, and 27 to 30 of each period. The data obtained from one-day urine collection were almost identical to those of a three-day urine collection. N retention during the first three months was generally 70 mg/kg/day or greater. However, during the last period of study. N retentions were about 43 to 53 mg/kg/day as shown in table 10.

TABLE 11. Protein Quality Indices of Usual Thai Weaning Food Given to Six Infants for Four Months

Statistical/ analysis:

FIG. 2. Correlation between Age of Infants (x) and BV (y) (___) and Age of Infants (x) and NPU (y) (- - -) Given Usual Thai Weaning Food for 4 Months.

FIG. 3. Protein Quality Indices in Six Infants Given Usual Thai Weaning Food for Four Months.

TABLE 12. N Balance and Weight Gain in Six Infants Given Usual Thai Weaning Food for Four Months

Protein Quality Indices

Table 11 and figures 2 and 3 show the protein-quality indices of the usual Thai food given to these six infants for four months. N absorptions as percentage of intake and digestibility were almost constant, being about 66 and 74 per cent respectively.

It is interesting that BV and NPU decreased steadily as the study progressed from the first to the fourth month. However, significant differences of BV and NPU were seen only in periods 1 and 4. Significant correlations were found between the age of the infants (x = month), and BV and NPU (y = percentage); as shown by the equations of y = 91.81-1.95x (P < 0.05) and y = 68.27-1.49x (P < 0.05), respectively.

Urinary Creatinine Excretion

Daily urinary creatinine excretions showed no significant differences whether urine samples were collected for one day or for three days of each period. There were also no differences in creatinine values when compared between the periods of the study.

Weight Gain

Tables 12 and 13 show-weight gain and apparent N balance of the six infants fed the usual Thai weaning food for four months. All infants except one (A.B.) gained weight at a level of 9 g/day during periods 1 and 2. During subsequent periods, subject A.B. and L.S. did not gain weight as well as the other subjects. N retention data of subject A.B., however, was 61 mg/kg/day or greater during periods 1-3, and 30.4 mg/kg/day during period 4.

The means of weight gain in all study periods were greater than 7.6 g/day, as shown in table 13.

Figures 4 to 9 show details of body weight, energy intake, N intake, and N balance of the individual subjects.

Fat and Energy Absorption

Fat and energy absorption ranged from 93.1 to 95 and 93 to 94.2 per cent of intakes, respectively, as shown in table 14.

Other Measurements

The measurements of haematocrit, serum total protein, albumin, and urea nitrogen at the beginning and end of each month were within normal ranges, and no significant changes were observed during the entire period of study.

TABLE 13. Summary of N Balance and Weight Gain in Six Infants Given Usual Thai Weaning Food for Four Months

Statistical analysis:

TABLE 14. Fat and Energy Absorption in Six Infants Given Usual Thai Weaning Food for Four Months

Conclusions and Comments

The results from a short-term balance study during phase 1 indicated that the safe level of protein intake as recommended by FAD/WHO in 1973 was adequate if energy intake was 100 kcal or higher per kg per day. The metabolic period in phase 1 lasted for only seven days. Therefore, it was the objective of the phase 2 study to conduct a long-term feeding study on six infants aged 8 to 12 months given the usual Thai diet for four months. The level of protein and energy intakes were 1.7 g/kg/day and 100 kcal/kg/day, respectively. These diets consisted mainly of rice and fish in a ratio of 70:30 by weight of protein.

The results from this study, based on N retention, weight gain, observation of physical activities, and measurements of blood constituents. indicated that the intake of protein at this "safe level" was also adequate for a long-term period if energy intake were supplied at about 100 kcal or higher/kg/day.

FIG. 4 Long-term Study of Infant O.M. Given Thai Habitual Weaning Food.

FIG. 5. Long-term Study of Infant A B. Given Thai Habitual Weaning Food.

FIG. 6. Long-term Study of Infant N.N. Given Thai Habitual Weaning Food.

FIG. 7 Long-term Study of Infant D S. Given Thai Habitual Weaning Food.

FIG. 8. Long-term Study of Infant L.S. Given Thai Habitual Weaning Food.

FIG. 9. Long-term Study of Infant K.P. Given Thai Habitual Weaning Food.

One subject (A.B.) did not gain weight satisfactorily because he was overly active. His N-retention data were still quite satisfactory at over 60 mg/kg/day, when energy intakes were adequate. However, when energy intake was inadequate because of poor appetite, N retention decreased to around 30 to 40 mg N/kg/day.

The measurements of one-day urinary N excretion at the end of each week yielded data identical to those of a three-day urinary N excretion. The data provided a better understanding of weekly N retention of infants as correlated to energy and protein intakes and weight gains.

Correlations were also found between decreased BV and NPU with increases in age of the infants. These findings have indicated that younger infants can utilize protein more efficiently than older infants.

The overall results from this long-term study confirmed the previous phase 1 short-term study that the "safe level" or recommended level of protein intake for one-year-old children was adequate provided that energy intake was 100 kcal or higher per kilogram per day.

Acknowledgements

This study was supported by research funds from the Danish International Development Agency (DANIDA) through FAO and WHO. The authors would like to thank the nursing and metabolic kitchen staffs of the clinical research ward, Ramathibodi Hospital, for their assistance during the study.

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