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close this bookProtein-Energy Requirements of Developing Countries: Evaluation of New Data (UNU, 1981, 268 p.)
close this folderProtein-energy requirements-children
close this folderEnergy requirements of pre-school children and effects of varying energy intakes on protein metabolism
View the document(introduction...)
View the documentObjectives
View the documentExperimental details
View the documentSummary of main results
View the documentConclusions and comments

Summary of main results

1. Dietary Intakes
Table 5 gives the average intakes of dietary energy and protein for each child and for the group.

2. Energy and Protein Absorption
Table 6 gives the apparent energy absorption of each child for all levels of energy intake. The overall average absorption was 88 6 per cent. With gross intakes of 100, 92, and 83 kcal/kg, apparent absorptions were, respectively, 91 6 per cent, 80 7 per cent, and 85 4 per cent. Although the mean values decreased with decreasing levels of intake, they were not different from each other.

Table 6 also gives the "true" and apparent digestibilities of nitrogen (i.e., with or without correction for endogenous faecal nitrogen). The average apparent digestibility was 59 6 per cent for all levels of energy intake. With net energy intakes of 90, 82, and 71 kcal/kg/day, apparent nitrogen digestibility was 56 7 per cent, 59 6 percent, and 62 9 per cent, respectively.

TABLE 6. Absorption of Energy and of Nitrogen as a Percentage of the Amounts Ingested (Mean of all Levels of Dietary Energy)

  Energy absorption,

Nitrogen digestibility

Patient apparent apparent "true"* *
379 94 3* 64 4 71 4
387 88 4 59 11 66 11
388 84 9 60 3 67 3
390 85 4 61 9 68 9
394 88 7 47 4 54 4
395 87 5 65 7 73 7
Average 88 6 59 9 66 9

* Mean + standard deviation.
** Assuming obligatory faecal losses of 20 mg N/kg/day.

These values were not different from each other. "True" digestibilities were higher by about 7 per cent of nitrogen intake. One child (394) consistently had low nitrogen digestibilities. If his results were not included in the analysis, the average apparent digestibility for the other five children at all levels of energy intake would be 62 4 per cent, and with the three levels of net dietary energy they would be 58 6, 61 3, and 66 8 per cent. These values do not differ from each other.

There was no association between the apparent absorptions of energy and protein (r= 0.173).

3. Nitrogen Balance
The values of the two four-day balance periods at each dietary energy level were averaged for each child. Table 7 gives the nitrogen balance data of five children at each level of energy intake. There were no differences among the three dietary energy intakes. Child 387 retained 54.1, 95.7, and 43.6 mg N/kg/day when he ingested 106, 96, and 90 kcal/kg/day, respectively. The mean and standard deviations of the seven balances performed on him were 61.5 31.8 mg N/kg/day.

TABLE 7. Nitrogen Balance (Nitrogen Intake-Urinary Nitrogen- Faecal Nitrogen-5 mg/kg/day) Expressed as mg N/kg/day

Child

Net dietary energy (kcal/kg/day)

Mean and S D of 6 balances*
90 82 71
379 76.6 51.4 59.9 62.6 18.7
388 59.9 88.3 60.8 69.6 20.6
390 51.6 53.1 86.7 63.8 18.1
394 52.5 50.9 49.9 51.1 14.6
395 78.1 69.4 66.0 72.2 9.2
Average 63.7 11.5 58.0 6.8 64.9 15.2  
(n= 10)*  

* Two balance periods with each level of energy intake.

4. Energy Expenditure
Table 8 gives the energy expended by five children at each of the three levels of dietary energy. The children spent more energy in physical activity with the highest level of intake (p < 0.05); there was no difference between the two lower levels of intake. The nurses and the investigators, however, did not notice any changes in the children's behaviour or in the pattern and intensity of their activities throughout the study. The sixth child (387) also expended more energy when he had the highest intake. His daily expenditure with net dietary intakes of 90,106, 96, and 90 kcal/kg were 80.4, 90.4, 73.4, and 78.9 kcal/kg, respectively.

5. Energy Balance
Table 8 also gives the energy balance of the children. There were no differences in energy balance with the different levels of dietary energy intake. The corresponding figures for child 387 were 9, 14, 19, and 5 kcal/kg/day with net dietary energy intakes of 90, 106, 96, and 90 kcal/kg/day, respectively.

6. Anthropometry and Growth
The only consistent anthropometric change was a decrease in bodyweight gain with the net dietary energy intake of 71 kcal/kg/day. Weight gains calculated in five children by regression analysis during the 40 days at each level of energy intake were (mean S.D.) 10.7 4.8, 11.4 3.4, and 0.6 4.4 g/day for 90, 82, and 71 kcal/kg/ day, respectively. Paired comparisons confirmed that the last value differed from the preceding two (p < 0.05 and <0.01), respectively.

TABLE 8. Total Daily Energy Expenditure and Energy Balance (kcal/kg/day)*

Net dietary energy (kcal/kg/day)

Patient

90**

82

71

 

exp.

bal.

exp.

bal.

exp.

bal.

379

104.0

- 11

89.8

- 3

81.6

- 7

388

84.8

7

76.0

4

63.3

5

390

77.8

0

77.8

- 4

72.0

- 10

394

93.5

- 6

65.6

22

65.6

3

395

85.2

- 3

69.7

13

74.9

- 3

mean

89.1***

- 3

75.8

6

71.5

- 2

S.D.

9.0

6

8.3

10

6.5

6

* Energy expenditure was calculated from heart rate and the corresponding heart-range-energyexpenditure relationship between 5 a.m. and 8 p.m., and from basal energy expenditure during the remaining 9 hours. Energy balance was calculated from energy intake {bomb calorimetry! —faecal energy (bomb calorimetry)—urine losses 15 kcal/g urinary nitrogen)—sweat losses 18 kcal/g sweat nitrogen = approx. 0.1 kcal/kg/day) — energy expenditure (as described above).
** Dietary-faecal energy, measured by bomb calorimetry.
*** Differs from the two other levels of intake, p < 0.025.

The sixth child (E.G., no. 387) lost 2 to 3 g/day with intakes of 90 and 82 kcal/kg/day. With 106 and 96 kcal/kg/day he gained 25 and 13 g/day, respectively, and only 3 g/day when he again received 90 kcal/kg/day.

The level of dietary energy did not affect growth in terms of height. Three children showed a continuous tendency to catch up, regardless of the amounts of energy intake.

7. Other Biochemical Measurements
Fluctuations within normal ranges were observed, without relation to the amounts of dietary energy intake.