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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

Conclusions and comments

1. An all-vegetable diet can fulfil the protein requirements of pre school children when black beans and corn provide about 0.7 and 0.95 9 protein/kg/day, respectively. This is true when the children are physically active and net dietary energy intakes range between 71 and 90 kcal/kg/day.

2. Within those ranges the level of energy intake did not affect nitrogen balance. The amounts of nitrogen retained by the children were greater than those that have been estimated to allow adequate growth, suggesting that the diets used in this investigation provided more protein than required. Therefore, it may be that the amounts of protein provided by the diet surpassed requirements to a point where the protein-sparing effect of energy was obscured, and it is conceivable that the amounts of dietary energy used might have influenced nitrogen balance if the protein intake had been closer to the requirement level.

3. Nitrogen retentions were high even though the "true" protein digestibilities were low, corresponding to an average of 1.14 9 protein absorbed/kg/day (1.73 g/kg with a digestibility of 66 per cent). Nitrogen digestibility was lower than we have observed in other studies using similar diets (67 to 83 per cent), and it seemed to be related to large faecal volumes that averaged 197 g/day in this study. The apparent absorption of energy (88 per cent) differed less from our other investigations (89 to 92 per cent).

4. Diets of the type used in this study failed to fulfil pre-school children's energy requirements unless their energy density was increased. At least 10 per cent additional energy had to be added to the diets as vegetable oil to ensure adequate weight gains. This provided an average of 82 net kcal/kg/day.

5. There were no changes in weight gain when the net dietary energy decreased from 90 to 82 kcal/kg/day. However, this change was accompanied by a decrease in total energy expenditure, although no changes in physical activity patterns were noticed, and energy "balance" (defined as intake minus faecal, urinary, and sweat losses, and minus total energy expenditure) remained constant. Basal energy expenditure and the energy lost through excrete also remained constant. The children seemed to adjust to the initial decrease in intake by a decrease in physical activity or by a greater efficiency in performance (i.e., spending less energy to do the same things) and continued to gain weight at an adequate rate. These findings could also indicate that, within certain limits, the children avoid becoming obese by increasing their energy expenditure when there is an excessive dietary energy intake. When the net dietary intake was further decreased to 71 kcal/kg/day, energy expenditure did not diminish any more and the children lost or reduced their weight gains. Therefore, we conclude that a net dietary intake of 71 kcal/kg/day was insufficient and the children could not compensate for this low intake by a decrease in physical activity under the experimental conditions that prevailed.


This research was made possible through the financial assistance of the World Health Organization, as part of its support of a series of investigations related to protein and energy requirements of children, and through the United Nations University World Hunger Programme.