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close this bookProtein-Energy Requirements of Developing Countries: Evaluation of New Data (UNU, 1981, 268 p.)
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View the documentStatistical considerations in the estimation of protein requirements
View the documentA summary analysis of the nitrogen-balance data
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View the documentProtein requirements for adults
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close this folderA note on energy utilization and its efficiency
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close this folderResearch papers: Protein requirements-adults, standard protocols
close this folderCapacity of the Chilean mixed diet to meet the protein and energy requirements of young adult males
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close this folderProtein requirements for young Colombian adults consuming local diets containing primarily animal or vegetable protein
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close this folderProtein requirements of young Chinese male adults for ordinary Chinese
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close this folderProtein requirements of young male adults with a rural Mexican diet
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close this folderThe evaluation of soy protein isolate alone and in combination with fish in adult Japanese men
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close this folderProtein requirements of adult Thai males
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close this folderEvaluation of the nutritive value of a rice-and-bean-based diet for agricultural migrant workers in Brazil
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close this folderProtein requirements-adults, other protocols
close this folderProtein quality of rice-and-bean diets with or without protein and energy supplements to estimate protein requirements in young adult humans
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close this folderProtein needs of young adult men fed common beans (phaseolus vulgaris) in combination with starch, plantain, maize, or rice
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close this folderObligatory nitrogen losses-adults
close this folderObligatory urinary and faecal nitrogen losses in young Chilean men fed two levels of dietary energy intake
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close this folderObligatory nitrogen losses of adult Thai males
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close this folderNitrogen absorption-adults
close this folderProtein absorption of adult men with intestinal helminthic parasites
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close this folderAbsorptive capacity of adult Guatemalan rural males living under different conditions of sanitation
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close this folderStudies of energy intakes, expenditures, and requirements in China
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close this folderObligatory and integumental nitrogen losses - children
close this folderObligatory nitrogen losses and factorial calculations of protein requirements of pre-school children
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close this folderIntegumental nitrogen losses of pre-school children with different levels and sources of dietary protein intake
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View the documentThe protein requirements of normal infants at the age of about one year: maintenance nitrogen requirements and obligatory nitrogen losses
close this folderProtein requirements-children
close this folderProtein requirements of Filipino children 20 to 29 months old consuming local diets
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close this folderProtein requirements of pre-school children: milk and soybean protein isolate
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close this folderProtein absorption of pre-school children with intestinal helminth parasites
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close this folderUse of corn-bean mixtures to satisfy protein and energy requirements of preschool children
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close this folderProtein-energy requirements-children
close this folderCapacity of habitual Guatemalan diets to satisfy protein requirements of pre-school children with adequate dietary energy intakes
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close this folderEnergy requirements of pre-school children and effects of varying energy intakes on protein metabolism
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close this folderRecommended dietary energy intakes for the first six months of life
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close this folderProtein-energy requirements-adults
close this folderInterrelationships between effects of protein and energy intakes on nitrogen utilization in adult men
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close this folderRecommended dietary amounts of energy for pregnancy and lactation in the United Kingdom
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Conclusions and comments

  1. The energy intake of women did not increase during pregnancy, and it was comparable to that of nonpregnant and non-(actating Cambridge women of similar age and social background: 2,029 392 kcal/day (Nelson et al., unpublished).
  2. In spite of these low intakes, mean weight gain during pregnancy coincided with the conventional standard of 12.5 kg. Mean birth weight was also normal, as was the weight retained by the mothers after parturition and hence the estimation of their energy stores for lactation.
  3. Since the pregnant women were not demonstrably less active, it would appear that they must have been able to satisfy at least part of the additional needs of pregnancy by subtle changes in activity or by an enhanced efficiency of metabolism.
  4. Milk outputs did not increase with dietary intakes above 2,000 kcal per day, but they decreased with lower levels of energy intake.
  5. The maintenance of substantial amounts of milk production at relatively low levels of energy intake cannot be explained just on the basis of an increased utilization of the subcutaneous fat stored during pregnancy. At the mean dietary energy increment of 281 kcal/day observed during lactation in the present study, it can be calculated from figure 2 that only 124 additional kcal/day would be made available from the body weight changes (a loss of 19 9 body fat/day), resulting in a net gain of 405 kcal/day. Yet the mean volume of milk produced, 747 g/day, would contain an average 515 kcal. Conventional estimates of the efficiency of conversion of dietary energy for human milk production have clearly been misleading. The present results show that calculated efficiency factors vary with the level of energy intake. At a dietary increment of 800 kcal/day during lactation, the calculated efficiency of conversion would be the generally accepted value of 80 per cent, but at the mean measured increment of 281 kcal/day, as just calculated, the apparent efficiency is 127 per cent -at first sight a nonsense factor. The anomaly can be resolved, however, if it is accepted that there have been substantial compensatory alterations in the non lactational component of the mother's physiological efficiency.
  6. We have produced circumstantial evidence for energy-conserving adaptations during lactation as well as pregnancy that ensure foetal development and subsequent milk production without the need for excessively high energy intakes or, alternatively, drastic changes in the body composition of the mother. The data presented indicate that, for the type of population studied, current recommended daily amounts of dietary energy during pregnancy and lactation are unnecessarily high: lower mean values of 2,000 kcal and 2,400 kcal, respectively, could be safely adopted. The suggested value for lactation would also enable the mother to attain her pre-pregnancy weight within a more acceptable time.

Acknowledgements

We thank Professor C. Douglas, Mr. R.E. Robinson, and Dr. N.R.C. Roberton and the staff of the Cambridge Maternity Hospital for their collaboration, and Miss M.J. Whichelow for her help in recruiting the subjects. This study was financially supported by the Department of Health and Social Security.