Protein-Energy InteractionsProtein-Energy InteractionsOn behalf of the UN ACC-Subcommittee on Nutrition, the International Dietary Energy Consultancy Group (I/D/E/C/G) has been established for the study of dietary energy intake in relation to the health and welfare of individuals and societies by the United Nations University. Its specific objectives are:
1. The compilation and interpretation of research data on functional and other consequences of deficiency, change or excess of dietary energy.
2. The identification of related research needs and priorities, and the promotion of needed research.
3. The publication of scientific and policy statements and other information on the significance of chronic deficiencies and excesses of dietary energy.
4. The identification and promotion of appropriate and practical means of corrective action.
I/D/E/C/G Steering Committee:
- Dr. N.S. Scrimshaw, UNU, Chairman
- Dr. J.G.A.J. Hautvast, IUNS
- Dr. B. Schürch, Executive Secretary
I/D/E/C/G Advisory Group (1991/92)
One-year term:
- Dr. G. Beaton, Toronto, Canada
- Dr. A. Ferro-Luzzi, Rome, Italy
- Dr. G. Pelto, Storrs, USA
Two-year term:
- Dr. W.P.T. James, Aberdeen, Scotland, U.K.
- Dr. E. Pollitt, Davis, USA
- Dr. P.S. Shetty, Bangalore, India
Three-year term:
- Dr. E. Jéquier, Lausanne, Switzerland
- Dr. J.S. Ju, Seoul, Korea
- Dr. R. Uauy, Santiago, Chile
The digitalization of this publication was made possible by a grant from the Nestlé Foundation
Some basic aspects of protein-energy interrelationships
1. Introduction
2. Energy dependency of protein and amino acid metabolism2.1. Qualitative aspects
2.2. Quantitative aspects
2.3. Correlations between energy and protein metabolism
Amino acid oxidation and food intake
1. Introduction
2. Nitrogen balance and amino acid oxidation
3. Amino acid oxidation during periods of positive or negative energy balance
4. Interactions between energy and protein metabolism
5. Amino acid degradation and gluconeogenesis
6. Summary
References
The metabolic basis of amino acid requirements
Abstract
1. Introduction: The nature of the problem
2. Nutrient requirement models
3. The Millward & Rivers requirement model: Qualitative aspects
4. The variable extrinsic component of the maintenance requirement4.1. Indispensable amino acids as toxic metabolites
4.2. Diurnal cycling5. The anabolic drive
6. Hormonal components of the anabolic drive
7. Protein requirements: Formal statement
8. The issue of protein quality8.1. Accretion: Both net and transient
8.2. Minimum obligatory needs: Theoretical predictions9. Stable isotope studies
10. Practical experience of biological values of dietary protein
11. Urea salvage
12. Indispensable amino acid requirements for the anabolic drive
13. Conclusions
References
Commentary on paper by D.J. Millward
Critique of protein-energy interactions in vivo: Urea kinetics
Abstract
1. Introduction
2. General considerations2.1. Functional metabolic demand
2.2. Carbon flux and nitrogen flux
2.3. Functional metabolic mass of protein
2.4. Specific limiting nutrients
2.5. Limitations imposed by protein quality
2.6. Amino acids: Essential, non-essential and conditionally essential3.1. Present perception of nitrogen disposal
3.2. Urea production
3.3. Urea excretion
3.4. Salvaged urea nitrogen
3.5. The 'effective dietary intake' of nitrogen
3.6. Limits of adaptation to low-protein diets
3.7. Implications of salvaged urea nitrogen
Abstract
1. Introduction
2. The effects of different levels of energy intake on protein metabolism3. The effects of different levels of protein intake on energy metabolism
4. Protein/energy ratios
5. Summary and conclusions
References
Abstract
1. Introduction
2. Influence of nutrient intake on nutrient oxidation
3. Effect of energy intake on nitrogen retention3.1. Fasting and very low caloric intake
3.2. Moderately hypocaloric diets
3.3. Maintenance diets
3.4. Energy intake in excess of maintenance4. Effect of protein intake on nitrogen retention
4.1. Normal and obese subjects
4.2. Severely depleted subjects
4.3. Moderately depleted subjects5. The role of glucose and lipid in nitrogen sparing
5.1. Healthy young subjects
5.2. Patients receiving total parenteral nutrition6. Mechanisms of the sparing effect of dietary carbohydrate and fat
7. Effect of amino acid plasma levels on protein synthesis
8. Practical considerations: Role of the thermic effect of nutrients
9. Conclusions
References
1. Respiratory quotients in semi-starvation
2. Respiratory quotients in experimental semi-starvation
3. Respiratory quotients and substrate oxidation rates in chronically energy deficient subjects
4. Substrate oxidation rates during dietary thermogenesis in chronic energy deficiency
5. Effects of refeeding or supplementation on respiratory quotients and substrate oxidation rates of CED subjects
Acknowledgements
References
Effects of protein-energy interactions on growth
Abstract
1. Introduction
2. Mechanisms for effects of protein and energy on growth2.1. Insulin and insulin-like growth factors
2.2. Growth hormone
2.3. Epidermal growth factor
2.4. Corticosteroids3. The determinants of catch-up growth
4. Effect of the protein/energy ratio on growth of premature infants
5. Effect of protein and energy on growth of children with primary malnutrition
6. Effect of the P/E ratio on growth of children with malnutrition secondary to chronic renal insufficiency
7. Conclusions and speculations
Acknowledgements
References
Protein-energy interrelationships during rapid growth
1. Efficiency of protein deposition
2. Protein turnover during rapid growth
3. Energy cost of protein synthesis
References
Quantitative relationships between protein and energy metabolism: Influence of body composition
Abstract
1. Introduction
2. Theoretical basis
3. Constancy of tissue mobilisation
4. Tissue mobilisation in the obese
5. Allometric analysis
6. Conclusions
References
Protein-energy relationships in pregnancy and lactation
Abstract
1. Influence of gestational weight gain on pregnancy outcomes
2. Protein needs during pregnancy2.1. Influence of gestational weight gain on protein needs
2.2. Efficiency of protein utilization during pregnancy
2.3. Influence of dietary energy on protein utilization
2.4. Summary of protein requirements during pregnancy3. Energy requirements during pregnancy
3.1. Influence of gestational weight gains on energy needs
3.2. Physical activity and pregnancy
3.3. Summary of energy requirements during pregnancy4. Protein needs during lactation
4.1. Estimation of protein needs
4.2. Influence of protein intake on milk composition
4.3. Studies of whole-body protein turnover
4.4. Effects of protein intake on milk production§
4.5. Summary of protein needs during lactation§5. Energy needs during lactation
Abstract
1. Energy metabolism in exercise
2. Are protein requirements affected by exercise when energy requirements are met?
3. Muscle protein breakdown and amino acid oxidation
4. Substrate metabolism in exercise
5. Effect of exercise on protein synthesis
6. Summary and dietary recommendations
Acknowledgements
References
Influence of physical activity on energy and protein metabolism
1. Exercise and efficiency of dietary energy and protein utilization
2. Effects of reduced physical activity on energy and protein metabolism
3. Energy substrates and changes in exercise pattern
References
Exercise, aging and protein metabolism
1. Body composition changes with age and their consequences
2. Fuels used to meet various components of energy requirements
3. Age and dietary protein needs
4. Exercise-induced muscle damage and acute phase response
5. Exercise and protein metabolism
6. Summary
References
Abstract
1. Introduction
2. Early total starvation2.1. Energy metabolism
2.2. Protein metabolism
2.3. Protein/energy ratios3.1. Body fat
3.2. Implications of initial body weight and fat stores on protein-energy interrelationships
3.3. Evidence for the first postulate of the model: Survival time in relation to body composition
3.4. Evidence for second postulate of the model: During prolonged starvation the contribution of protein oxidation to energy expenditure is less in obese than lean subjects
3.5. Starvation in man and other species4.1. Duration of dieting
4.2. Protein and energy intake
4.3. Body composition
4.4. Exercise5. Some other issues, conclusions and recommendations
References
Impact of gastrointestinal function on protein-energy interactions and nutritional needs
Abstract
1. Gastrointestinal function in protein-energy malnutrition
2. Diarrheal diseases
3. Nutritional recommendations
References
Role of the gastrointestinal tract in energy and protein metabolism
1. Introduction
2. Cell and protein turnover
3. Nutrient absorption
4. Protein synthesis
5. Restriction of energy and protein intake
6. Fat absorption and exocytosis
7. Chronic environmental enteropathy
References
Effect of protein-energy interaction with reference to immune function and response to disease
Abstract
1. Introduction
2. Outlining the issues
3. Host metabolism and host defense
4. The metabolic profile of the infected host
5. The role of cytokines
6. Cytokine regulation: Natural antagonists and biological modulators
7. The future
References
Nutrition of immune cells: The implications for whole body metabolism
2.1. Near-equilibrium and non-equilibrium reactions
2.2. The flux-generating reaction3. Use of maximum activities of enzymes as quantitative indices of maximum flux through metabolic pathways
4. Enzyme activities as indication of the capacity of major energy providing pathways in immune cells
5. Glutamine and the immune cells
6. Glutamine - A link between muscle and the immune system6.1. Glutamine synthesis in skeletal muscle
6.2. The transport of glutamine across the muscle membrane: Glutamine uptake and release7. Large decreases in the concentration of glutamine in plasma
8. The clinical significance of the role of glutamine in immune cells
9. The effects of glutamine provision for the patient
10. Branched-point sensitivity, substrate cycles and thermogenesis
References
Abstract
1. Introduction
2. History 1900-1960
3. Indirect calorimetry and N balance in surgical patients
4. Nitrogen balance: The role of energy balance and N intake4.1. Normal subjects
4.2. Depleted patients
4.3. Injured patients
Protein and energy requirements following burn injury
Abstract
1. Introduction
2. Resting energy expenditure2.1. Mechanism of hypermetabolism
2.2. Prediction of resting energy expenditure in burned patients3. Relationship of total energy expenditure (TEE) to REE
4. Sources of energy
5. Protein requirements
Acknowledgements
References
Protein-energy relationships: Experience with parenteral nutrition
Abstract
1. Introduction
2. Metabolic response to starvation
3. Metabolic response to stress
References
Modifications of parenteral nutrition support for critical surgical illness
Dietary protein/energy ratios for various ages and physiological states
1. Definition, interpretation and uses
2. Calculation of recommended P/E ratios
3. Recommended P/E ratios
4. Food sources of energy and proteins
References
Effects of disease on desirable protein/energy ratios
1. Effects of infections on nutritional status
1.1. Anorexia
1.2. Cultural and therapeutic practices
1.3. Malabsorption
1.4. Catabolic losses
1.5. Anabolic losses
1.6. Fever
1.7. Additional intestinal losses2. Environmental ('tropical') enteritis
3. Other chronic infections
4. Energy vs protein requirements
5. Possible role of specific amino acids
Amino acid scoring in health and disease
1. Introduction
2. Amino acid scoring in health2.1. Protein quality evaluation: The protein digestibility-corrected amino acid score method
2.2. Protein digestibility
2.3. Amino acid scoring patterns3. Amino acid scoring in special cases and disease
3.1. Amino acid essentiality
3.2. Glycine
3.3. Glutamine
3.4. Arginine
3.5. Cysteine/taurine
3.6. Branched-chain amino acids (BCAAs)
1. Energy expenditure and metabolism
1.1. Energy expenditure of free-living populations
1.2. More measurements of activity patterns in free-living populations
1.3. Effects of carbohydrates in the diet on fat deposition2. Protein metabolism and requirements
2.1. Amino acid oxidation
2.2. Amino acid requirements
2.3. Protein requirements during pregnancy and lactation
2.4. Control of urea recycling from the gut
2.5. Limits to the de novo synthesis of 'conditionally essential' amino acids
2.6. Special roles of particular amino acids3.1. Methods of measurement
3.2. Composition of lean body mass
3.3. Composition of weight gain during pregnancy4.1. Variability of weight gain and its effect on protein requirements
4.2. Factors limiting protein deposition
4.3. Effects of frequent versus intermittent feeding on growth
4.4. Quantitative and qualitative requirements for catch-up growth5.1. Potential causes of stunting
5.2. Reversibility of stunting6.1. Effects of physical activity on metabolism and body composition
6.2. Energy intake and physical activity
6.3. Changes in life-style7.1. Interactions between energy, protein and amino acid intakes and cytokine responses
7.2. Methods of quantifying losses imposed by infection
7.3. Development of field methods for assessing the severity and intensity of infection
7.4. Interaction of protein-energy status, immunizations and immune status8. Functional consequences
9. Variation
List of participants