Activities and publications 1987-1995
Chronic energy deficiency: Consequences and related issues
A workshop was held at INCAP in Guatemala in August of 1987 to discuss effects of chronic energy deficiency on behavioral development, stature, work capacity and productivity. Papers were also presented on the socioeconomic consequences of and responses to food deprivation, seasonality in energy metabolism, the effect of energy supplementation, research on metabolic adaptation to low energy intake, and maternal energy requirements. The proceedings of the meeting were published as the first volume in the IDECG Series entitled "Chronic energy deficiency: consequences and related issues" which is available from the IDECG secretariat free of charge.
Definition of chronic energy deficiency in adults
IDECG appointed a working group to propose an operational definition of chronic energy deficiency in adults. The recommendations of this group appeared as a discussion paper entitled "Definition of chronic energy deficiency in adults" in the European Journal of Clinical Nutrition (Vol. 42, 969-981, 1988). They proposed the use of low body mass index (BMI) and energy turnover as indicators of chronic energy deficiency in adults. A follow-up paper, published in the same journal in 1992 (Vol. 46, 173-186), recommended to use BMI alone. Single copies of these articles are available from the IDECG secretariat free of charge.
Standardization of the doubly-labelled water method
In the fall of 1988, IDECG convened a workshop to standardize the doubly-labelled water method for assessing total energy expenditure in humans over time periods from one to three weeks. A 3OO-page consensus report entitled "The doubly-labelled water method for measuring energy expenditure" was published in 199O. Scientists using or planning to use the doubly-labelled water method can obtain a copy of the report from NAHRES, International Atomic Energy Agency, P.O. Box 1OO, A-1400 Vienna, Austria.
Activity, energy expenditure and energy requirements of infants and children
A workshop re-examining the energy requirements of infants and children from the point of view of physical activity and energy expenditure was held in Cambridge, Massachusetts, in the fall of 1989. The workshop proceedings, entitled "Activity, energy expenditure and energy requirements of infants and children", were published as the second volume in the IDECG Series in 199O and are available from the IDECG secretariat free of charge.
Improved protein-energy intakes in early childhood and human capital formation
In the summer of 199O, IDECG sponsored a workshop in Bellagio, Italy, bringing together scientists involved in the follow-up of a longitudinal food supplementation study in Guatemala. Data presented at the meeting indicate that nutritional improvements during the critical period of gestation and the first 2 to 3 years of life can enhance human capital formation assessed by a wide range of variables in adolescence.
A first series of papers presented and discussed at the meeting and dealing with the background of the INCAP longitudinal study, the supplementation effects in early childhood, the demographic and social changes between the two studies, as well as the design and main findings of the follow-up, appeared in the Food and Nutrition Bulletin, Vol. 14, No. 3, September 1992. The IDECG secretariat unfortunately has no more extra copies of this publication.
A second report, entitled "Early supplementary feeding and cognition: effects over two decades" and dealing with supplementation effects on cognition, appeared as a Monograph of the Society for Research in Child Development (Vol. 58, No. 7, 1993, Serial No.135) in the fall of 1993. Interested scientists can obtain single free copies of this publication from the IDECG secretariat.
A third series of papers, focusing on the follow-up study and presenting its results in detail, appeared as a supplement to the April 1995 issue of The Journal of Nutrition. Single copies of this publication are available free of charge from the IDECG secretariat.
In October 1991, IDECG convened a workshop in Waterville Valley, New Hampshire, USA, to explore in depth the full range of dietary, physiological and pathological factors influencing the relative demand of the human body for dietary protein, amino acids and energy. The workshop proceedings, entitled "Proteinenergy interactions", appeared in 1992 as the third volume in the IDECG Series and are available from the IDECG secretariat free of charge.
Functional significance of low body mass index (BMI)
The working group appointed in 1988 to propose an operational definition of chronic energy deficiency in adults, suggested the use of low BMI as an indicator. This recommendation was based to a large extent on theoretical considerations, since empirical data that would have helped to validate the proposed criteria and cut-off points were very scarce at that time. It had, however, a catalytic effect, and a considerable amount of BMI data were collected and analyzed subsequently. From November 4 to 6, 1992, IDECG and FAO convened a meeting in Rome to review in greater depth the functional correlates of low BMI and to try to derive from this a clearer view of the meaning and functional significance of this indicator. The proceedings of this meeting appeared in November 1994 as Supplement 3 to Volume 48 of the European Journal of Clinical Nutrition. Single copies are available free of charge from the IDECG secretariat.
Causes and mechanisms of linear growth retardation (stunting)
A workshop on this topic was held in London from January 15 to 18, 1993. The meeting brought together scientists who had made observations on causes, correlates and patterns of linear growth retardation, with experts on the cellular biology and hormonal regulation of bone growth who could speculate on the mechanisms involved. The workshop proceedings appeared as Supplement 1 to the European Journal of Clinical Nutrition in February 1994. They contain a set of guidelines for scientists interested in further study of mechanisms involved in the prevention or reversal of linear growth retardation in developing countries. Free copies are available from the IDECG secretariat.
Effects of protein-energy malnutrition on behavioral development
In December 1993, an IDECG working group met at the University of California, Davis, to assess current knowledge of the relationship between undernutrition and behavioral development in children and to interpret it in the context of current theory. The papers prepared by working group members to serve as a basis of discussion during the meeting were reviewed and revised and appeared as Supplement 8 to the August 1995 issue of The Journal of Nutrition. Free copies are available from the IDECG secretariat.
A much shorter consensus report of the group has been widely circulated and reviewed. It will be published in 1997 as a Social Policy Report of the Society for Research in Child Development.
Energy and protein requirements
A series of papers on human energy and protein requirements were commissioned and discussed at a workshop in the fall of 1994 at the London School of Hygiene and Tropical Medicine. Newer estimates of energy requirements (based on data of energy expenditure), are lower than earlier ones (based on energy intakes) in infants and children under 8 years of age, but higher in children over 12 years of age (particularly in rural areas of developing countries). In estimates of energy requirements of pregnant women, energy savings due to a reduction of physical activity should not be taken for granted, but only be included in calculations where they actually occur. The same reasoning should be applied to allowances made for post-partum weight loss in lactating women. In older individuals, energy requirements are very variable and tend to be more activity- than age-related. New estimates of the protein intake of breast-fed infants are lower than earlier ones. There is still some controversy about amino acid requirements of children and adults because the existing data base is fraught with methodological problems. The group accepted ad interim the recommendations of the 1991 FAO/WHO Expert Consultation. New studies undertaken since should soon provide information that will reduce current uncertainties in this area. The workshop proceedings appeared as a supplement to the February 1996 issue of the European Journal of Clinical Nutrition; free copies are available from the IDECG secretariat.
Activities in 1996 and work in progress
Management of severe malnutrition
IDECG appointed a small working group to review the report published by WHO on this topic in 1981, as well as other relevant publications, and to develop an updated manual for senior health workers involved in the treatment and management of children suffering from severe malnutrition. A first draft, to which most working group members contributed, was edited by B. Torun in 1992. Subsequent versions were prepared in close collaboration with WHO and under the editorial leadership of M. Golden. The objective of the manual is to promote the use of the best available therapy in order to reduce the number of deaths from severe malnutrition, to shorten the duration of hospital stay, and to provide the basis for nutritional rehabilitation. The main emphasis is on the treatment and management of severely malnourished children; the treatment of malnourished adults is briefly discussed in one section. The manual is in press as an IDECG WHO publication.
Re-analysis of basal metabolic rate (BMR) data of humans
Estimates of energy requirements are generally based on estimates of energy expenditure. Under most circumstances, the BMR is the most important component of energy expenditure, and allowances made to cover additional expenses, mostly for physical activity, are most conveniently expressed as multiples of BMR. It is therefore of great importance to have valid BMR data and equations allowing to predict BMR from other, simpler parameters.
A large number of new BMR data have been obtained since Schofield, Schofield & James published their analysis and predictive equations in Human Nutrition: Clinical Nutrition in 1985. A considerable amount of BMRs have also been collected in population groups that were underrepresented in the data pool up to that time. IDECG therefore commissioned a re-analysis of BMR data under the supervision of C.J.K. Henry at Oxford Brookes University and J.V.G.A. Durnin at the University of Glasgow. The new analysis included a larger number of more rigorously selected data, grouped in age bands which are more representative of the physiological and biological changes that occur with age. More emphasis was placed on ethnic grouping and, when BMRs were adjusted for weight, differences were found between Caucasians and adults from some other ethnic backgrounds. Data unfortunately did not allow evaluation of differences in body composition - the most plausible explanation for the observed differences in BMR. Predictive equations derived from this new analysis differ from previous ones for males O-3, 30-60 and 60+ years of age. It is planned to publish this report, together with the analysis of the energy cost of physical activity, as a supplement to a scientific journal.
Energy cost of physical activity
To estimate energy requirements expressed as BMR multiplied by a factor which reflects primarily energy expenditure for physical activity, it is necessary to have adequate data on the energy cost of a wide variety of physical activities. Such data, obtained by indirect calorimetry, exist, but there is no recent, systematic and comprehensive compilation of this information. A research assistant at the London School of Hygiene and Tropical Medicine under the direction of P.S. Shetty and J.V.G.A. Durnin is re-analyzing this information and preparing it for publication.
A comprehensive review of the literature from 1966 to 1995 has been completed. over 450 references have been identified, most of them with abstracts. Where abstracts did not exist they were written. A large portion of the good data that are available were published before 1966 and summarized in the Durnin/Passmore book on "Energy, work and leisure"; they will also be included. The complete bibliography, organized by type of activity, will be published as an internal document by the Department of Public Health Policy of the London School of Hygiene and Tropical Medicine.
More than 60 publications meet pre-established screening criteria and report energy costs of specific activities. These will be standardized and reported in the form of tables. An annotated bibliography of this subset of papers and the tables of energy costs of various physical activities will be published as a supplement to a scientific journal, if possible together with the re-analysis of BMR data.
Based on the tables, a software package for the analysis of time and motion studies has been developed by LSHTM staff and is being tested. It is hoped that IDECG will be able to distribute it together with the publication.
Urea nitrogen salvage and bacterial synthesis of amino acids in the gut
The IDECG workshop on protein-energy interactions showed that there are still major gaps in our understanding of the metabolic basis of protein and indispensable amino acid (IAA) requirements of the human organism in general and of the young child in particular. Urea nitrogen can be salvaged in the large bowel, but the conditions under which this salvaging occurs and the extent to which bacteria might be able to synthesize IAA in the gut still remain unclear. This complicates a meaningful examination of amino acid and protein requirements. The panel discussing research needs and priorities felt, therefore, that the clarification of this issue should be given a high priority.
T. Forrester at the Tropical Metabolism Research Unit in Kingston, Jamaica, J. Millward at the University of Surrey and A.A. Jackson at the University of Southampton investigated these issues, using j15N15N]urea to assess the extent to which nitrogen from hydrolysed urea might be incorporated into Iysine, alanine, glycine and histidine by measuring the 15N enrichment in these amino acids isolated from urine. The results, that will soon be published in detail, provide support for the proposition that urea metabolism in the colon can represent a nutritionally significant process altering the pattern of amino acid supply to the host.
Determination of the adult requirement for lysine
The 1994 IDECG workshop on energy and protein requirements reviewed the recommendation of the 1991 FAO/WHO report suggesting that the requirements for the essential amino acids in adults were two to three times higher than assumed for the preceding 30 years. This conclusion was based on new MIT studies using stable isotope methodology to establish requirements for leucine, valine, threonine and methionine. The vast majority of IDECG workshop participants accepted this conclusion but regretted that there were no direct studies using this methodology to determine the requirement for Iysine, the amino acid most likely to be limiting in the predominately cereal-based diets of the poor in developing countries. Therefore, it assigned a high priority to extending stable isotope studies to Iysine.
UNU, on behalf of IDECG, obtained a grant for this purpose from the Global Cereal Fortification Initiative jointly sponsored by Ajinmoto Inc. and Kyowa Hakko Kogyo Co. Ltd. The studies are being conducted under the supervision of A.V. Kurpad at the Dept. of Physiology of St. John's Medical College in Bangalore, India, and V.R. Young at the Massachusetts Institute of Technology (MIT) in Cambridge, USA.
The technique involves feeding graded levels of Iysine to determine the intake that just equals the rate of Iysine oxidation. The requirement level is then crosschecked by measuring the level of Iysine at which leucine is oxidized, because Iysine deficiency prevents it from being used for protein synthesis. The studies began in mid-1995, and final results are expected in
1997. Preliminary results are consistent with the values extrapolated from similar studies with leucine and threonine.
Meta-analysis of nitrogen balance studies
Another activity recommended at the IDECG workshop on energy and protein requirements in London is a meta-analysis of nitrogen balance studies to validate protein and amino acid requirements. P. Pellett at the University of Massachusetts, with the assistance of N.S. Scrimshaw and V.R. Young, has identified more than 50 studies since 1951, including more than 3,000 N balance periods incorporating about 30,000 N balance days. The analysis is progressing well and preliminary results suggest that the level of about 0.8 9 protein/kg/d recommended by FAO/WHO/UNU in 1985 is appropriate. After this meta-analysis has been completed, there will probably be no need for additional conventional N balance studies in adults.
The causes and consequences of intrauterine growth retardation
A workshop dealing with this topic was held in November 1996. Data presented at the meeting confirm that the prevalence of intrauterine growth retardation ~IUGR) in most developing countries is a major public health problem. The causes of IUGR are multiple and interactive, and their relative importance varies with time, place and population. In developing countries, the major determinants of IUGR are nutritional (as reflected by low gestational weight gain, low pre-pregnancy BMI and short maternal stature), whereas in industrialized countries cigarette smoking is by far the most important etiologic determinant, followed by low gestational weight gain and low pre-pregnancy BMI.
IUGR is associated with impaired immunocompetence, increased morbidity and mortality in infancy and growth deficits persisting into adulthood. Neurological, cognitive and behavioral deficits appear to be most marked from the pre-school years through adolescence. Several epidemiologic studies have shown associations between low birth weight and earlier and higher prevalence of hypertension, coronary heart disease, adult onset diabetes, chronic respiratory disease, autoimmune thyroid disease and some forms of cancer. A systematic review of 124 available randomized controlled trials testing the efficacy of 36 kinds of prenatal interventions, provide strong evidence of benefit only for three of them: protein/energy supplementation, strategies to reduce maternal smoking and antimalarial prophylaxis. The proceedings of this workshop will be published as a supplement to a scientific journal.
Other items on the IDECG agenda
Interactions between nutrition and infection
Research in this area is still hampered by the lack of methods that could be used for the detection of subclinical and low-grade infection. Even once an infection has been diagnosed it is difficult to quantify the stress imposed by it on the organism. It would be desirable to identify indicators of infectious stress with predictive value for supplementary energy and nutrient requirements.
There is also evidence that amino acid requirements may be altered by infection and possibly that additional quantities of some amino acids will improve immune status. These issues can now be explored in human subjects through the use of stable isotopes. IDECG is cooperating with the Section of Nutritional and Health-Related Environmental Studies of the IAEA that is organizing coordinated multi-country research to explore these and related issues.
In infection, decreased intake due to anorexia or therapeutic efforts, decreased absorption and increased catabolic losses concurrently affect nutritional status. Although these processes can be readily demonstrated qualitatively, there is only very limited quantitative information of their relative effect in different infections. Stable isotope procedures will make it possible to measure the oxidation of some key amino acids, even when the infections inducing acute phase and catabolic responses remain subclinical.
Re-examination of chronic energy deficiency and low BMI in adults
The definition of chronic energy deficiency in adults has been one of IDECG's main concerns. Low BMI, recommended as an indicator, has become so closely identified with chronic energy deficiency that adults with a low BMI are now sometimes fed rations that meet their energy needs, but not their needs for other nutrients. In some populations, on the Indian subcontinent for instance, the current definition includes among the chronically malnourished, individuals with an ad libitum access to food, who probably do not belong to that category. IDECG is planning to form another working group to address these and related issues.
IDECG Advisory Group (1995/96)
- Dr. E. Jéquier, Lausanne, Switzerland
- Dr. Jin Soon Ju, Seoul, Korea
- Dr. R. Uauy, Santiago, Chile
- Dr. L. Allen, Davis, USA
- Dr. A. Ferro-Luzzi, Rome, Italy
- Dr. R. Martorell, Atlanta, USA
- Dr. N. Butte, Houston, USA
- Dr. P.S. Shetty, London, UK
- Dr. B. Torun, Guatemala City, Guatemala
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