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Activities and publications 1987-1996
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 socio-economic 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.
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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.
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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 300-page consensus report entitled The doubly-labelled water method for measuring energy expenditure was published in 1990. 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-14OO Vienna, Austria.
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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.
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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.
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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 Protein-energy interactions, appeared in 1992 as the third volume in the IDECG Series and are available from the IDECG secretariat free of charge.
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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. This volume is out of print and no longer available from the IDECG secretariat.
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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.
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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, revised and appeared as Supplement 8 to the August 1995 issue of The Journal of Nutrition. A much shorter consensus report of the group appeared in 1996 as a Social Policy Report of the Society for Research in Child Development. Free copies are available from the IDECG secretariat.
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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.
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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 appeared as a supplement to the January 1998 issue of the European Journal of Clinical Nutrition; free copies are available from the IDECG secretariat.
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Activities in 1997 and work in progress
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.
Scientists interested in diets made from foods that are available locally in different parts of the world and have been used with some success in the rehabilitation of undernourished patients have started exchanging information on that topic on the Internet site .
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Estimates of energy requirements are now 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 are most conveniently expressed as multiples of BMR. It is therefore of great importance to have valid BMR data and equations enabling predictions of 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 number of BMRs have also been collected in population groups that were under-represented in the data pool up to that time. The Advisory Group of IDECG therefore concluded that a re-analysis of BMR data, meeting very stringent criteria, would be desirable, and the Nestle Foundation agreed to fund this endeavor undertaken under the supervision of Profs. CJK Henry at oxford Brookes University and JVGA Durnin at the University of Glasgow.
Reeves, Henry and Durnin produced a first draft of a bibliographic review of BMR sources. The new database and a preliminary analysis were presented and discussed in December 1997 at an IDECG meeting in Rome. Compared to the previous Schofield, Schofield & James analysis published in 1985, the new oxford analysis includes a larger number of more rigorously selected data, grouped in age ranges 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 of the other ethnic backgrounds; data unfortunately did not allow clarification as to whether this was due to differences in body composition - the most plausible explanation for the observed differences.
The regression lines resulting from the oxford Brookes analysis tend to be generally lower than the Schofield et al. regression lines except for males above 6O years of age. The differences are most marked in the heavier females from 1O to 3O years and inmates from 1O to 6O years. In terms of energy requirements, the differences between Schofield and oxford equations amount to about 13O kcal for a young male adult weighing 5O kg and with a PAL of 2XBMR; in males over 6O, energy requirement estimates would be about 7O kcal higher if one used the oxford Brookes equations.
The variability within the oxford data tends to be larger than that in the Schofield data. The introduction of additional criteria was suggested to explore if they might result in statistically and biologically significant differences and/or a significant reduction of the variance in the data set. More recent data from Africa, India and China tend to be different from older ones and more in line with data of Caucasians. This would be indicative of secular changes, most likely as a result of changes in body composition. It therefore seems desirable to see if limiting the analysis to data collected more recently would make a significant difference. There are several reasons supporting the argument that data obtained by pure oxygen systems (e.g. using the Benedict-Roth spirometer) might be subject to a methodological bias (due to the fact that breathing pure oxygen could affect the normal respiratory pattern) and should be excluded in order to see what effect that would have on the results. It was also proposed to only include data from laboratories with a long-term interest in and practice of collecting BMR data, as reflected by the fact that they published more than one BMR data set and to note the effect that would have on the results.
The Nestlé Foundation is funding a research assistant who will do such additional analyses under the supervision of Prof. Henry. The plan is to publish the results, together with the analysis of the energy cost of physical activity, as a supplement to a scientific journal.
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As mentioned previously, estimates of energy requirements are generally based on estimates of energy expenditure and expressed as multiples of BMR. The method that has probably been used most frequently to determine the factor by which to multiply BMR consists of a combination of a timed activity record and the energy expenditures associated with the most important observed activities. Data on the energy cost of various activities, obtained by indirect calorimetry, do exist, but there is no recent, systematic and comprehensive compilation of this information. The aim of this project is to collect such data from all available sources and to analyze and publish them, together with an annotated bibliography of the documents from which they originated. This work is carried out by postgraduate fellows at the London School of Hygiene and Tropical Medicine, under the supervision of Profs. PS Shetty and JVGA Durnin.
An annotated Bibliography of Studies of the Energy Cost of Physical Activity in Humans, covering the time period from 1966 to 1995 and including over 45O annotated references appeared as a PHP publication of the London School of Hygiene & Tropical Medicine. Copies are available free of charge through the IDECG Secretariat. More than 6O of the publications included in this bibliography 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 the 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 reanalysis 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.
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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 3O 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 lysine.
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 lysine to determine the intake that just equals the rate of lysine oxidation. The requirement level is then crosschecked by measuring the level of lysine at which leucine is oxidized, because lysine deficiency prevents it from being used for protein synthesis. Preliminary results suggest that the FAO/WHO/UNU (1985) requirement levels for adult lysine intake are too low.
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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 5O studies since 1951, including more than 3,OOO N balance periods incorporating about 3O,OOO 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. A preliminary version of this report is anticipated in 1998.
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The energy requirements of humans vary depending upon their physiological state and level of physical activity, modulated further by pathological factors. The metabolic capacity exists for adapting to a wide range of combinations of carbohydrate, fat and protein as energy sources, but the determinants of energy requirements affect the metabolism of the three kinds of macronutrients differently. This, in turn determines the dietary level and combinations of energy-yielding substrates that are appropriate for meeting the quantitative needs for maintenance of body energy balance and functions.
In December 1997, IDECG convened a workshop at FAO in Rome to define quantitatively the upper and lower limits to carbohydrate, fat and protein intake in infants, children and adults under various environmental, physiological and pathological circumstances. The underlying biochemical and metabolic processes involved and their significance were reviewed for their practical dietary implications. This will guide the recommendations that IDECG develops for lower and upper levels of carbohydrate, fat and protein to meet energy needs in the diets of young and adult populations under varying circumstances in both industrialized and developing countries. The proceedings of the workshop are being prepared for publication as a supplement to a scientific journal.
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Other items on the IDECG agenda
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. These and related issues continue to be discussed among a number of the scientists of the IDECG network.
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The participants in an IDECG Advisory Group meeting in Rome recommended to deal with this topic at the next IDECG workshop. The elderly population is very heterogeneous in relation to energy metabolic parameters and the relationship among them is only poorly understood. The BMR data base on the elderly is not very large (about 4OO data points) and probably not very representative. TEE data obtained with the doubly-labeled water (DLW~ method are surprisingly high, suggesting that most of these measurements were made in healthy and unusually active individuals. BMR could, however, be higher per unit lean body mass in older than in younger adults because muscle mass has the tendency to get reduced with age more than organ mass. The lifestyle of the elderly is no longer so strongly determined by work requirements, which means that one might be able to be more prescriptive as far as dietary intakes and particularly physical activity are concerned. Apparently surprisingly small increases in physical activity and/or small weight losses can have considerable metabolic effects (e.g. lowering the incidences of glucose intolerance and diabetes); larger weight losses seem to have a marked effect on the incidence of morbidity and mortality.
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