Monitoring dietary intakes
Ian Macdonald, ed. 1991. ILSI Monographs, ILSI Europe, Springer-Verlag. 259 pp.
This monograph on dietary survey methodology and applications is one in a series sponsored by the International Life Sciences Institute (ILSI) on the application of scientific advances in nutrition, toxicology and food safety. Scientists in national Institutes and academia have contributed in-depth discussions related to obtaining and using food intake data for various purposes, including risk assessment and national monitoring and surveillance programmes to estimate nutrient intakes and human exposure to food additives, pesticide and veterinary drug residues, packaging materials, heavy metals and radio-caesium.
In regard to methodological issues discussed, nutritionists responsible for interpreting dietary survey data should find the chapter on within-person variability particularly useful for assessing the prevalence of intakes above or below a set cutoff point. Application issues discussed include a summary report of the National Research Council study on risk assessment methods used to estimate pesticide residue levels in the diet, focusing on infant and children, and a summary of the Life Science Research Office report of the Committee on Pesticides in the Diets of Children. The United States Food and Drug Administration pesticide residue monitoring programme is also described with a summary of results based on the Total Diet Study conducted. In the chapter on comparing actual to potential intakes, approaches to estimating intake of food additives are illustrated by a detailed description of the post-market surveillance system and approval process used by Canada for the sweetener aspartame.
As dietary intake studies are generally time consuming and expensive, this monograph meets the continuing need to share expertise in the development and evaluation of methods for estimating dietary intakes. International efforts to coordinate dietary intake studies are discussed, including the Joint UNEP/FAO/WHO Food Contamination Monitoring Programme (GEMS), the Joint FAO/WHO Food Standards Programme and the relevant committees of the Codex Alimentarius Commission. The volume is useful in drawing together research from North America, Europe and Japan. It could have benefited from a review of how these scientific advances are being applied in less developed regions. The topics covered address the need for more accurate interpretation of survey data, emphasized by the growing worldwide concern for food safety and the increasing importance of food legislation in an integrated Europe.
Patricia Behlen Dexter
Nutrition Officer,
Nutrition Planning, Assessment and Evaluation Service,
FAO, Rome
Human energy requirements - a manual for planners and nutritionists
W.P.T. James and E.C. Schofield, FAO. 1990. Oxford, UK. Oxford Medical Publications. 172 pp. Price £45.00. ISBN 0-19-261891-1. Estimating human energy requirements has remained an active research topic throughout the history of nutrition science, reflecting the centrality of energy and food to human life. Obtaining the closest estimate of energy needs and clarifying the factors that affect energy requirements of individuals and groups of people have important policy implications for management and planning. The subject has involved FAO for over 40 years, in conjunction with other UN agencies, resulting in the production of numerous reports from special committees and expert consultations. The most recent was Energy and protein requirements - Report of a Joint FAO/WHO/UNU Expert Consultation, published in 1985 under the WHO Technical Report Series (No. 724). As better techniques and more scientific data become available, estimates of energy needs are refined and based more on actual measurements than on assumptions. Nevertheless, the application of the methodology remains complex. This application aspect has been addressed in the FAO manual Human energy requirements - a manual for planners and nutritionists.
The manual was compiled by W.P.T. James and E.C. Schofield with the cooperation of the Food Policy and Nutrition Division of FAO and other individuals. Definitions and calculations of human energy needs, and the factors that can alter their magnitude, are covered. The manual includes a Lotus 1-2-3 spreadsheet program specifically created during the preparation of the manual that allows a step-by-step calculation of the energy needs of populations or population subgroups, drawing upon either the provided data base or data supplied by the user.
The manual is organized into eight chapters and contains six appendixes. The first chapter gives some overview of energy requirements and allowances. Other chapters deal with the principles of energy balance and energy needs; different levels of analysis in estimating requirements; the impact of urbanization and population structure; energy allowances in different physiological patterns and under various conditions; the effects of different assumptions on estimated allowances; adaptation and survival on low intakes; and special applications of energy requirement calculations.
As the main objective of this much-needed manual has been to overcome the complexity of calculating energy requirements, it is written in a readily understandable manner. Good use is made of numerous diagrams and figures to enhance the clarity of the points made. The manual also contains a glossary in which the scientific terms - as meant and used in the manual - are defined.
The English version of the manual is published by Oxford Medical Publications, Oxford University Press, and can be purchased by writing to: The OUP Bookshop, 116 High Street, Oxford OX1 4BZ, UK. In addition, a Chinese translation has been published by the Chinese Academy of Agriculture, and French and Spanish versions are in preparation for publication in 1992. Information for ordering these last two versions will be given at a later date.
Robert C. Weisell
Nutrition Officer,
Nutrition Planning, Assessment and Evaluation Service, FAO, Rome
Diet and disease in traditional and developing societies
G.A. Harrison and J.C. Waterlow, eds. 1990. Based on 13 papers presented at the 30th Symposium of the Society for the Study of Human Biology. Cambridge, New York and Melbourne, Cambridge University Press. Hardback, 435 pp. ISBN 0-521-38454-0. The mix of the fundamentals of physiology with the fundamentals of social anthropology distinguishes this book from most other books on diet and disease. In the introductory chapter G.A. Harrison says that food is as much a social resource as a collection of nutrients and that it can dominate social organizations as much as biological needs. He concludes that the interdisciplinary approach is of great importance in understanding and solving the problems of human nutrition. However, in the developing countries of the world the multisectoral approach for combating malnutrition has been advocated for a long time, with precious few success stories. Experience shows that in most countries nutrition is firmly installed in the health sector, where it receives financial allocations as a meagre portion of public health programmes and research. Consequently, nutritional understanding and improvement is left largely to a few dedicated professionals and non-governmental organizations with insufficient resources. It therefore seems crucial that nutrition be recognized and promoted as a discipline and a sector in its own right with multidisciplinary professional competence at its disposal.
J.C. Waterlow presents mechanisms of addptation to low energy intakes. He cites low body weight, reduction in the amount or cost of physical activity and increased biochemical efficiency all as plausible strategies to economize energy. Low body weight implies less muscle mass and therefore less absolute working capacity. The author argues that the energy expenditure of a tall person would be more cost effective than that of a short person of similar body mass index (BMI). Physical activity is essential for livelihood, but some discretionary activity is desirable for improving the quality of life. In energy restriction, discretionary activities are left out and adaptation comes from weight loss, cutting out some work, slowing down the rate of work and doing work in the most cost-effective manner. Biochemical efficiency has been postulated from the reduction in basal metabolic rate (BMR) of the adults with low BMI, possibly because of variability in rates of protein turnover, iron-pumping and efficiencies of ATP production and utilization. Waterlow concludes that research leading to better understanding of the proposed mechanisms would elucidate the true costs of adaptation and define the range of acceptable costs for guiding food policy.
G.B. Spurr explains the impact of chronic undernutrition on productivity and the physical work capacity (PWC) in adults and children. The endurance capacity of nutritionally normal children, as measured from maximum oxygen consumption (VO2 max), is significantly and consistently higher than that of as undernourished children. PWC increases as body weight increases with age in both sexes but is higher in boys than in girls. Spurr presents impressive evidence of a direct relationship between nutritional status, lean body mass and PWC. Well-nourished children can sustain an effort for a longer period of time. In adults VO2 max is positively correlated with height and muscle cell mass. PWC and hence productivity of stunted adults with low body weights and less lean body mass are poorer than those of well-nourished adults. An increase in muscle cell mass after supplementary feeding, especially of proteins, improves PWC.
S. Gantham-McGregor emphasizes that morbidity among young children because of infection and nutrient deficiencies hinders their development seriously. She points out paucity of data in this regard.
It is interesting to read a new paper on the aetiology of kwashiorkor, which dominated the scene of nutrition for over 30 years as a protein deficiency syndrome, later on to be accepted as an expression of protein-energy malnutrition alongside marasmus. A.A. Jackson has examined the events and, taking into account recent research evidence, has proposed a complex aetiology of kwashiorkor. He concludes that both extrinsic and intrinsic factors are involved in the disease process. Deranged gastro-intestinal function, resulting in losses of various nutrients and unusual loads of free radicals, has a vital role. The output of glutathione, which defends the body against toxic species, is perturbed when gastro-intestinal integrity is lost.
B. Hetzel records the prevalence, effects and consequences of iodine deficiency during periods of growth and development of children. He also reviews the strategies and methods available for the correction and control of Iodine deficiency diseases (IDDs), such as consumption of iodized salt and administration of Iodized oil by injection or mouth. The substantial progress in the prevention and control of IDDs is seen through actions launched by the International Council for the Control of Iodine Deficiency Disorders (ICCIDD) and a global strategy for a "Ten-Year Programme" adopted by the United Nations agencies.
When discussing the synergism which exists between infection and malnutrition, S.J. Ulijaszek examines the evidence as to how a host's nutritional status will affect how it confronts various pathogens. Different nutrient deficiencies appear to influence Immuno-competence of the groups at risk differently.
H.M. Hodkinson reports on the complex interaction between illness and nutrition in the elderly in the United Kingdom. It is pointed out that energy intake tends to fall with age in the absence of illness, probably in step with falling body weight and more particularly falling lean body mass.
J.D. Haas and J.-P. Habicht analyse growth and growth charts in the assessment of preschool nutritional status. They stress the use of appropriate indicators for specifying types of undernutrition and cut-off values for specific interventions. Where resources are limited they plead for the judicious application of the simpler methods in preference to sophisticated techniques employing modern technology.
The paper of P.S. Nestel is a case-study from the Sudan examining the factors that lead to nutritional vulnerability of children. One in seven children in northern Sudan is classed as thin and one in three is stunted. Nestel advocates measures such as better pricing policy, provision of buffer stocks, developing marketing structures and food aid to combat malnutrition in a country where population growth rate is still 2, 8 percent.
S.S. Strickland's paper on traditional economies and patterns of nutritional disease is an interesting analysis of the contribution of child labour to the health status of siblings, selected buffering of children against seasonal nutritional stress, and the functional consequences of small body size for physical work capacity and productivity. In regard to child labour, it seems to be socio-economic adaptation that in rural Bangladesh male children become net producers by 12 years of age, in contrast to children of individual couples who are net consumers until they become parents themselves. There is a suggestion that vulnerable children tend to be favoured when access to resources is increased. However, the issue of buffering small children needs more research for elucidation. The author concludes that in traditional economies nutritional status on is more likely to affect PWC and productivity in irrigated rice farming than in slash-and-burn subsistence farming. The innumerable factors involved in this relationship need investigation for better understanding.
The paper on social adaptation to seasons and uncertainty in food supply presents the exhaustive work of I, de Garine and S. Koppert in West African communities. The evidence is examined in the light of their observation, "All animals are submitted to seasonal variations in their diet, are adapted to their environment and reach an acceptable level of fitness. Why should it not be the case for Man, especially in traditional societies?" It sounds teleological, but they have presented some nutritional and a lot of anthropological evidence that humans successfully adapt to hungry seasons and uncertain food supplies.
B. Harriss skilfully examines sex bias in food distribution within households in South Asia and discusses its consequences in terms of malnutrition, morbidity and mortality. The analysis of the studies she quotes shows that gender differences in nutrient distribution are not dramatic and that nutrition intake by itself does not seem to be a good indicator of female disadvantage and excess female mortality. Social class relations, gender relations and relations between the generations within the household seem to be more important determinants of mortality and malnutrition of females.
Through his paper on the cultural context of diet, disease and the body, R. Burghart shows his impressive knowledge of the relationship between food, mind and body in the beliefs and practices of many traditional societies and cultures, especially that of Hindus in India and Hindu émigrés in the United Kingdom. Beliefs die hard, particularly in relation to food; nevertheless, contrary to what Burghart has observed, food habits of Indian children, and through them those of the families, have changed considerably as a result of influences and experiences in school and exposure to fast foods. Within India, respect for the cultural connotations of food still exists, but is not necessarily important for a majority of people. History tells us that millions of human beliefs that could not stand the test of time and the wisdom of reasoning have been discarded. Nutrition education is a powerful tool if used intelligently and not mixed with pop nutrition.
In conclusion, the book provides up-to-date knowledge of the subjects presented and highlights the areas where more research is needed. It offers excellent, thought-provoking reading. It will certainly make a valuable addition to personal and institutional libraries.
Rahmat U. Qureshi
Regional Food Policy and Nutrition Officer,
FAO Regional Office for Asia and the Pacific
