Introduction

Earlier recommendations for population nutrient intake goals to prevent diet-related chronic diseases were formulated in 1989 by the WHO Study Group on Diet, Nutrition and Prevention of Noncommunicable Diseases. Since then, the very rapid development in related scientific fields and available population-based epidemiological evidence underscored the important role that diet and lifestyle plays, in developing* and developed countries alike, in preventing and controlling increasingly significant causes of disability and premature death due to noncommunicable diseases. In addition, the identification of specific dietary components that increase the probability of occurrence of these diseases in individuals is being further clarified and new reports and proposed guidelines are being developed and published by various governmental bodies and professional organizations, creating much debate and discussion. Moreover, rapid changes in diets and lifestyles resulting from industrialization, urbanization, economic development and market globalization, have accelerated during the last decade and are having a significant impact on the health and nutritional status of populations, particularly in developing countries and those undergoing rapid socioeconomic transition. While standards of living have improved and the access to services has increased, there have also been significant negative consequences in terms of inappropriate dietary patterns and decreased physical activity and a corresponding increase in diet-related chronic diseases, especially among the poor. Food and food products have become commodities produced and traded in a market that has expanded from an essentially local base to an increasingly global one. Changes in the world food systems have contributed to shifting dietary patterns, for example, increased consumption of an energy-dense diet high in fat, particularly saturated fat, and low in complex carbohydrates. This is combined with a decline in energy expenditure that is associated with a sedentary lifestyle—motorized transport and labour-saving devices in the home and the occupational environment, largely replacing physically demanding manual tasks at work and leisure time often being dominated by physically undemanding pastimes. Because of these changes in dietary and lifestyle patterns in both developing and newly developed countries, chronic noncommunicable diseases—obesity, diabetes mellitus, cardiovascular disease, hypertension and stroke and various forms of cancer—are increasingly significant causes of disability and premature death that place additional burdens on already overtaxed national health budgets. Updated scientific evidence and policy recommendations were urgently needed to assist in developing effective national prevention and management strategies for addressing the increasing public health challenge related to diet and health. Thus, the Joint WHO/FAO Expert Consultation on diet, nutrition and the prevention of chronic diseases (Geneva, 28 January–1 February 2002) was organized as part of the normative work of the World Health Organization (WHO) and Food and Agriculture Organization of the United Nations (FAO), which regularly develop and periodically update nutrient requirements and related global guidelines. The Joint WHO/FAO Expert Consultation was one of three Expert Consultations that FAO and WHO had agreed to hold jointly during the year 2001–2002. The other two concerned energy (Rome, October 2001) and protein and amino acid requirements (Geneva, April 2002). Earlier versions of the papers presented in this supplement – except the last one by Nishida et al. on the process, product and policy implications of the Expert Consultation – were prepared as the background papers for the joint WHO/FAO Expert Consultation on diet, nutrition and the prevention of chronic diseases and were peer reviewed. These papers were prepared following a general framework which includes current epidemiological trends of the concerned diseases; review of scientific evidence linking diet and the concerned diseases; strength and weakness of evidence; and policy implications, where possible. After the Expert Consultation, these papers were further developed, revised and finalized by the respective authors incorporating peer reviewers’ comments as well as the discussions of the Expert Consultation in order to be published for wider dissemination of the evidence base for the report of the Expert Consultation. The first paper by Darnton-Hill et al. reviews the continuity of the life course processes and environmental and societal influences that contribute to the development of chronic diseases. There is increasing evidence that chronic disease risks begin in fetal life and continue into old age. Darnton-Hill et al. divide the life course into five stages: fetal development and the maternal environment; infancy and childhood; adolescence; adulthood; and ageing and older people. Although distinct in themselves, each stage merges imperceptibly from one stage to the next with different influences providing the cumulative