Healthy Lifestyles and Health Promotion: A Challenge and an Opportunity for Nutrition Science

摘要

Diabetes and coronary heart disease (CHD) are rare or unknown in traditional societies (hunter-gatherer, subsistence agriculture). Such societies are characterised by high levels of physical activity, relatively low energy diets, and leanness throughout life. However, when such populations westernise they undergo a very predictable and consistent pattern of lifestyle changes, involving inter alia a move to a more energy dense diet (which is frequently of poor nutritional quality) and an increasingly sedentary lifestyle. This results in steadily increasing population mean body mass index (BMI), and increasing prevalence of obesity over time and increases the prevalence of a range of obesity-related conditions including type 2 diabetes, hypertension and other manifestations of cardiovascular diseases (CVD). Prevalence of the major chronic diseases and conditions such as cardiovascular diseases, type 2 diabetes, obesity and certain cancers exhibit wide variations between countries and within countries over time. In terms of trends over time in CVD mortality, two distinct patterns have emerged. Impressive reductions in a number of affluent western countries such as Finland, the US, Canada and Australia where the epidemic peaked in the 1960's and became the target of intensive primary and secondary prevention interventions (diet, lifestyle and clinical care). In North Karelia (Finland) CVD mortality fell by more than half between the early 1970's and the early 1990's. In Poland mortality from CHD and related conditions rose steadily from 1970 to peak in the late 1980's, and fall quite sharply by the mid 1990's. The reasons for this positive change are not well understood but it was speculated that they may be related to recent improvements in dietary quality. The second pattern of change is a distinct worsening of CVD mortality in a number of less affluent countries as they become more economically developed and adopt a more westernised lifestyle, India, China and certain countries from the former communist block of Eastern Europe fit into this category. The trend with type 2 diabetes (and its major risk factor, obesity) is, unfortunately, only in one direction ― worsening in all countries for which data exists. For example, over the last 20 years as in other developed societies, diabetes prevalence in Australia has doubled in association with greatly increased rates of obesity. Even sharper increases in prevalence have been documented in high-risk populations such as Australian Aborigines. Unless the escalating epidemic of obesity can be stemmed, there seems little chance of attenuating this worrying trend. Understanding the reasons for these different and changing patterns of chronic disease is essential to developing rationally based approaches to health promotion. Coronary heart disease and type 2 diabetes are particularly interesting examples of non-communicable diseases closely linked to diet and other aspects of lifestyle.