URBANIZATION AND THE NUTRITION TRANSITION

BARRY M. POPKIN

Barry M. Popkin ([email protected]) is professor of nutrition at University of North Carolina at Chapel Hill.

Increasing urbanization in the developing world has brought a remarkably rapid shift toward a high incidence of obesity and noncommunicable diseases such as diabetes and coronary problems, at a time when large segments of the population still face undernutrition and poverty-related diseases. Obesity and its related diseases, for example, affect 25-50 percent of the population in countries as disparate as Kuwait, Mexico, Thailand, and Tunisia. This “nutrition transition” - a term used to describe shirts in diet, physical activity, health, and nutrition - can be traced to higher incomes, the influence of mass media and food marketing, and a range of changes in the nature of work and leisure.

Where a person stands in the nutrition transition depends on how far that person has moved away from a traditional diet and toward a diet common in the West, with all the accompanying changes in physical activity and body composition. According to this qualitative measure of transition, urban areas throughout the developing world are much further along in the process than rural areas. On a regional basis, most Latin American and Caribbean countries and selected countries in North Africa, the Middle East, and East Asia have shifted the most in nutritional status and dietary and activity patterns. The most promising policy option for remedying the ill effects of this transition appears to be a combination of price policies, education, and specific program actions at the school level.

THE NUTRITION TRANSITION

Urban residents have vastly different lifestyles than rural residents. These lifestyles create their own patterns of food demand and time allocation. The consequences for diets, physical activity, and health have been enormous.

The urban diet. Urban residents obtain a much higher proportion of energy from fats and sweeteners than do rural residents, even in the poorest areas of very low-income countries. Most urban dwellers also eat greater amounts of animal products than their rural counterparts. Urbanites consume a more diversified diet and more micronutrients and animal proteins than rural residents but with considerably higher intakes
of refined carbohydrates, processed foods, and saturated and total fat and lower intakes of fiber.

The figure shows how urbanization changes the fat and sweet content of national diets. Countries that have an urban population share of 75 percent consume about 4 percentage points more energy from vegetable and animal fat and 12 percentage points more energy from sweeteners than countries with an urban population share of 25 percent. This holds true even at low levels of gross national product with an urban population share of 25 percent. This holds true even at low levels of gross national product (GNP). Related research has shown that lower-income countries are able now to afford far more energy from fat than they could in the past at the same level of GNP. Thus, not only are urban diets changing, but they are changing at an earlier stage of economic development.

CALORIE SOURCES AND GNP PER CAPITA, URBANIZATION LEVEL OF 25 AND 75 PERCENT - A

CALORIE SOURCES AND GNP PER CAPITA, URBANIZATION LEVEL OF 25 AND 75 PERCENT - B

Sources: Food balance data from the Food and Agriculture Organization of the United Nations, and GNP data from the World Bank. Results of the author’s regressions on these basic data for 133 countries are shown here.

Increasing incomes partially explain this turn toward fattier foods and sweeteners, but there also seems to be an upward shift in consumer demand for sweeteners and higher-fat products at any given income level. Greater penetration of mass media and modern marketing approaches into the lives of urban residents may account for this shift in food choices. Little is understood, though, about the impact of media and marketing on the nutrition transition. Economic work that relies on income and price changes cannot account for these shifts in behavior.

The ability to produce lower-cost foods that contain oils and sweeteners has facilitated the transition as well. In the last half century, new technologies and new oilseed varieties, for example, have made it much easier to create high-quality, low-cost edible oils as alternatives to much more expensive animal fats.

Urban physical activity patterns. New technologies in work and leisure, along with shifting diets, have increased obesity levels in the urban areas of developing countries. Body composition has changed in tandem with the transformation of the preindustrial agrarian economy into an industrial, urban one. As this transformation has accelerated, the service sector has grown rapidly, capital-intensive processes have come to dominate industrial production, and time-allocation patterns have changed dramatically. Urban work now requires less physical exertion and allows more leisure. Leisure activity has been transformed, particularly by changes in food preparation, production, and processing and by the revolutionary penetration of the mass media into the developing world. Almost all Chinese households, for example, owned at least one working television set by 1997.

Health and nutrition consequences. Changes in diet and physical activity have accelerated the rate of increase in obesity in the developing world. Trends in obesity are not limited to one region, country, or racial or ethnic group. In many cases, such as with women in Egypt and South Africa and across ages and sexes in Mexico, the lower- and middle-income countries have overweight levels that match those of the United States and exceed those of most European countries. Obesity levels are much higher in urban areas: in China and Indonesia adult obesity is twice as prevalent in urban areas as it is in rural areas; in the Congo it is almost six times as prevalent. The Middle East, the Western Pacific, and Latin America have far higher levels of obesity than other developing regions.

Higher-income populations in the developing world also have much higher levels of obesity. This relationship also held a century ago among European and North American populations, but the reverse is now true: the poor in Europe and North America experience far higher levels of obesity and diet-related chronic diseases than their rich counterparts. This reversal has occurred recently among urban Brazilian women and in Chile.

A range of changes in health have accompanied this nutrition transition. Most immediate among these seems to be the emerging epidemic of diabetes, stroke, and hypertension, all diet-related chronic diseases. The evidence from some Asian and Latin American countries is particularly worrying. The economic costs of diet-related noncommunicable diseases in fact have surpassed the cost of malnutrition in China.

A unique issue emerging from this transition is the increasingly frequent double burden of undernutrition and obesity in the same household. The prevalence of households with both overweight and underweight members in Brazil, for example, is 11 percent.

WHERE DO WE GO FROM HERE?

How can the food policy and public health communities, already burdened by the challenges of poverty, undernutrition, and underdevelopment, deal with the seemingly contradictory goal of promoting both greater and lesser food intake? How can they address the prevention of obesity when they focus on undernutrition and poverty?

Part of the answer lies in finding solutions common to both undernutrition and overnutrition and promoting them through education and more direct interventions. Promulgating nutrient-dense fruits and vegetables, for example, would reduce caloric intake and improve micronutrient status. Another such solution is breast-feeding, which offers food rich in nutrients and reduces obesity and coronary heart disease.

Policymakers must also take direct action to reduce obesity at all age levels. Few large-scale efforts have done this successfully, though Scandinavian countries did change their diets and reduce coronary heart disease between 1976 and the 1980s. To do so, the Scandinavians focused on price and other policies, such as fish subsidies, to encourage healthier diets. During the 1990s Singapore reduced child obesity through a combination of changes in school diet and increased fitness and physical activity programming.

A major first step toward a healthier population is awareness of the problems related to the nutrition transition. Many developing countries are realizing the importance of this issue. They must continue their efforts and develop programs and policies for agricultural production, nutrition, food marketing, and education that will help them to successfully confront the nutrition transition and achieve sustainable food and nutrition security.

For further reading see Barry Popkin, “The Nutrition Transition and Its Health Implications in Lower Income Countries,” Public Health Nutrition 1 (1998): 5-21; and Barry Popkin, “Urbanization, Lifestyle Changes and the Nutrition Transition,” World Development 27 (1999): 1905-16.