Cities and the Health of the Public

6. Food, Nutrition, and the Health of Urban Populations

106 6 Food, Nutrition, and the Health of Urban Populations Ming-Chin Yeh and David L. Katz Introduction In the past century, Western nations have witnessed a dramatic transformation in the impact of nutrition on the health of the public. In the early decades of the 20th century, and before, food and nutrient deficiencies were the prevailing scourges. Now the problem of nutritional excess has overtaken deficiency as a leading threat to health in the United States and increasingly throughout much of the world.1, 2 According to the U.S. Census Bureau, 80% of Americans live in central cities and their suburbs. Therefore, the health problems of the nation are concentrated among these metropolitan populations, which differ from nonmetropolitan populations in several ways. For example, the foreign born are more likely than nativeborn U.S. residents to live in central cities (44% vs. 26%). Overall, 12% of U.S. residents are foreign born, whereas in cities like Miami, NewYork, San Francisco, and Los Angeles, more than a third of the residents are foreign born.3 In addition, U.S. urban populations have higher proportions of African Americans, Hispanics, and Asians than nonurban areas, as well as a higher proportion of people living in poverty. Both ethnicity and income are associated with increased mor­bidity and mortality.4 As the following discussion reveals, the nutritional problems that city dwellers face are a consequence of the composition of urban populations, especially the disproportionate representation of poor people, and the unique characteristics of the urban food system. This chapter provides an overview of a range of nutrition issues that are related to health in a variety of urban settings. While the focus is on nutrition, we also consider physical activity because of the important role it plays in obesity. This chapter focuses on several major areas: the current epidemiology of public Food, Nutrition, and the Health of Urban Populations 107 health nutrition, with an emphasis on the obesity epidemic; the relationship between neighborhood characteristics and dietary and chronic disease risks; challenges to staying healthy in an urban setting; and strategies to improve health in urban settings. We conclude with recommendations for future directions in research and intervention. Current Epidemiology of Public Health Nutrition Dietary factors contribute substantially to the burden of preventable illnesses. Epidemiological studies have shown consistently that high-fat foods are associated with obesity as well as several chronic diseases, including cardiovascular disease, diabetes, and certain types of cancer. Dietary patterns, however, that include high consumption of fruits and vegetables, whole-grain foods, and limited saturated fat intake from red meats are associated with decreased risk for these chronic conditions .5 Cardiovascular disease (e.g., coronary heart disease and stroke), cancer, and diabetes account for nearly two-thirds of all deaths in the United States and approximately $700 billion in direct and indirect economic costs.6 Although tobacco use is the leading cause of death, accounting for 18.1% of U.S. deaths in 2000, poor diet and physical inactivity come in second, accounting for 15.2% of U.S. deaths.7 Obesity Epidemic The prevalence of obese (defined as a body mass index, or BMI, at or above 30 kg/m2 ) and overweight (25 kg/m2 ≤ BMI 27.3 kg/m2 ) increased as food insecurity increased, from 34% to 41% to 52% for those who were food secure, mildly food insecure, and moderately in­secure, respectively. After adjusting for potential confounding variables, such as demographic and life-style factors, food insecurity remained a significant predictor of overweight status. A possible explanation of this phenomenon is that after people are deprived of food temporarily, they develop a tendency to binge eat when food is plentiful again, as is evidenced by diet program participants.100 Binge eating has been shown to result in weight gain.101 Thus, owing to an unfortunate food acquisition cycle—the “feast and famine” cycle—the food stamp recipients were found to have a high prevalence of overweight due, in part, to this involuntary, temporary 114 Part III: Local and Global Perspectives on Changing Cities food restriction.102 In addition, individuals from food-insecure households often have limited financial resources103 and are forced to consume more low-cost but energy-dense foods to maintain adequate energy intake.104 This overconsumption of energy-dense foods could lead to higher percentage of fat and total energy intakes,105 the major factors associated with obesity. Thus, food-energy...