Free trade, the food industry and obesity: How changes in US – Mexico food trade contributed to an epidemic

Like other countries, Mexico has seen a dramatic increase in obesity and diabetes in the last decade. While obesity has many causes that operate at multiple levels, this report examines how new trade agreements can lead to changes in the practices of multinational companies that can then contribute to health problems. It also illustrates how these global changes interact with national and local trends to influence health.

At the global level, the food market integration between Mexico and the United States that began in the 1980s accelerated after the two countries signed the North American Free Trade Agreement (NAFTA) in 1994 (1). NAFTA removed trade barriers between the US, Canada and Mexico, making it easier for Mexico to export flowers and tropical fruits, for example, and for US companies to sell Mexicans low-cost corn, processed food and other goods and to invest US dollars in the Mexican food industry. Between 1988 and 1997, U.S. foreign direct investment in the Mexican food processing industry increased from US $ 210 million to US $ 5.3 billion, a 25-fold increase (1). This increase had a major impact on the types of food available in Mexico.

Most NAFTA-inspired US foreign direct investment in the Mexican food industry supported production of processed food. Between 1995 and 2003, sales of processed food increased by 5 to 10% annually (1). In the same period, the Mexican diet changed considerably. Between 1992 and 2000, for example, calories from carbonated soft drinks increased by almost 40%, from 44 to 61 Kcal per capita per day. By 2002, the average Mexican was drinking more Coca Cola servings per year, 487, than US residents, who drank 436 8- ounce serving (1).

Increased globalization and consolidation of the Mexican retail food sector and the growing consolidation of supermarkets affected others sectors of society, including agriculture, where small farmers had trouble selling to large supermarkets (2). As a result, many left their farms and moved to the city, leading to more urbanization, decreased access to fresh foods and loss in family and community food self-sufficiency.

How did these changes influence food intake? Between 1988 and 1999, the total energy intake from fat in Mexico increased from 23.5% to 30.3 % (1,3). The increase in urban Mexico City was 32%, compared to the poorer more rural South, where it was only 22 % (3). In this same period, the national prevalence of overweight/obesity increased from 33% to 59%, a 78% increase (4). The overall prevalence of diabetes in Mexico increased from 8.8% in 1993 to 11.4% in 1999, a 30% increase.

In Mexico and other developing nations, urbanization can contribute to higher prevalence of obesity by increasing access to energy-dense fatty foods, especially for low socioeconomic populations groups moving from rural areas (5). Between 1970 and 2000, the proportion of the Mexican population living in urban areas increased from 58% to 75%, the highest rate in Central America. By 2000, Mexico City, the capital, was the second largest city in the world. Furthermore, longitudinal studies suggest that the rapid transition from rural to urban and from high rates of early malnutrition to later childhood overnutrition serve as independent risk factors for obesity, diabetes and cardiovascular disease in adulthood (6). Thus, the particular pattern of economic development that Mexico pursued facilitated gains in weight, especially in the growing urban low income population. When food markets then made high calorie low nutrient foods readily available to newly urbanized, mostly sedentary people, the stage was set for rapid weight gain.

Impact on Health

Growing rates of diabetes, fueled by the epidemic of obesity, consumed larger portions of the nation’s health care budget, depriving resources from other health problems. In 2000, the annual cost of diabetes care per person per year in Mexico was US $607 and one study estimated that total diabetes costs in Mexico in 2000 were US $15.1 billion (7).

At the municipal level, changes in the economy and food availability led to price increases. Between 1992 and 2000, in part as a result of economic changes precipitated by NAFTA, the cost in pesos per megacalorie of food tripled in both urban and rural areas but remained twice as high in urban than rural areas – making low-cost low-nutrient foods more attractive (8). Aggressive marketing of soft drinks and other high calorie, low nutrient snack foods by global and national beverage makers, especially to urban children and young adults, the fastest growing segment of the population and industry’s best hope for increased market share, further encouraged consumption (1). Cities, with dense populations, established media markets and numerous retail outlets, made particularly suitable venues for advertising. Often ad campaigns were planned by increasingly globalized advertising companies (1). In Mexico City, the first McDonald’s restaurant opened in the early 1980s; twenty years later there were 200 Golden Arches in the city (9).

At the neighborhood level, rapid urbanization, loss of green space, the decline in physical labor and high crime rates combined to discourage physical activity, further contributing to obesity. This social environment where diets included more high calorie low nutrient foods and less fresh produce as well as reduced opportunities for physical activity led to weight gain.

Genetic characteristics of the Mexican population also contributed to rates of obesity but it was environmental exposure to a rapidly escalating obesogenic environment that precipitated the phenotypic expression of genotypic vulnerability (10). Moreover, those with Indian ancestry, at higher risk of a genetic predisposition to diabetes, were often concentrated in the low-income urban and rural areas as a result of socioeconomic and ethnic segregation, precisely those areas where food availability was changing most rapidly. For example, a study of diabetes prevalence in a low-income barrio in Mexico City found that 59% of the population had some Native American ancestry (9). Thus, global, national and municipal factors intersected to create a new environment for a specific population with a higher genetic risk for obesity and diabetes.

This case also shows how changes in the practices of global food companies – e.g., increased exports to developing nations; aggressive marketing of high calorie, low nutrient foods and beverages; and expansion of retail outlets to reach diverse sectors of the population– created an obesogenic environment that contributed to the explosive growth of the epidemics of obesity and diabetes in a genetically vulnerable population. Rising rates of obesity and diabetes affected both urban and rural Mexico, but as a result of dense urban markets that facilitated aggressive food advertising, a growing urban middle class that could afford more processed food and a working class population whose food choices became more constrained and less healthy and the declines in physical activity, these epidemics left a distinct footprint in Mexico’s cities. Reversing these trends will require intervention at the multiple levels that have triggered the changes.

Popular mobilization is one potential source of change. In Mexico last year, corn tortillas, a crucial source of calories for 50 million poor people, doubled in price, precipitating protests, demonstrations and eventually government price controls. Whether similar global food changes will lead to a Mexican food justice movement that takes on hunger, obesity and the growing corporate control of food remains to be seen.

By Nicholas Freudenberg, Hunter College, City University of New York.


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