Keep eating those bean burritos. One serving of black beans a day helps stave off heart disease, researchers have confirmed in a new study. Yet consumption of this legume has fallen among Latin Americans and among Hispanics in the United States, both of which have traditionally eaten beans as a staple.

Researchers have known for several years that legumes, including peas, nuts, and all beans, contribute to heart health. However, prior studies focused on U.S. populations, which tend to consume fewer beans and more of other legumes, such as peanuts. The new study, published in the July Journal of Nutrition, specifically links black beans to lower risk of heart attack. These beans are a major nutrient source in Latin American and Hispanic diets.

Hannia Campos of Harvard University and her colleagues interviewed 2,118 individuals in Costa Rica who had suffered nonfatal heart attacks. They compared these people with an equal number of heart-healthy individuals, matching each heart attack sufferer with a healthy person of the same age, sex, and area of residence. The research team collected data on these individuals' diets, physical-activity levels, socioeconomic statuses, and medical histories.

Costa Ricans who ate one serving, or a third of a cup, of beans per day were 38 percent less likely to have suffered a heart attack than were those who ate beans less than once a month. Beans protected the study participants against heart disease independently of other risk factors, such as obesity, physical activity, and smoking.

Beans contain numerous nutrients known to ward off heart disease, says Campos. "It's a very good package in terms of a single food," she says. Like other legumes, black beans contain folate, magnesium, alpha-linolenic acid, vitamin B6, and fiber. Beans make up a large portion of Costa Ricans' intake of these protective nutrients. For instance, beans make up 25 percent of their total fiber and 17 percent of their folate consumption, says study coauthor Edmond Kabagambe, also of Harvard.

Despite beans' healthy properties, consumption of these legumes is lower in people living in cities, the research team found. Urban populations in Costa Rica ate 24 percent less beans than did people living in rural areas.

City dwellers tend to seek "easy meals" of processed foods, which are often high in fat, carbohydrates, and sugar, says Kabagambe. "They eat less of food that takes longer to prepare," he says, such as beans.

Campos says that bean consumption has decreased among Latin Americans and Hispanics partly because of increased urbanization of these populations and partly because beans have acquired a negative image among these people.

"They're seen as the food of the poor," she says. "As soon as people have a better income in any way, beans are the first thing to go."

Urbanization has climbed in Latin America, rising from half the population in the 1950s to about 70 percent today, says Roberto Uauy of the University of Chile in Santiago, who has studied dietary trends in Latin America. In some nations, such as Brazil, as many as 85 percent of citizens live in cities. Sao Paulo, Brazil, and Mexico City boast the largest urban populations in the world.

Hispanic immigrants to the United States also tend to move into cities, notes Katherine Tucker, a nutrition researcher at Tufts University. Moreover, as successive generations of Hispanics integrate with the culture of their new country, they move away from traditional foods such as beans.

"In doing so, they're losing a lot of basic vitamins and minerals that are in those good-quality foods," Tucker says.

The finding of Campos and her team will encourage nutritionists to emphasize the value of traditional meals, says Uauy. He also points to the value of corn tortillas, a Mexican staple that when combined with beans provides the full range of proteins found in red meat. "We are now recognizing that traditional food components, traditional diets, have importance for people's health," he says.

Beans aren't only important for Hispanics and Latin Americans, emphasizes Tucker. She asserts that all Americans would benefit from eating more beans.

"Inclusion of beans is a very straightforward way to improve diet quality," she says.

References:

Kabagambe, E.K. . . . and H. Campos. 2005. Decreased consumption of dried mature beans is positively associated with urbanization and nonfatal acute myocardial infarction. Journal of Nutrition 135(July):1770-1775. Abstract available at http://www.nutrition.org/cgi/content/abstract/135/7/1770.

Further Readings:

Raloff, J. 1998. Magnesium: We don't appear to be getting enough. Science News Online (Aug. 29). Available at http://www.sciencenews.org/pages/sn_arc98/8_29_98/food.htm.

______. 1998. Soya-nara, heart disease. Science News 153(May 30):348-349.

Sources:

Hannia Campos
Department of Nutrition
Harvard School of Public Health
Building II, Room 353A
655 Huntington Avenue
Boston, MA 02115

Edmond Kabagambe
Department of Nutrition
Harvard School of Public Health
Building SPH2, Room 304
Boston, MA 02115

Katherine L. Tucker
Dietary Assessment and Epidemiology Research Program
Jean Mayer USDA HNRCA at Tufts University
711 Washington Street
Boston, MA 02111-1524

Ricardo Uauy
Public Health Nutrition
London School of Hygiene & Tropical Medicine and INTA University of Chile
Keppel Street
London WC1E 7HT
United Kingdom