Decreased consumption of dried mature beans is positively associated with urbanization and nonfatal acute myocardial infarction

Abstract

Beans, Phaseolus vulgaris, are legumes that are thought to have originated from southern Mexico and Central America over 7000 y ago (1); they still form an important part of the staple diet in those regions. For many centuries, beans have remained part of the human diet in several countries on all continents. Black beans or black Spanish beans are the commonest variety in Latin America; they are usually consumed as dried mature beans together with rice. The combination of rice and dried mature black beans (later referred to as beans) supplies various nutrients including essential amino acids, folate, soluble fiber, copper, magnesium, iron, potassium, calcium, zinc, and _-linolenic acid (2–10). Although there are several varieties of beans that occur in different sizes, shapes, and colors, their nutrient composition is quite similar to that of black beans (Table 1). Legumes including beans may protect against cardiovascular disease (CVD)3 through various mechanisms (2,5,10,11). However, epidemiologic data on the association between individual legumes such as beans and peas and CVD are lacking. Beans form the core of the Latin American staple diet and contribute significantly to energy and micronutrient intakes (5–7,12). Despite the recommendation to increase the intake of beans by health organizations (8), their consumption, as well as that of other legumes, has decreased with urbanization (13). This is probably because of the increased availability and advertising of relatively cheap simple carbohydrate diets such as pasta and white bread (7,13). As expected, these trends are likely to be responsible for the increased obesity and the slow emergence of cardiovascular and other chronic diseases in many Latin American countries, including Costa Rica, where myocardial infarction (MI) accounts for 47.2% of CVD (14,15). Some of the few studies that have investigated the nutrients in beans [e.g., fiber (16 –18), folate (19), magnesium (20,21), and copper (22)], suggest inverse associations with CVD. Unlike soybeans and peanuts, the role of other legumes (e.g., beans) in CVD has not been reported. We therefore investigated, in a large incident case-control study in Costa Rica, whether eating beans is associated with risk of MI and explored potential mechanisms for such an association.