Pinto Bean Consumption Lowers Cholesterol More Than Oatmeal

MESA, Ariz. Esther Martinez has eaten pinto beans most of her life and admits her family used to use lard when they prepared refried beans. "Now, I eat pinto beans boiled with fresh tomato, whole onion and green chilies or refry them with cheese in canola oil," said Martinez. Little did she know that eating pinto beans, prepared without lard, can help lower her cholesterol level, even more so than eating oatmeal, according to research conducted by Arizona State University Nutrition scientists. When Martinez learned that her cholesterol was getting close to 200, though, and was pre-diabetic in 2005, she knew she had to do something to lose weight to address the threat of diabetes or heart disease before it was too late. As an office specialist senior at Arizona State University's Polytechnic campus, she saw the bean study as an opportunity to improve her health. Donna Winham, ASU assistant professor of nutrition, was looking for subjects who met certain criteria, such as having higher cholesterol and/or being moderately insulin resistant (pre-diabetic), like Martinez. "Beans are considered a very affordable, functional, healthy food rich in protein, complex carbohydrates, fiber, minerals and phytochemicals, which are non-nutritive plant chemicals that have protective or disease preventive properties," said Winham. In 2005 and 2006, Winham and colleague Andrea Hutchins conducted their 24-week experiment to understand the impact of long-term legume consumption on biomarkers for heart disease and type 2 diabetes risks. In their research they employed canned pinto beans and black-eyed peas and carrots as the placebo. "We chose these beans to study because they are a common legume variety consumed around the world as part of traditional diets," said Winham whose research focuses on international nutrition, functional foods and childhood nutrition. The 17 subjects who participated in the nine-month study were asked to eat a half cup of pinto beans, black-eyed peas and carrots every day for eight weeks each. Initial results from the study suggested that pinto beans were effective at lowering overall cholesterol levels and the black-eyed peas appeared to lower insulin levels significantly. "However, when we increased the size of the study group, the results changed," said Winham. "The pinto beans were still very effective at lowering cholesterol levels by more than 8 percent, but the black-eyed peas no longer showed an effect on glucose/insulin levels and at no point did the pinto beans show an effect on glucose or insulin either. Researchers attributed the results to the quantity of the product consumed and believe that increased quantities of the black-eyed peas would indeed have an effect on biomarkers. "The benefit of the study is that it proves that long-term consumption of pinto beans does have a significant impact on lowering the risk of heart disease," said Winham. "A diet that incorporates beans might be as productive as taking a statin." While pinto beans have been proven to be effective, Winham and Hutchins stress that legume variety is key in the diet. "Different beans are recognized for achieving different effects on biomarkers, so it's important to incorporate an assortment into the diet," said Winham.