Health experts say that eating a healthful diet can reduce your risk of heart disease, among other things. But what does eating a healthful diet really mean? Research recently published in Archives of Internal Medicine looked at how consumption of one type of food—legumes, which include beans, peas, and peanuts—may be related to risk of coronary heart disease.

About the study

Researchers from Tulane University examined the health records of 9632 male and female participants (out of an original 14,407) from the First National Health and Nutrition Examination Survey Epidemiologic Follow-up Study, which was conducted initially between 1971 and 1975. The original study included a survey of health and dietary habits, along with a physical examination. At the time of the original survey, the participants were all between the ages of 25 and 74 and were all free of cardiovascular disease.

Follow-up data were collected on available participants between 1982 and 1984, in 1986, 1987, and 1992. Each follow-up contact included screening for cardiovascular disease and information about dietary habits. One of the questions on the dietary questionnaire asked how often participants ate "dry beans and peas like pinto beans, red beans, black-eyed peas, peanuts and peanut butter" over the past three months.

The findings

Using the data that had been collected between 1971 and 1992, researchers were able to look at which study participants had developed coronary heart disease over that 21-year period. They found that people who ate legumes four or more times per week had a 22% lower risk of developing coronary heart disease than people who ate legumes less than once per week. From these results, the researchers concluded that eating legumes probably provided people some protection against heart disease.

Did eating beans, peas and peanuts prevent people in the study from getting heart disease?

Unfortunately, we're still not sure. People eat a variety of foods every day containing countless nutrients and compounds that may affect their risk for any number of diseases. In addition, genetics and other health habits, such as smoking and exercise, play a role in the development of heart disease. More likely, eating legumes, which are rich in bean protein, water-soluble fiber, calcium, magnesium and potassium, was one of a number of health and dietary habits that protected these people from heart disease.

Other research also supports the theory that beans and other legumes may provide some protection from heart disease. Clinical studies have shown that the soluble fiber and protein found in legumes can lower cholesterol levels and blood pressure—both of which are thought to reduce the risk of heart disease. And finally, legumes are a major source of folate—a B vitamin that lowers blood levels of homocysteine, which may in turn reduce the risk of heart disease.

Although these findings indicate that consuming more legumes may provide protection against heart disease, there is no information about portion size. Portion size information was not collected. Instead, the researchers estimated how many legumes people ate based on a 24-hour dietary recall survey. People's perceptions of what one serving size looks like may vary significantly, making it even more challenging to accurately measure consumption.

Many studies of nutrition and disease try to tease out the role of individual nutrients in relationship to specific diseases. The authors of this study, however, have done a valuable service by trying to identify a single food that can be helpful in preventing heart disease. Most people find it easier to think about diet in terms of foods rather than the individual nutrients within them, such as fiber or calcium. Studies that attempt to identify foods, rather than individual nutrients, that may help prevent disease are likely to have a more positive impact on people's food choices.

How does this affect you?

This study provides evidence that beans and other legumes should be part of a healthful diet, particularly in adults (the study didn't involve people under age 25). Other than an occasional gas pain from eating too many at once, there is no downside to eating legumes. They contain a variety of nutrients, are often less expensive than comparable protein sources, and are relatively simple to prepare.

So, if you don't eat legumes regularly, try adding them into your diet. And if you do eat legumes regularly, keep it up. Together with other healthy habits, such as an overall healthy diet, regular exercise, not smoking, and drinking alcohol only in moderation, it may be one more factor that helps you avoid heart disease.