Antioxidants work to neutralize harmful free radicals in the body. Free radicals, which are formed as byproducts of cellular functions, can attack and damage healthy cells by initiating oxidation reactions. Scientists speculate that these oxidation reactions may be a causative factor for diseases, such as cancer and cardiovascular disease, explains the Mayo Clinic. Black beans, kidney beans and small red beans are excellent sources of antioxidants, and therefore a diet that includes these beans may be beneficial to an individual's health.
ScienceDaily.com summarizes the results of a study on the antioxidant activity of various types of beans. The study appeared in the Dec. 31, 2003, issue of the "Journal of Agricultural and Food Chemistry," and Dr. Clifford W. Beninger of the University of Guelph in Ontario, Canada was the lead investigator. Beninger compared the antioxidant activity of 12 different types of dry beans. He found that black beans had more activity per gram than any of the other beans in the study. The second highest antioxidant activity went to red beans followed by brown, yellow and white in the top five. A class of flavonoid compounds called anthocyanins was largely responsible for the antioxidant activity of the black beans.
The Oxygen Radical Absorbance Capacity (ORAC) score for a particular food is a way to measure the effectiveness of that food as an antioxidant. This method of evaluating antioxidant capacity was developed by the National Institutes of Health. Kidney beans receive an ORAC score of 8,459 which means that they have a high capacity to absorb free radicals and therefore may be of value in preventing certain diseases. Kidney beans have a higher antioxidant capacity than blueberries with their ORAC score of 6,552, a food thought to confer many antioxidant health benefits.
Small Red Beans
The June 21, 2004, edition of the "Los Angeles Times" described the results of research on the antioxidant content of more than 100 different foods including fruits, vegetables, nuts, spices, breads, cereals and beans. The research was carried out by Dr. Ronald L. Prior and his colleagues at the U.S. Department of Agriculture's Arkansas Children's Nutrition Center in Little Rock and published in the "Journal of Agricultural and Food Chemistry." The results indicated that small red beans ranked first, containing the highest concentration of antioxidants per serving of all the foods tested. The method used by Prior to assay antioxidant capacity placed red kidney beans third and pinto beans fourth in antioxidant concentration. It is noteworthy that three of the top 10 antioxidant foods were beans.