June 17, 2004 -- Blueberries may be the poster children for antioxidant abundance, but a new study suggests the humble bean may be a more deserving candidate.
The largest and most advanced analysis of the antioxidant content of common foods to date shows that disease-fighting antioxidants may be found in unexpected fruits and vegetables, such as beans, artichokes, and even the much-maligned Russet potato.
Researchers found that small red beans contain more disease-fighting antioxidants than both wild and cultivated blueberries, which have been heralded in recent years for their high antioxidant content. In fact, three of the top five antioxidant-rich foods studied were beans.
The study also shows that nuts and spices, such as ground cloves, cinnamon, and oregano, are rich in antioxidants, although they are generally consumed in much smaller amounts than fruits and vegetables.
Antioxidants are believed to help prevent and repair oxidative stress, a process that damages cells within the body and has been linked to the development of cancer, heart disease, Alzheimer's disease, and .
Ranking Antioxidant-Rich Foods
The study, which appears in the June 9 issue of the Journal of Agricultural
and Food Chemistry, used updated technology to assess the antioxidant content of more than 100 foods, including fruits, vegetables, cereals, breads, nuts, and spices.
Each food was analyzed for antioxidant concentration and ranked according to antioxidant capacity per serving size. But researchers note that the total antioxidant capacity of a food does not necessarily reflect their potential health benefit.
"A big factor in all of this is what happens in the digestion and absorption process," says Researcher Ronald Prior, PhD, a chemist and nutritionist with the USDA's Arkansas Children's Nutrition Center in Little Rock, Ark. "With some of these compounds, it appears that even though they have a high antioxidant capacity, they may not be absorbed."
Cranberries, blueberries, and blackberries were ranked highest among the fruits studied. Beans, artichokes, and Russet potatoes were tops among the vegetables.
Pecans, walnuts, and hazelnuts were the winners in the nut category, and ground cloves, cinnamon, and oregano were the top three antioxidant-rich spices.
Here's the list of the top 20 food sources of antioxidants, based on their total antioxidant capacity per serving size:
Total antioxidant capacity per serving size
Small Red Bean (dried)
Red kidney bean (dried)
1 cup (whole)
1 cup (hearts)
Red Delicious apple
Granny Smith apple
Russet potato (cooked)
Black bean (dried)
Researchers also found that cooking method also had a significant effect on the antioxidant content of the foods tested, but those effects were not consistent.
For example, cooked Russet and red potatoes had much lower antioxidant levels than those found in raw potatoes. Boiling also decreased antioxidant levels in carrots, but cooking tomatoes increased their antioxidant content.
Putting Antioxidants in Perspective
Registered dietitian David Grotto says he was amazed to see that unexpected foods, such as beans, potatoes, and artichokes, were so highly ranked by the study.
"With the onslaught of 'no carbs' going on out there, it's nice that we can show that the potato brings more to the table than just carbohydrates," says Grotto, who is director of nutrition at Block Center for Integrative Cancer Care in Evanston, Ill.
"The message here is diverse diet is still optimal," Grotto tells WebMD. "You don't want to be on the all-red-bean diet because it may have the unique set of antioxidants that are attributed to beans, but it may not have many of the antioxidants that you would find in a wild blueberry."
Nor does it mean that you should limit your diet to only the foods that made the study's top 20 list or start popping antioxidant supplements.
"What we're discovering is that we only know about a thimbleful of all the antioxidants that are probably within foods," says Grotto, who is also a spokesman for the American Dietetic Association. "What's unique about eating foods vs. supplements is that there is always more bang for the buck in eating the foods, and you get a lot of those compounds that we really don't fully understand the benefits of yet."
- Grotto recommends the following tips to incorporate more antioxidant-rich foods into your diet:
- Make bean cubes. Process leftover beans with a little vegetable broth in a food processor until it forms a thin paste. Pour into ice cube trays, and then use the frozen cubes to thicken soups and sauces.
- Substitute beans for meats. Most recipes that call for ground or cubed meats, such as stews and casseroles, also work with beans like lentils, chickpeas, or black beans in the starring role.
- Be berry sneaky. Toss a handful of berries on your breakfast cereal or blend them into fruit smoothies for a healthy breakfast or snack.
But don't despair if your favorite food didn't make the list. Antioxidants are only one piece of the healthy eating puzzle.
"Some of those foods that are low in antioxidants may have other positive benefits, such as fiber, minerals, and other nutrients that are important," says Prior.