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 Parkinson's disease.

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 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:

1 Small Red Bean Half cup 13727

2 Wild blueberry 1 cup 13427

3 Red kidney bean Half cup 13259

4 Pinto bean Half cup 11864

5 Blueberry (cultivated) 1 cup 9019

6 Cranberry 1 cup 8983

7 Artichoke (cooked) 1 cup (hearts) 7904

8 Blackberry 1 cup 7701

9 Dried Prune Half cup 7291

10 Raspberry 1 cup 6058

11 Strawberry 1 cup 5938

12 Red Delicious apple One 5900

13 Granny Smith apple One 5381

14 Pecan 1 ounce 5095

15 Sweet cherry 1 cup 4873

16 Black plum One 4844

17 Russet potato (cooked) One 4649

18 Black bean (dried) Half cup 4181

19 Plum One 4118

20 Gala apple One 3903