Fruits and vegetables supply antioxidants other than those you can get from pills, say researchers at the USDA’s Jean Mayer Human Nutrition Research Center on Aging at Tufts University in Boston.

Ron Prior and co-workers fed 36 men and women aged 20 to 40 or 60 to 80 a diet containing ten servings of fruits and vegetables a day. Then they measured the “antioxidant capacity” of the participants’ blood samples by seeing how well the blood deactivated damaging oxidized free radicals in a test tube.

After two weeks, the antioxidant capacity of the participants’ blood rose in both groups, though more consistently in the older people.

“Based on this and other studies, it appears that compounds other than vitamins C and E and carotenoids contribute a major portion of the increase in antioxidant capacity,” says Prior. Among the foods with the highest antioxidant capacity were oranges, cauliflower, and peas.

In a separate study from the Johns Hopkins Medical Institutions in Baltimore, researchers found a higher antioxidant capacity in 83 people who ate eight to ten servings of fruits and vegetables a day than in 40 others who ate fewer servings. —Bonnie Liebman