Largest USDA study of food antioxidants reveals best sources

Artichokes and beans may not be at the top of your list of favorite foods, but when it comes to antioxidants, these veggies earn a coveted place. They are among a growing variety of foods found to contain surprisingly high levels of these disease-fighting compounds, according to a new USDA study, which researchers say is the largest, most comprehensive analysis to date of the antioxidant content of commonly consumed foods.

In addition to confirming the well-publicized high antioxidant ranking of such foods as cranberries and blueberries, the researchers found that Russet potatoes, pecans and even cinnamon are all excellent, although lesser-known, sources of antioxidants, which are thought to fight cancer, heart disease and Alzheimer's. The study appears in the June 9 print edition of the Journal of Agricultural and Food Chemistry, a peer-reviewed publication of the American Chemical Society, the world's largest scientific society.

"The bottom line is the same: eat more fruits and veggies," says Ronald L. Prior, Ph.D., a chemist and nutritionist with the USDA's Arkansas Children's Nutrition Center in Little Rock, Ark., and lead author of the study. "This study confirms that those foods are full of benefits, particularly those with higher levels of antioxidants. Nuts and spices are also good sources."

The new study is more complete and accurate (thanks to updated technology) than previous USDA antioxidant data and includes more foods than the previous study, the researchers say. They analyzed antioxidant levels in over 100 different foods, including fruits and vegetables. In addition, the new study includes data on spices and nuts for the first time.

Among the fruits, vegetables and nuts analyzed, each food was measured for antioxidant concentration as well as antioxidant capacity per serving size. Cranberries, blueberries, and blackberries ranked highest among the fruits studied. Beans, artichokes and Russet potatoes were tops among the vegetables. Pecans, walnuts and hazelnuts ranked highest in the nut category.

Although spices are generally consumed in small amounts, many are high in antioxidants. On the basis of antioxidant concentration, ground cloves, ground cinnamon and oregano were the highest among the spices studied.

Prior says that the data should prove useful for consumers seeking to include more antioxidants in their diet. But he cautions that total antioxidant capacity of the foods does not necessarily reflect their potential health benefit, which depends on how they are absorbed and utilized in the body. Researchers are still trying to better understand this process, he adds.

Currently, there are no government guidelines for consumers on how many antioxidants to consume and what kind of antioxidants to consume in their daily diet, as is the case with vitamins and minerals. A major barrier to such guidelines is a lack of consensus among nutrition researchers on uniform antioxidant measurements. Scientists will soon attempt to develop such a consensus at the First International Congress on Antioxidant Methods, held June 16-18 at the Caribe Royale Hotel and Conference Center in Orlando, Fla., with the ultimate goal of developing better nutritional data for consumers. ACS is the principal sponsor of the meeting.

For now, USDA officials continue to encourage consumers to eat a variety of fruits and vegetables for better health.

BEST SOURCES OF FOOD ANTIOXIDANTS: TOP 20 FRUITS, VEGETABLES AND NUTS (AS MEASURED BY TOTAL ANTIOXIDANT CAPACITY PER SERVING SIZE)

Rank

Food item

Serving size

Total antioxidant capacity per serving size

1

Small Red Bean (dried)

Half cup

13727

2

Wild blueberry

1 cup

13427

3

Red kidney bean (dried)

Half cup

13259

4

Pinto bean

Half cup

11864

5

Blueberry (cultivated)

1 cup

9019

6

Cranberry

1 cup (whole)

8983

7

Artichoke (cooked)

1 cup (hearts)

7904

8

Blackberry

1 cup

7701

9

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

16-jun-2004