BOSTON, Aug. 20 (UPI) -- The compounds that give color to most red, purple and blue produce -- anthocyanins -- may slow the growth of colon cancer cells, a U.S. study showed.

Lead author Monica Giusti of Ohio State University tested the anti-cancer effects of anthocyanin-rich extracts from a variety of fruits and vegetables including grapes, radishes, purple corn, chokeberries, bilberries, purple carrots and elderberries.

The researchers found that the amount of anthocyanin extract needed to reduce cancer cell growth by 50 percent varied among the plants -- extract derived from purple corn was the most potent, while chokeberry and bilberry extracts were nearly as potent as purple corn.

Radish, the least potent, took nine times as much of the compound to cut cell growth by 50 percent.

"All fruits and vegetables that are rich in anthocyanins have compounds that can slow down the growth of colon cancer cells, whether in experiments in laboratory dishes or inside the body," Giusti said in a statement.

Giusti and colleagues presented the findings at the national meeting of the American Chemical Society in Boston.