The FDA banned the use of red dye No. 3 in foods and medicines sold in the U.S. because it has been shown to cause cancer in rats. The action highlights the limits of a federal law known as the Delaney clause.

"The Delaney Clause is clear; the FDA cannot authorize a food additive or color additive if it has been found to cause cancer in humans or animals. Evidence shows cancer in laboratory male rats exposed to high levels of FD&C Red No.3," said Jim Jones, the FDA's deputy commissioner for human foods.

The U.S. on Wednesday banned the use of a synthetic food dye that gives some candies, cakes and certain oral medications a cherry-red color, following evidence that the dye causes cancer in laboratory rats.