Burger King said Friday it would use trans-fat-free cooking oil at all its U.S. restaurants by the end of next year, following in the footsteps of other leading fast-food restaurants.

The world’s second largest hamburger chain said it already was using zero trans-fat oil in hundreds of its more than 7,100 U.S. restaurants nationwide.

Burger King is known for its flame-broiled burgers, but uses cooking oil for its french fries and most of its chicken products.

In tests, consumers determined that more than a dozen items cooked in the new oil tasted the same or better than products cooked in the trans-fat oil, the company said. Miami-based Burger King Corp. said two trans-fat-free oil blends passed tests. If adequate supply becomes available, the U.S. rollout of the oils could be completed sooner than 2008, the company said.