Taco Bell announced Thursday that it will using a canola oil with zero grams trans fats in its U.S. restaurants. All of Taco Bell's 5,000 single-brand restaurants will be using the oil by April, which means 15 items on the Taco Bell menu will not contain any trans fats.

The items that will not have trans fats include the Crunchy Beef Taco, the Taco Supreme, Cinnamon Twists, the steak Gordita Supreme, Grilled Steak Soft Taco, Spicy Chicken Taco and some chalupas. Several items on the Taco Bell menu, like the chicken and steak Gordita Bajas and the chicken Gordita Supreme, already contain zero grams trans fats.

The Grilled Stuft Burrito and some other items will still contain some trans fats.

Taco Bell started working on the plan more than two years ago using consumer taste tests to preserve the items' taste.

Warren Widicus, Taco Bell's chief food innovation officer, tells the AP, "This is something we've been working on for over two years, and we just believe it's the right thing and the right changes to make in our products."

More than 100 Taco Bell restaurants have already gone through the changes.