WASHINGTON (AP) _ Popular foods like pie crusts, frostings and microwave popcorn will be largely rid of artery-clogging trans fats after a decision by the Obama administration to phase them out over the next three years.

The Food and Drug Administration on Tuesday ordered food companies to phase out artificial trans fats, calling them a threat to public health. Consumers aren’t likely to notice much of a difference in their favorite foods, but the administration says the move will reduce coronary heart disease and prevent thousands of fatal heart attacks every year.

Scientists say there are no health benefits to the fats, which are used in processing food and in restaurants, usually to improve texture, shelf life or flavor. They can raise levels of “bad” cholesterol and lower “good” cholesterol, increasing the risk of heart disease, the leading cause of death in the United States.

The fats are created when hydrogen is added to vegetable oil to make it more solid, which is why they are often called partially hydrogenated oils.

Once a staple of the American diet _ think shortening and microwave popcorn _ most artificial trans fats are already gone. The FDA says that between 2003 and 2012, people ate about 78 percent less trans fat as food companies began using other kinds of oils to replace them.

But some foods still have them, and the FDA says those trans fats remaining in the food supply are a health concern. Among the foods that commonly contain trans fats: frostings, pie crusts, biscuits, microwave popcorn, coffee creamers, frozen pizza, refrigerated dough, vegetable shortenings and stick margarines.

To phase the fats out, the FDA made a preliminary determination in 2013 that partially hydrogenated oils no longer fall in the agency’s “generally recognized as safe” category, which covers thousands of additives that manufacturers can add to foods without FDA review. The agency made that decision final Tuesday, giving food companies until June 2018 to phase them out.

Now that trans fats will be off the list of safe additives, any company that wants to use them will have to petition the agency to allow it. That would phase them out almost completely, since not many uses are likely to be deemed as safe.

Still, food companies are hoping for some exceptions. The Grocery Manufacturers Association, the main trade group for the food industry, is working with companies on a petition that would formally ask the FDA if it can say there is a “reasonable certainty of no harm” from some specific uses of the fats. It provided no specifics.

But the association said in a statement that the FDA’s three-year compliance period “minimizes unnecessary disruptions to commerce.”

Trans fats are widely considered the worst kind of fats for your heart, even worse than saturated fats, which also can contribute to heart disease. Over the years, they have been used in foods that need solid fat for texture, or in those that need a longer shelf life or flavor enhancement. They also have been used by restaurants for frying.

The industry’s reduction in trans fats was helped along by FDA’s decision to force labeling of trans fats on food packages in 2006. But foods that list trans fat content as zero can still have very small amounts, since companies are allowed to round less than half of a gram of trans fat to zero on the package label.

Susan Mayne, director of the FDA’s Center for Food Safety and Applied Nutrition, says those hidden amounts can still “add up to a considerable intake of trans fats if you look at the overall diet.”

For now, the agency is recommending that consumers take a look at ingredient lists on packaged foods to make sure they don’t contain partially hydrogenated oils. Once the three-year compliance period is up, none of those ingredients would be allowed unless FDA specifically approves them.

The advocacy group Center for Science in the Public Interest first petitioned FDA to ban trans fats 11 years ago. The group’s director, Michael Jacobson, says the decision to phase them out “is probably the single most important thing the FDA has ever done for the healthfulness of the food supply.”

Also contributing to the decline over the years are local laws that restrict them in restaurants, such as those in New York City and California. Large retailers like Wal-Mart have reduced the amount they sell.

The FDA has not targeted small amounts of trans fats that occur naturally in some meat and dairy products, because they would be too difficult to remove and aren’t considered a major public health threat by themselves.