Under the proposed regulation, partially hydrogenated oils, a type of trans fat, would be dropped from the agency’s list of safe ingredients — meaning they could no longer be added to foods. The FDA has taken such action only a handful of times — to remove certain artificial sweeteners in the 1970s, and more recently when it prohibited adding caffeine to alcoholic beverages.

WASHINGTON — Heart-damaging trans fat may soon vanish completely from supermarket products such as microwave popcorn, pie crusts, frosting, and biscuit dough after the Food and Drug Administration on Thursday proposed banning the artificially manufactured fat from the food supply .


While many food manufacturers have already removed these oils, including vegetable shortening and margarine, from their products, hundreds of processed foods still contain trans fat in small amounts and dozens contain several grams per serving. The average American eats about 1 gram of trans fat each day compared with 4.6 grams per day in 2003 — before the FDA began requiring food products to list trans fat content on their nutrition labels.

“Current intake remains a significant public health concern,” said FDA Commissioner Dr. Margaret Hamburg. Removing partially hydrogenated oils from food could prevent 20,000 heart attacks and 7,000 deaths from heart disease each year, she added in a conference call with reporters.

Many Americans are unknowingly consuming trans fat in products labeled “zero trans fat” because the current FDA rules are misleading. The agency allows up to 0.5 grams of trans fat per serving in such products. Only those products calling themselves “trans fat free” are required to contain none of the fat. Manufacturers will need to remove all partially hydrogenated oils from their products to comply with the proposed FDA rule.

Trans fat is thought to be particularly harmful to the heart because it raises the amount of “bad” LDL cholesterol in the body while lowering the “good” HDL cholesterol, a combination that heightens the risk of heart disease. Trans fat also increases the level of triglycerides, another fat that in elevated amounts has been linked to type 2 diabetes.


In a review of recent research, the Institute of Medicine, an independent group of scientists that provides advice to the government, determined that artificially produced trans fat provides no known health benefit, and there is no safe level of consumption. Milk and beef naturally contain traces of trans fat, which in such small amounts do not pose much harm.

Many health groups such as the American Medical Association applauded the FDA’s proposed ban. The American Heart Association called it a “tremendous step forward in the fight against heart disease.”

Some consumers, however, may feel otherwise. In a nationwide survey of nearly 1,000 adults conducted over the past week by the Pew Research Center, 44 percent of Americans said they would favor prohibiting restaurants from using trans fat in foods, while 52 percent said they would oppose a trans fat ban in restaurants.

Boston already banned trans fat in restaurants five years ago, and Brookline and Cambridge have also instituted prohibitions, as has New York City. Many large national chains including McDonald’s, Starbucks, and Dunkin’ Donuts have voluntarily removed trans fat from their products — without most consumers noticing a taste difference.

Margarine and vegetable shortenings came into widespread use more than 50 years ago largely because they were cheaper to produce than butter, lard, and other animal shortenings. “They were lower in saturated fat and cholesterol-free, so it was assumed they would be healthier,” said Dr. Walter Willett, chairman of nutrition at the Harvard School of Public Health. “It turned out to be a very bad assumption.”


In 1992, Willett and his colleagues were among the first researchers to find that a high intake of trans fat was linked to elevated cholesterol levels. Through the past two decades, he has coauthored dozens of studies suggesting that people who eat the most trans fat tend to have higher rates of heart disease, type 2 diabetes, and gallstones.

The FDA will decide whether to finalize its determination that trans fat is unsafe after a 60-day comment period on the proposal.

While agency officials wouldn’t speculate on how long it might take to remove trans fat from the food supply, Hamburg said the FDA would be reviewing industry comments on the proposed rule to determine how much time manufacturers will need.

“Six months is probably a reasonable time” to expect the industry to reformulate baked goods, said Michael Jacobson, executive director of the Center for Science in the Public Interest, a nutrition activist group in Washington, D.C. Restaurants can probably switch the oils they use for frying and sauteing in a shorter period of time.

J.M. Smucker Co., maker of Crisco and snack foods that contain trans fat, said in a statement that it has already been working to remove partially hydrogenated oils “out of the very limited number of products” that still contain the ingredient and that it is “confident all product reformulations will be complete well before the FDA implements any new rules.”


While some public health experts have expressed concerns over whether trans fat will be replaced in products with artery-damaging saturated fat, recent research suggests that reformulated products contain a net decrease in saturated fat, said Tufts University nutrition professor Alice Lichtenstein.

“Yes, it will be difficult” for manufacturers to replace trans fat, said Dr. Caroline Apovian, director of the nutrition and weight management center at Boston Medical Center who also worked as a paid nutrition consultant to several restaurant chains to help them remove trans fat from their menus.

“But trans fats are poison, and we’ve known for several years now that they cause heart disease and accelerate artery plaque. The industry had ample time to figure out what to do to eliminate them,” she said.

Deborah Kotz can be reached at dkotz@globe.com. Follow her on Twitter @debkotz2.