WASHINGTON (CBSNewYork/AP) -- Nutritionists call them one of the worst fats and a leading contributor to heart attacks.
Now, the Food and Drug Administration is taking steps to ban trans fats.
In 2006, New York City issued a first-of-its-kind rule restricting artificial trans fat in restaurants, forcing them to alter recipes so that foods contained no more than 0.5 grams per serving. The change affected customers beyond New York as big chains like McDonald's wound up cutting the fat system-wide.
The ban was one of Mayor Michael Bloomberg's first successful crusades and ended up putting him under fire for trying to run a so-call nanny state.
Dr. Thomas Farley, NYC Health Commissioner, On Trans Fat Ban
"Our prohibition on trans fats was one of many bold public health measures that faced fierce initial criticism, only to gain widespread acceptance and support," Mayor Bloomberg said in a statement. "The groundbreaking public health policies we have adopted here in New York City have become a model for the nation for one reason: they've worked. Today, New Yorkers' life expectancy is far higher than the national average, and we've achieved dramatic reductions in disease, including heart disease. The FDA deserves great credit for taking this step, which will help Americans live longer, healthier lives."
Dr. Thomas Frieden, who was the city health commissioner when the trans fat ban was implemented, currently serves as the director of the Centers for Disease Control and Prevention.
"Trans fats are artificial chemicals that don't need to be in the food supply at all, so we regulated it in a way we could to get them out of restaurants," current New York City Health Commissioner Dr. Thomas Farley told WCBS 880 on Thursday afternoon. "Four grams a day if you eat that much -- that's about as much as would be in one order of french fries -- that increases your risk of heart disease by about 23 percent."
The FDA has determined that trans fats can't be "generally recognized as safe."
It's a tentative determination, but could lead to regulations aimed at eventually phasing out trans fats altogether, CBS 2's Amy Dardashtian reported.
The FDA isn't yet setting a timeline for the phase-out, but it will collect comments for two months before officials determine how long it will take. Different foods may have different timelines, depending on how easy it is to find a substitute.
"We want to do it in a way that doesn't unduly disrupt markets," said Michael Taylor, FDA's deputy commissioner for foods. Still, he said, the food "industry has demonstrated that it is by and large feasible to do."
Trans fats are used both in processed food and in restaurants, often to improve the texture, shelf life or flavor of foods. They are created when hydrogen is added to vegetable oil to make it more solid, which is why they are often called partially hydrogenated oils.
"It's taking normal vegetable oil and adding hydrogen and making the substance thick and waxy and clogs arteries," Dr. Mary Ann McLaughlin of Mount Sinai Hospital told CBS 2's Tony Aiello. "Trans fats are always bad for you."
Partially hydrogenated oil is found in many pre-packaged baked goods, margarine, cake and pancake mixes, fried foods and snack foods.
The trans fats improve flavor and shelf life, but also spike cholesterol levels and are long suspected of contributing to heart disease – one of America's leading causes of death.
"There's absolutely no redeeming value to trans fats and there's every reason in the world to get them off our shelves," said Dr. Pamela Peeke of the University of Maryland. "Trans fats have a direct association with cardiovascular disease as well as cancer, they actually increase inflammation throughout the body which we have seen as a precursor for many disease entities."
However, some who use trans fats said the government should stay out of the kitchen.
"It does feel nice to the palate in your mouth," Thomas Gencarelli of Brothers Quality Bakery in Kearny, N.J. told Aiello. "The difference is I think that it does give you a cleaner taste."
Gencarelli said he doesn't believe the trace amounts of trans fat in his donuts are a health risk.
"We're not killing anyone. I think that the customer should decide whether they want something like that," he told Aiello.
With the feds cooking up a trans fat ban, Brothers Quality Bakery has some experimenting to do when it's time to make the donuts.
Suppliers will no longer be able to sell trans fatty oils, so the bakery needs a substitute.
"We'll experiment and we'll go back and forth to see what works the best for us," Gencarelli said.
FDA Commissioner Margaret Hamburg said the move could prevent 20,000 heart attacks and 7,000 deaths each year.
Many companies have already phased out trans fats, prompted by new nutrition labels introduced by FDA in 2006 that list trans fats and by an increasing number of local laws that have banned them.
When Dunkin' Donuts decided to phase out trans fats, it tested dozens of options before settling on a trans fat-free blend of palm, soy and cottonseed oils, Aiello reported.
Though they have been removed from many items, the fats are still found in processed foods, including in some microwave popcorns and frozen pizzas, refrigerated doughs, cookies and ready-to-use frostings. They are also sometimes used by restaurants that use the fats for frying. Many larger chains have phased them out, but smaller restaurants may still get food containing trans fats from suppliers.
As a result of the local and federal efforts, consumers have slowly eaten fewer of the fats. According to the FDA, trans fat intake among American consumers declined from 4.6 grams per day in 2003 to around one gram per day in 2012.
FDA officials said they have been working on trans fat issues for around 15 years — the first goal was to label them — and have been collecting data to justify a possible phase-out since just after President Barack Obama came into office in 2009.
Samantha Cassety, the Nutrition Director for Good Housekeeping magazine, told CBS 2's Dave Carlin that until a nationwide ban is in place shoppers can look at two different spots on the food label to see if a product contains trans fats.
"You want to make sure it says zero grams trans fat. But, that could still mean the product might have up to .4 grams so you want to look in the ingredient list for the words partially hydrogenated vegetable oil and if you don't see them you know you are in the clear," she said.
The U.S. isn't the only country taking on trans fat. The World Health Organization said five others, including Brazil, the Netherlands and South Korea, are trying to reduce it.
The health benefits could be huge. The CDC said avoiding trans fat foods could prevent between 10,000 and 20,000 heart attacks a year in the U.S.
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