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The FDA has taken the first step toward eliminating the use of partially hydrogenated oils -- the main dietary source of artificial trans fat -- in processed foods, the agency announced in a notice scheduled for publication in the Federal Register on Friday.

On the basis of a review of scientific evidence and findings from expert panels, the agency made a preliminary determination that the oils "are not generally recognized as safe for use in food" and should be eliminated, FDA Commissioner Margaret Hamburg, MD, said on a conference call with reporters.

The decision "is very welcome and strongly supported by massive scientific evidence that trans fat has many adverse effects on health," Walter Willett, MD, DrPH, of the Harvard School of Public Health, said in an email to MedPage Today. "Trans fat has no place on the table, and this step will help make the diets of Americans safer."

Even in the absence of an outright ban, consumption of trans fat has been declining in recent years because of voluntary efforts on the part of the food industry to remove it from products, less use of trans fat by restaurants (spurred by local bans), and increased awareness among consumers about the negative health effects, which include increased LDL cholesterol levels and risk of coronary heart disease.

According to the FDA, trans fat consumption declined from about 4.6 grams per day in 2003 to about 1 gram a day in 2012.

Nevertheless, many products still contain trans fat -- such as certain desserts, microwave popcorn, and frozen pizza -- and consumption "remains a public health concern," Hamburg said, noting that the Institute of Medicine has concluded that there is no safe level of trans fat consumption and that intake should be as low as possible.

Citing the CDC, she said that "removing partially hydrogenated oils from processed foods could prevent as many as 20,000 additional heart attacks and up to 7,000 additional coronary deaths each year. These are significant numbers."

Willett added, "Further removal of trans fats will also likely nudge down rates of diabetes, obesity, and other conditions as well."

"Importantly, by getting trans fat off the table entirely, we will be able to focus attention on other aspects of diet that also need to be improved," he said. "This will likely have a ripple effect worldwide because other countries are considering similar actions."

The FDA’s decision is an appropriate one, but the additional public health impact of removing trans fat after substantial reductions in intake have already occurred is unclear, Robert Eckel, MD, of the University of Colorado at Denver, told MedPage Today.

"Getting trans fat out of foods is a smart decision,” Eckel said in an interview. "It's just that the impact now of ingesting less than 1 gram a day versus 4-and-a-half a decade ago is less likely to have clinical benefit."

Banning trans fat could have effects on clinical practice, as well, David Frid, MD, of the Cleveland Clinic, said in an interview with MedPage Today.

"Physicians will hopefully see some better improvement in controlling cholesterol on top of what we already can do with medications," Frid said. A ban "also may impact people's weight and ... it'll be something that physicians can reinforce from a dietary perspective why a lot of the current foods that people are eating that are bad and add to obesity should be eliminated from people's diets."

Before the FDA issues a final determination, however, the public and industry will have the opportunity to provide comments for 60 days both about the need to remove trans fat from foods and about how long food manufacturers would need to remove trans fat from various types of products.

"If we finalize our preliminary determination, partially hydrogenated oils will be considered food additives and could not be used in food unless authorized by regulation based on a demonstration of safety," Michael Taylor, JD, FDA's deputy commissioner for foods and veterinary medicine, said on the call.

Such an action would not apply to naturally occurring trans fat found in some meat and dairy products.

The Center for Science in the Public Interest (CSPI) -- which petitioned the FDA to ban the use of partially hydrogenated oils in 2004 -- hailed the announcement as a "historic development in [the] fight against heart disease."

"Getting rid of artificial trans fat is one of the most important life-saving measures the FDA could take," CSPI's executive director Michael Jacobson said in a statement. "Thousands of heart attack deaths will be prevented in the years ahead. The FDA deserves credit for letting science, and not politics, shape its new proposed policy on artificial trans fat."