Doughnuts, french fries, crackers and fried chicken are just some of the tasty foods that include trans fat. But it's at least as dangerous to the heart as saturated fat — and many doctors consider it worse.
Thirteen million Americans have heart disease and trans fat contributes to the problem.
"We know [trans fatty acids] contribute to an increase in LDL, which is the bad cholesterol, and, therefore, it causes heart disease," Health and Human Services Secretary Tommy Thompson said Wednesday on CBS News' Early Show.
Food and Drug Administration regulations to be unveiled Wednesday will require nutrition labels to include a new line listing the amount of trans fat in each food right under the amount of saturated fat, say consumer advocates and industry representatives familiar with the FDA's decision.
Add the two lines together to learn the total of heart-risky fats in every serving.
"We're trying to make the consumer a lot smarter when they go and purchase foods to make sure that they look at the label and find foods that will not contribute to heart disease," said Thompson
Food companies have begun reducing the amount of trans fat in foods and "the lower amount is just that much better," he added.
"We're also hoping that companies are going start competing," he told co-anchor Julie Chen. "We know that that usually happens in the marketplace. They will find ways in which they can reduce the transfatty acids or eliminate them and, therefore, make foods a lot healthier."
"It's a good first step," said Margo Wootan of the Center for Science in the Public Interest, which petitioned the FDA 10 years ago to make the change. "People will be able to compare different products and determine which ones are worse for their hearts."
Wootan said the comparisons won't be easy: The labels won't tell consumers how much a candy bar or doughnut counts against their daily allotment of total unhealthy fat. Nor will they bear a message the FDA debated this spring — that trans fat consumption should be as low as possible.
In recent weeks, FDA Commissioner Mark McClellan has promised the change, first proposed in 1999. Agency officials wouldn't comment Tuesday.
The FDA has estimated that merely revealing trans fat content on labels would save between 2,000 and 5,600 lives a year, as people either chose healthier foods or manufacturers changed their recipes to leave out the damaging ingredient.
Food companies already are preparing. Frito-Lay has announced it is eliminating trans fat from its popular Doritos, Tostitos and Cheetos, and became the first major manufacturer to voluntarily begin adding trans fat content to the labels of other brands earlier this year.
Although the FDA will allow companies to phase in the switch, consumers will see many revealing trans fat content within just a few months, said Tim Willard of the National Food Processors Association.
"Clearly this is going to be a major change to food labels, and it's going to help consumers who are seeking information about trans fat content of foods to find it," he said.
Saturated fat is found primarily in meat and other products containing animal fat. People are advised to eat no more than 20 grams a day, about 10 percent of calories.
Some surveys suggest trans fat comprises up to another 10 percent. Both types can increase the risk of heart disease, although some research suggests trans fat may be the worst culprit.
Trans fat is in numerous products, from meats and dairy products to pastries. The most common source is partially hydrogenated vegetable oil, where liquid oil is turned into a solid to protect against spoiling and maintain long-term flavor.
High-fat foods have long been a staple of the French diet, which has received attention lately because while the French are known for a diet rich in cheese, butter, cream and wines, the French live longer and have less heart disease than Americans.
Neurophysiologist Dr. Will Clower is the author of "The Fat Fallacy: Applying The French Diet to the American Lifestyle. Dr. Clower told CBS News Correspondent Melissa McDermott the key is moderation and no between-meal snacks.
"You don't have to give up your fats," Clower said. "You don't have to give up your carbohydrates. What you have to do is change your relationship with your food."
Typically, the harder a margarine or cooking fat, the more trans fat it includes. Soft, spreadable margarine in tubs, for instance, contains little if any trans fat, while stick margarine can contain a lot. In other foods, the only way consumers could tell which contained trans fat was to check the ingredient list for the word "hydrogenated."
The National Academy of Sciences, which sets nutrition levels, last year ruled that while eating some trans fat may be unavoidable, there is no safe level that it could set as an upper limit. So while product labels today list what percent of total calories a food offers in saturated fat, the new trans fat labels will won't.
The FDA had considered putting a footnote on labels recommending eating only a little trans fat, but consumer testing found that had the unintended consequence of scaring people back to foods high in saturated fat, said Stephanie Childs of the Grocery Manufacturers of America, which lobbied against the move.
For now, the FDA plans to do more research on how to educate consumers about heart-damaging fats so that they make better food choices, Childs said.