Phantom fat is hiding in your cereal bowl. It's the bad boy in your bag of microwave popcorn. It lurks in those low-fat cookies and even in that energy bar.
The stuff is called trans fat, created when ordinary vegetable oil is processed into partially hydrogenated oil. It's why Crisco stays solid at room temperature and what makes cakes moist, cookies fresh and crackers crisp. Partially hydrogenated oil is in about 40 percent of the food at the grocery store, including some products most consumers regard as healthy.
A generation ago, when cardiologists waved Americans off saturated fats like butter and beef tallow, partially hydrogenated oils became a preferred alternative. Now, in an about-face, researchers have determined that trans fat can grease the way to a heart attack faster than a cup of lard.
Some of the nation's leading medical researchers also believe that the trans fat that marbles the modern American diet may be why kids are so fat, diabetes is at record levels and why some people develop cancer. They say trans fat is a big player in Syndrome X, a cluster of health problems characterized by a beer belly, high blood pressure and out-of-whack blood fats and sugars.
"There should be a warning on food made with this stuff like there is on nicotine products. It's that bad for you," says Dr. Jeffrey Aron, a University of California at San Francisco professor of medicine and one of the nation's leading experts on fatty acids and their effects on the body.
But there is no warning label. Trans fat amounts aren't regulated at all, so manufacturers and fast food operators don't have to list it on nutrition labels. That means there's no easy way to know how much you're eating.
And chances are, it's a lot more than you think.
Virtually every fast-food or family restaurant french fry is cooked in trans fat-filled grease. Almost half of all cereals, both cold and hot, contain it, according to the Food and Drug Administration. So do 70 percent of cake mixes, 75 percent of chips and other salty snacks, 80 percent of frozen breakfast foods like waffles, and 95 percent of cookies.
Even products people buy when they want to eat healthier - granola, power bars and low-fat cookies and crackers - are made with partially hydrogenated vegetable oil. During a recent informal survey of 140 varieties of crackers on a typical supermarket shelf, only three brands had no partially hydrogenated oil.
Because trans fat flies under the radar, food labeled "low in saturated fat," "cholesterol-free" or "made with 100 percent vegetable oil" can have so much trans fat that consumers focused on heart-healthy food wouldn't touch many of these products - if they knew.
The FDA, which could decide by September whether to require trans fat on food labels, estimates that listing it could prevent as many as 5,600 heart disease deaths a year - not only because people would be able to choose healthier foods but also because manufacturers would choose to reduce the amount of trans fat rather than put it on the label.
"The labels on food say how much fat but not what kinds of fat," Aron explains. "It's insidious and we're nowhere near the level of awareness we need to be."
How much bad fat do you really eat?
On the standard American food label, trans fat content is invisible. Only three types of fat - unhealthy saturated fat and, in cases when certain health claims are made, poly- and monounsaturated fats - must be listed under the total fat content.
But there are some tricks to figuring out if food has trans fat.
- Figure out how much fat you need every day. For an average healthy person who eats 2,500 calories a day, about 30 percent or less should come from fat. That translates to about 80 grams a day. And of that, only about 25 grams should be saturated or trans fat.
- Look for the words hydrogenated, partially hydrogenated or fractionated in the list of ingredients. Trans fat comes from hydrogenation. The higher up partially hydrogenated oil is on the list of ingredients, the more trans fat the product has.
- Note the amount of total fat listed and compare it to the breakdown of specific fats on the label. The results may surprise you. A box of reduced-fat Triscuits, for example, has 3 grams of fat per 7-cracker serving. Saturated fats make up 1/2 gram and monounsaturated fats 1 gram. The crackers have no polyunsaturated fats, so the remaining 1 1/2 grams must be the only other kind of dietary fat - trans fat.
One study, by the Center for Science in the Public Interest, showed that foods with partially hydrogenated oils in the ingredient list contained 1 gram of hidden trans fat for each gram of saturated fat. That means that Chips Ahoy cookies, for example, with 2 grams of saturated fat per serving also contain 2 additional grams of trans fat.
Know your fats
There are only four kinds of fats in our diet - monounsaturated, polyunsaturated, saturated and trans.
- Mono- and polyunsaturated fats. These are considered "good" fats. They do not clog arteries and, in moderation, can contribute to a healthy diet. They include olive, canola, peanut and walnut oils.
- Saturated fat. This is mainly animal fat, the kind found in beef, butter, lard, the skin of chicken, whole milk, whipped cream, egg yolks and other products that come from animals. Coconut and palm oils are also saturated. Too much raises the level of artery-clogging cholesterol.
- Trans fat (trans-fatty acids). These are formed when oil is hydrogenated. Some naturally occurring trans fats can be found in small amounts in animal products. Like saturated fat, trans fat raises the level of harmful blood cholesterol (LDL) as well as the ratio of LDL to the more beneficial HDL cholesterol. Some researchers believe it changes how cells process insulin - which can lead to diabetes - and they have linked it to cancer. Trans fat is found in many processed, convenience and fast foods - French fries, fried chicken, doughnuts, pastries, cookies, crackers and some breakfast cereals.
- Partially hydrogenated oil. This manufacturing process creates trans fat. A hydrogen atom is mixed with non-saturated liquid oil from plants like corn or soy to make fat such as shortening and margarine that stay solid at room temperature.
- Fractionated oil. This type of oil is created by a manufacturing process that uses high temperatures or solvents to separate hydrogenated oil into liquid and solid parts. When listed on food labels, it indicates the presence of trans fat.