You think you're eating a healthful diet because you've limited your consumption of artery-clogging saturated fat. But if you are not minding your intake of another harmful fat called trans-fat, you might still be increasing your risk of heart disease. Indeed, whereas saturated fat raises the body's level of bad "LDL" cholesterol, trans-fat packs a double whammy by also reducing the good "HDL" cholesterol that protects against heart disease, according to Penny Kris-Etherton, professor of nutrition at Pennsylvania State University.
Many nutritionists say the most effective way to reduce this risk is by limiting the two "bad" fats combined to 10% or less of your daily calories. For a 2,000-calorie diet, that's less than 20 grams of saturated and trans-fat. Trouble is, while food labels are required to break out the saturated fat content, most are silent when it comes to trans-fat. And they can keep mum until Jan. 1, 2006, when a new Food & Drug Administration disclosure requirement kicks in.
In the meantime, if you want to avoid trans-fat, you can purge your pantry of the known offenders. To identify the less obvious ones, you'll need to do a bit of nutritional sleuthing.
Trace amounts of trans-fat occur in beef, cheese, butter, and milk. But the real culprits are commercially prepared fried and baked goods, such as french fries, chicken nuggets, doughnuts, cookies, crackers, and pies. Margarine is another big source, although it's lower in saturated fat than butter. Trans-fat can also pop up in unexpected places, such as in foods that are relatively low in fat. An example: Kellogg (K ) Nutri-Grain's mixed berry cereal bars, which contain 0.6 grams of trans-fat.
LONGER SHELF LIFE. To detect trans-fat, start with the fine print on the label. If you see partially hydrogenated or hydrogenated oil in the ingredients, it's a good bet the product contains trans-fat, says Eric Rimm, associate professor of epidemiology and nutrition at Harvard School of Public Health. Trans-fat is made when manufacturers add hydrogen to vegetable oil. This enhances flakiness and shelf life, while also making foods cheaper to produce, says Margo Wootan, director of nutrition policy at Washington's nonprofit Center for Science in the Public Interest.
Exactly how much trans-fat a food contains is impossible to determine. To get a rough idea, look at the order of ingredients. The closer hydrogenated oil is to the top, the more trans-fat is likely present, Rimm says.
You can obtain a more precise reading if a label goes beyond what's required and breaks down total fat into several components. For example, look at Pepperidge Farm's (CPB ) pizza-flavored goldfish crackers. Eat one serving, or 55 tiny crackers, and you'll consume 7 grams of total fat. That includes 1.5 grams of saturated fat and 3.5 grams of the more benign polyunsaturated and monounsaturated fats. Total that up, and you get 5 grams -- or 2 grams shy of the 7 listed under "total fat." What happened to the remaining 2 grams? Since the product contains partially hydrogenated vegetable shortening, trans-fat is a suspect.
ROUNDING TO ZERO. Such reckoning is far from perfect. The government allows food companies to round fat content to the nearest half gram. Foods with less than 0.5 grams of fat can round down to zero. So rounding may account for some of the goldfish crackers' missing 2 grams of fat. A spokesperson for Pepperidge Farm puts the trans-fat content at between 1 gram and 1.5 grams per serving. The company is evaluating ways to reduce or eliminate trans-fat.
Still, until companies remove trans-fat or give it a place on the label in 2006, such approximations are the best you can do.
By Anne Tergesen