How do I know if food contains trans fat?

You can figure out if a food contains trans fat by doing a little detective work. On the information label, find the total fat content. Then, subtract the saturated fat and the mono and polyunsaturated fats. This leaves the trans fat. So, for example, if chocolate chip cookies have 12 grams of fat per serving and the label lists 4 grams of saturated fat, the cookies also have 8 grams of artery-aging trans fat.

Another way to tell is to look at the list of ingredients. A food label must list the ingredients in order of quantity, from most to least. If hydrogenated or partially hydrogenated oils are listed early on the list and before polyunsaturated or monounsaturated oils, you know the product contains lots of trans fat. If the label lists unsaturated or monounsaturated oils, olive oil, or canola oil first, the fats are probably okay. Some experts contend that trans fats make up 25 to 60 percent of all fats contained in processed food, and 15 to 30 percent of the total intake of dietary fat. Others disagree, saying the numbers are much lower.

Sometimes the label "trans-fat free" truly means there are no partially or fully hydrogenated oils in the product. Unfortunately, there's a loophole in the labeling laws, so you can't always be sure. The Food and Drug Administration (FDA) labeling law allows food manufacturers to claim their products are trans-fat free as long as an individual serving of the food has less than 0.5 grams of trans fat. There are no requirements for how large the serving size is, and, of course, as soon as you eat more than one serving you may be unknowingly consuming trans fats in significant quantities. Interestingly, the Institute of Medicine has claimed that any amount of trans fat is unsafe.

The only way to be sure that you're not getting any trans fat is to scour the ingredient list on the label for partially or fully hydrogenated oils. Or skip this hassle altogether and eat home-cooked and fresh foods.

"0 grams trans fat!" boasts the label of many margarines, crackers, and other packaged foods. But is it really free of this artery-clogging fat? Turn the package around, and indeed, you'll see a "0 g" after "trans fat" on the nutrition facts panel. But that still doesn't mean the product is truly trans fat-free. Due to a legal loophole in food labeling, a product can state "0 g trans fat" and still contain nearly half a gram (up to 0.49 grams) per serving. Even 1 or 2 grams daily can harm your health, and you can see how quickly a few half grams can add up.

Fortunately, the ingredients list doesn't lie; if it contains any type of partially hydrogenated oil, the product has trans fat. Because you can't tell from the label exactly how much a product may contain, it's best to opt for a brand that contains no partially hydrogenated oil.

And remember, just because a product has no partially hydrogenated oil or trans fat doesn't mean it's healthy. Some manufacturers are simply replacing that type of oil with palm oil, which is high in saturated fat. Or they're using "hydrogenated" or "fully hydrogenated" oil, which does not contain trans fat but, depending on the oil, could be high in saturated fat. So compare labels of similar products and choose those that are not only free of partially hydrogenated oil but also lower in saturated fat (and sodium, while you're at it).