Modern food processing has created unnatural kinds of fats called "trans" fats, which are made when unsaturated oils are artificially hydrogenated in order to increase stability and shelf life.

Virtually all packaged foods, including cake mixes, crackers, breakfast cereals, and mayonnaise, are made with artificially hydrogenated fats. Trans fats are also created when unsaturated fats are heated to high temperatures, as in deep-fat frying. Although they are technically unsaturated fats, trans fats behave like saturated fats by clogging arteries and increasing the susceptibility of cholesterol to oxidize. When the American Heart Association advised Americans to give up butter in favor of "heart-healthy" margarine, it was sadly guiding people out of the frying pan right into the fire. The hydrogenated fats in most margarines have now been shown to be far more damaging to the heart and arteries than the naturally saturated fats in butter. Your best bet? Read labels closely. If you see the words "hydrogenated" or "partially hydrogenated," you can be sure the product contains trans fats. From Total Health Breakthroughs.