Many products that advertise zero grams of trans fat on their labels in fact have partially hydrogenated oils in their ingredient lists, and so contain trans fats.

Labeling laws allow a manufacturer to claim ZERO if there is less than .5 grams of an ingredient per serving. That doesn't sound like much, but if a serving size is one teaspoon or one cracker, it can add up to a lot of trans fats in a tub of margarine or a bag of chips. I think the claims are deceptive, but the manufacturers are not breaking the law. Use the list of ingredients as your source of information, not the "zero trans fat" claims. If the words "partially hydrogenated" appear in the list of ingredients, look for another brand.

Polyunsaturated fats in vegetable oils are healthful if they are left in the vegetables. Removing oils from vegetables shortens their shelf life. To preserve their freshness, they are either processed with heat, which destroys the very unstable essential omega-3 fatty acids; or, even worse, they are converted into harmful partially hydrogenated fats. Hydrogen atoms are added to replace the unsaturated double bonds between carbons, to create a very stable, more solid fat that is similar to saturated fat but has a different chemical structure. Approximately 7.5 percent of the fat in our diet comes from partially hydrogenated fats, which have been linked to increased risk for cancer and heart attacks.

Partially hydrogenated fats that you eat are deposited in your body fat. Lenore Kohlmeier of the University of North Carolina biopsied the fat in women's buttocks. She then followed these women for several years and showed that the amount of partially hydrogenated fats in a woman's buttocks predicts her susceptibility to developing breast cancer in the future ( Cancer Epidemiology, October 1997.)

Partially hydrogenated fats increase risk for heart attacks by lowering blood levels of the good HDL cholesterol, raising levels of the bad LDL cholesterol and very bad Lp(a) and increasing risk of clotting. Partially hydrogenated fats lower blood levels of omega-3 fatty acids to create a relative deficiency of these heart-attack-preventing fats.

We have known for more than fifteen years that trans fats increase your risk for heart attacks and possibly some types of cancers such as breast cancer. This summer, Walter Willett, chairman of the Department of Nutrition as Harvard School of Public Health reported that trans fats also increase your risk for getting diabetes (Science News, November 10, 2001.)

Partially hydrogenated fats are the principal fat in many prepared foods, such a french fries, doughnuts, frozen meals, cookies or crackers. The only way to know whether a food contains trans fats is to read the list of ingredients. If you see the words "partially hydrogenated" in front of any vegetable oil, the food contains trans fats, and you have no way to know the exact amount.

Many manufacturers are coming out with new formulations of their popular brands that now contain NO partially hydrogenated oils. Seek out these products and vote with your pocketbook.