Q&A: What is "interesterified fat"?

A package of crackers I recently bought lists "interesterified fat" as one of the ingredients. What is that, and is it harmful? —A.G., Bedford Hills, N.Y.

Some manufacturers now use interesterified fat instead of partially hydrogenated vegetable oil, the source of the heart-harming trans fats now being removed from many foods. It's created by chemically inserting saturated fatty acids, which come mainly from animals, into the molecular backbone of vegetable oil to make it more stable. But some research suggests that the new fats are just as bad for you as trans fats. They might increase heart-disease risk by lowering HDL (good) cholesterol and raising LDL (bad) cholesterol, as trans fats do. And they might increase the risk of type 2 diabetes by raising fasting blood-glucose levels and decreasing insulin response. You can avoid trans fats by checking nutrition labels on packaged foods or look at the ingredient line for partially hydrogenated vegetable oils, but to find interesterified fats you have to read the ingredients list.

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