Harvard Heart Letter

Ask the doctor: Does "no trans fat" really mean no trans fat?

Ask the doctor

Does "no trans fat" really mean no trans fat?

Q. I've been using Take Control in place of butter or margarine because it contains cholesterol-lowering plant sterols. The food label says it contains zero grams of trans fat, even though one of the ingredients is partially hydrogenated soybean oil. Doesn't this mean it contains some trans fat?

A. You get an A+ for savvy label reading. No matter what the label says, a food that contains partially hydrogenated vegetable oil contains some trans fat. How much depends on what kind of oil was used and how much it was hydrogenated. But as long as the food contains less than 0.5 grams of trans fat per serving, the FDA says it can proclaim "no trans fat" on the front and list zero trans fat on the label. (In Canada, the cutoff is 0.2 grams per serving.)

Trans fat boosts levels of LDL (bad) cholesterol as much as saturated fat does. It also lowers HDL (good) cholesterol and increases the tendency for blood clots to form inside blood vessels. None of these is good for your heart. According to the FDA and the Institute of Medicine, we should eat as little trans fat as possible. In practical terms, that means staying below 2 grams a day for someone who takes in 2,000 calories a day. Five servings of "no trans fat" products that each contain 0.4 grams could push you right to that limit.

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