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

Content provided by the Faculty of the Harvard Medical School

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.

For a vegetable oil spread to stay solid at room temperature, it needs some saturated fat, such as palm or coconut oil, or some partially hydrogenated vegetable oil. If you could be sure that a low-saturated-fat spread made with partially hydrogenated oil had only a minimal amount of trans fat, it might be a good alternative to a spread high in saturated fat but with truly zero trans fat. Unfortunately, you won’t be able to make an informed decision like that until the FDA closes this loophole.

— Caitlin Hosmer, M.S., R.D. Brigham and Women’s Hospital Harvard Heart Letter Editorial Board

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Last updated:	October 01, 2006

Medical content reviewed by the Faculty of the Harvard Medical School. Harvard Health Publications, Copyright © 2007 by President and Fellows of Harvard College. All rights reserved. Used with permission of StayWell.

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