David L. Katz, MD
Photo: Mackenzie Stroh
Q: I'm confused. Sometimes a package will say "zero trans fat" while the label lists "partially hydrogenated oil." Can an item have this kind of oil and still have no trans fat?
— Miranda Klement, Gainesville, Texas

A: No. Any product that contains hydrogenated or partially hydrogenated oil has some trans fat. To help explain, let me point to other nutrients: Under FDA rules, a product is allowed to claim zero calories even if it has a few—up to 5 per serving. It can also be sold as fat-free and sugar-free when it actually contains up to .5 grams per serving. Until now companies have gotten away without having to list trans fat on the label. As of this year, however, they are required to post just how much of the artery clogger is in the food—unless there's less than .5 grams per serving, in which case they can say "zero trans fat." The problem is that "one serving" can be misleadingly small (seven or eight "free" cookies could sneak in 3 or more grams of trans fat). If you want my advice, when you see the words partially hydrogenated oil, step away from the box, and nobody will get hurt!