If you think it's butter, but it's not, it's probably a butter substitute.

While they can be a good alternative, with less fat and calories, Consumer Reports found consumers need to shop carefully.

"You want to avoid butter substitutes that have trans fat, which is more damaging to the heart and body than saturated fat," said Consumer Reports' Erin Gudeux.

Consumer Reports tested 15 butter substitutes for taste, texture and nutrition.

Blue Bonnet  53 percent vegetable oil spread was the lowest rated.

Land O Lakes Spreadable Butter with Canola Oil rated excellent. While it does have less saturated fat because of the canola oil, each tablespoon has 100 calories and 11 grams of fat, the same as butter.

For alternatives with fewer calories and fat, two rated very good: I Can't Believe It's Not Butter Light and Brummel & Brown 35 percent Vegetable Oil Spread made with nonfat yogurt. Each has 45 calories and five grams of fat.

All three that did well in the tests do not contain trans fats.