David L. Katz, MD
Photo: Mackenzie Stroh
Q: Once and for all, which is better for you—butter or margarine?
— Kerri Oakley, Seattle

A: I recommend margarine, but only if it's the "right" kind. The "wrong" kind is worse than butter. The difference? Margarine is basically a mixture of vegetable oils and was originally marketed as a less expensive and healthier alternative to butter, which is made of animal fat. While both pack around 100 calories per tablespoon and 11 grams of fat ("light" products are less), in butter seven of those grams are saturated; only two are in margarine. The problem is trans fat, which is produced when hydrogen is added to vegetable oil to solidify it and to provide foods with a longer shelf life. Recognized only recently to be just as bad or worse for you than saturated fat, it's in many margarine products. The stick variety contains the most trans fat, and in my opinion, you might as well have butter—at least that's natural; tub margarine has less. Still, you're best off with one of the new spreads designed expressly for health. I like Smart Balance because it's made of heart-friendly oils and has no trans fat. Other spreads (like Benecol and Take Control) are enhanced with plant stanols or sterols, which can lower cholesterol. But you have to eat two tablespoons of Take Control a day (160 calories) and two to three of Benecol (up to 210 calories) to get the benefit, and these products may contain trace amounts of trans fat. Last word: All spreads are fairly concentrated sources of calories, so choose wisely and spread thinly.
As a reminder, always consult your doctor for medical advice and treatment before starting any program.