Butter vs. margarine: What's better for you in baking

If there's one indulgence that's practically unavoidable this time of year, it may well be the tray of holiday cookies. Adorned with sprinkles, spread with jam and frosting or dusted with powdered sugar, such cookies are a far cry from a healthful snack. Still, many cooks may nonetheless stand in their kitchens and wonder: Is it better to make them with margarine or butter?

Butter and margarine have a similar overall fat content -- and therefore a lot of calories, says Katherine Zeratsky, a registered dietitian with the Mayo Clinic in Rochester, Minn. But the composition of the fats in butter and margarine differs significantly.

"You have to pick the lesser of two evils," Zeratsky says. "In butter, it's the saturated fat content, and in margarine, it's trans fat."

A tablespoon of butter contains more than three times the amount of cholesterol-raising saturated fat than the same amount of margarine -- 7 grams in butter compared with 2 grams in margarine.

In addition, butter and margarine contain mono- and polyunsaturated fats, but margarine contains them in far greater amounts: close to 9 grams per tablespoon compared with butter's 3.5 grams. These fats don't raise LDL cholesterol -- and some can help lower it, says Penny Kris-Etherton, professor of nutrition at Penn State University in University Park, Penn.

Margarine's drawback is its trans-fat content. Margarines are made from blends of vegetable oils, such as corn, soybean, safflower or canola. Hydrogenation, a chemical process, replaces double chemical bonds in those oils with single chemical bonds, making the liquid oils solid at room temperature. When that replacement process is incomplete, the result is a partially hydrogenated oil, also known as a trans fat. Trans fats are what make margarine solid instead of liquid -- but they've also been shown to be even worse for heart health than saturated fats. Not only do trans fats raise LDL cholesterol levels, they also lower HDL, or good, cholesterol.

For the last two years, manufacturers have been forced to list trans fats on food labels; as a result, many have reformulated their margarines (and other products) to lower or eliminate their trans fat content.

But the letter of the law is such that a food can claim to have no trans fat as long as it contains less than 0.5 gram of trans fat per serving. "Even when the label says trans fat-free, it doesn't really mean that," says Barry Swanson, a food science professor at Washington State University in Pullman.