Which is healthier? Margarine or butter? Liquid margarine is a healthier option, but if truth be told, neither is good for you.

Butter contains saturated fat, while nearly all margarines contain some saturated fat and trans fatty acids. Recent studies on the potential cholesterol-raising effects of trans fatty acids have raised public concern about the use of margarine. On the other hand, butter is unhealthy because it is made from animal fat and contains cholesterol and high levels of saturated fat.

Since most margarines are made from vegetable oils, they contain no cholesterol, says the Mayo Clinic's Martha Grogan, M.D., a consultant in the Division of Cardiovascular Diseases and assistant professor of medicine at Mayo Medical School. "Margarine is higher in 'good' fats, which are polyunsaturated and monounsaturated, than butter is," she adds. "These types of fat help reduce low-density lipoprotein (LDL), or 'bad,' cholesterol, when substituted for saturated fat."

Still, not all margarines are created equal. "Some may even be worse than butter," warns Grogan.

Indeed, margarines are processed using a method called hydrogenation, which results in unhealthy trans fats. In general, the more solid the margarine, the more trans fatty acids it contains. In other words, stick margarines usually have more trans fats than do tub margarines, which are softer. Like saturated fats, trans fats increase blood cholesterol and the risk of heart disease. In addition, trans fats can lower high-density lipoprotein (HDL), or "good," cholesterol levels.

The American Heart Association recommends using soft margarines (liquid or tub varieties) over harder stick forms. Look for ones that have "zero grams of trans fat" on the Nutrition Facts label. The more liquid the margarine, the less hydrogenated it is and the less trans fatty acids it contains.

Butter is unhealthy because it is rich in both saturated fat and cholesterol. It is potentially a highly atherogenic food, too, which means it is a food that causes the arteries to be blocked.

When selecting a margarine, look for ones with liquid vegetable oil as the first ingredient. Even better, choose "light" margarines that list water as the first ingredient, because these are even lower in saturated fat, advises the American Heart Association. Look for margarines that have the lowest trans fat content possible and less than two grams total of saturated plus trans fats. Manufacturers are required to list saturated and trans fats separately on food labels. Margarines fortified with plant sterols (made from soybean and pine tree oils) can help reduce LDL cholesterol levels by more than 10%. The amount of daily plant sterols needed for results is at least two grams. The American Heart Association recommends foods fortified with plant sterols for people with levels of LDL cholesterol over 160 milligrams per deciliter (4.1 mmol/L).

If you don't like the taste of margarine and don't want to give up butter completely, consider using whipped butter or light or reduced-calorie butter, advises Grogan. There are also spreadable butters with vegetable oils added. Per serving, these products have less fat and calories than regular butter. The important thing is to use these products in small amounts - just enough to add flavor to the foods you're eating, she adds.