There never was any good evidence that using margarine instead of butter cut the chances of having a heart attack or developing heart disease. Margarine may have less saturated fat than butter, but...
www.health.harvard.edu
Then the hazards of margarine came to light. The older margarines had high levels of trans fats that packed a double whammy for heart disease by raising levels of LDL (bad cholesterol) and lowering levels of
HDL (good cholesterol).
The truth is, there never was any good evidence that using margarine instead of butter cut the chances of having a heart attack or developing heart disease. Making the switch was a well-intentioned guess, given that margarine had less saturated fat than butter, but it overlooked the dangers of
trans fats.
Today the butter-versus-margarine issue is really a false one. From the standpoint of heart disease, butter remains on the list of foods to use sparingly mostly because it is high in saturated fat. Margarines, though, aren't so easy to classify. The older stick margarines turned out to be clearly worse for you than butter. Some of the newer margarines that are low in saturated fat, high in unsaturated fat, and free of trans fats are fine as long as you don't use too much (they are still rich in calories).
Healthier alternatives to butter or margarine include olive oil and other vegetable oil–based spreads, which contain beneficial mono- and polyunsaturated fats. Next time you tear into a warm loaf of bread or roll, consider dipping it in olive oil rather than coating it in butter. If you're trying to lower your cholesterol, stanol-based spreads (for example, Benecol and Take Control) are even better, since regular use can help lower LDL cholesterol levels.