Which is the better choice?
According to a recent report from the Mayo Clinic, margarine might be the better choice, but beware, not all margarines are created equal.
Margarine is made from vegetable oils, so it contains no cholesterol, whereas butter is made from animal fat, so it contains cholesterol and high levels of saturated fat. Margarine is also higher in "good" fats - polyunsaturated and monounsaturated - than butter is.
But, as with many things in life, it is not as simple as "margarine is better than butter, period." Margarine comes in many different varieties, and the consumer must be aware of the difference when selecting an appropriate margarine. A good place to start is with trans fats. These are the worst fats and should be avoided at all costs.
In general, the more solid the margarine is the more trans fat it contains. Trans fats, like saturated fats, increase blood cholesterol levels and the risk of heart disease. Trans fats also lower high-density lipoprotein (HDL) or "good" cholesterol levels. Tub or liquid margarines are less solid and a better choice than stick margarines.
Taste is also important! Keeping that in mind, look for the margarine with the lowest calories that also tastes good to you, with no trans fat and the lowest amount of saturated fat. You can find this information on the Nutritional Facts panel, most commonly put on the back of the product. It's a good idea to check cholesterol on this panel as well.
And if you already have high cholesterol, check with your doctor about which margarine is right for you!