Updated November 25, 2014.
Butter vs margarine - which one should you eat on a low cholesterol diet?
Margarine and butter are popular spreads and widely used cooking ingredients. Margarine and butter are processed a little differently, and you may be able to detect differences in consistency and taste as a result. However, when it comes to lowering your cholesterol, which one should you use?

The Winner: Margarine

Margarine comes in a variety of forms: Stick, spread, and liquid.

It does not contain as much saturated fat as butter does. It does, however, contain unsaturated fats, which have been linked to lowering cholesterol and are also found in foods such as nuts and fish.

However, these unsaturated fats undergo a process referred to as hydrogenation, which introduces harmful trans fats into the margarine. The trans-fatty acids are what gives margarine its solid consistency at room temperature. But they have also been linked to causing heart disease.

Generally, you can determine how much trans-fats each form of margarine has by its softness. For example, those that are more solid at room temperature contain more trans-fats than those that come in a tub, which are generally softer. Since there are many brands of margarine out there, look for liquid options that do not contain trans-fatty acids or “partially hydrogenated” oils in their ingredients. Check your food labels if you are ever in doubt.

The Loser: Butter

Butter comes in two major forms: Stick and spread.

It is primarily made up of saturated fat and cholesterol. It doesn’t sound like much, but if you look at the ingredients label on the back of a butter product, one tablespoon contains almost the maximum amount of saturated fat and cholesterol allowed each day.

One tablespoon of butter contains roughly 30 mg of cholesterol and 7 g of saturated fat -- the maximum amount allowed daily is 200 mg and 10 mg, respectively. Additionally, because both of these types of fats have been linked to raising cholesterol and risk of heart disease, butter generally is not recommended.

If you are looking for a suitable margarine or butter product to keep your heart healthy, margarine is usually recommended. Be sure to look for softer margarines that do not contain trans fats and partially hydrogenated oils. An even better choice would be spreads that contain phytosterols, such as Benecol, which can lower your LDL (“bad” cholesterol) by 10 percent.

_{Sources:
Rolfes SR, Whitney E. Understanding Nutrition, 3rd ed 2005.}