The spread that you add to your toast every morning may do more than just satisfy your taste buds. If you are using a specially formulated margarine you're probably doing your heart a favor as well. Cholesterol-lowering margarine hit most grocery store shelves in the United States in 1999. These margarines are fortified with unique, natural substances called plant stanols or sterols. The substances are found in most vegetables, fruits, nuts and vegetable oils and are lauded as ideal cholesterol-lowering agents, said Dr. Nilo Cater, assistant professor of internal medicine and nutrition scholar in the Center for Human Nutrition. They are easy to consume, and you can't tell a difference in taste, Dr. Cater said.

When incorporated with therapeutic lifestyle changes which include a diet low in saturated fats and cholesterol, weight reduction and increased physical activity a 20 to 25 point reduction in the low-density lipoprotein cholesterol, the so-called bad cholesterol, is achieved.

And that's not the half of it, Dr. Cater said. When people who require drug therapy incorporate these margarines into their diets daily, they get an additional 10 percent to 15 percent reduction in LDL. That usually means a 20 to 25 milligram per deciliter drop in LDL cholesterol levels. There's no question that certain people need to be on cholesterol-lowering medications, but this is a very effective way for people who are on drug therapy to achieve their optimal LDL cholesterol levels without going up to a higher dose of drugs. The average person consumes about 300 milligrams of plant stanols and sterols daily. To get the cholesterol-lowering effects from these natural substances a person would have to consume 2,000 to 3,000 mg daily.

Even though we eat foods that contain plant stanols and sterols, we don't eat enough. Vegetarians don't even eat enough to get this effect, he said. The two cholesterol-lowering margarines available at most grocery stores are Benecol and Take Control. Although these margarines are not a prescription medication, Dr. Cater said that people should adhere to the recommended serving sizes as they would a prescribed medication.

It's not a drug, but you have to sort of take it like a drug to get the full effect, Cater said. I think people need to understand that you need to take it consistently like you would one of your prescription medications. One serving, or one tablespoon, of these margarines contains 1,000 mg of either plant stanols (found in Benecol) or plant sterols (found in Take Control). Dr. Cater says two servings, or two tablespoons, daily are recommended to achieve a cholesterol-lowering effect. Plant stanols and sterols lower LDL cholesterol levels by interfering with cholesterol absorption.

That's the whole concept behind the products, he said. They interfere with cholesterol absorption in the gut. The molecular structures of the plant stanols and sterols are very similar to cholesterol. Because they look so much like cholesterol, when they are present in high amounts they can disrupt the process by which cholesterol is absorbed. The result is that the liver receives less cholesterol from the gut and that stimulates the liver to take up more cholesterol from the blood.

The plant stanols and sterols decrease absorption not only of cholesterol from the diet, but also the cholesterol that the body makes; therefore, people who are already on a low-cholesterol diet can still see a significant drop in LDL cholesterol because the bulk of the cholesterol in the gut is cholesterol that the body makes.

Researchers have known since the 1950s that if consumed in very high amounts, these substances had the ability to drastically decrease blood cholesterol levels. These substances were available in different forms in the past, Dr. Cater said. They were included in capsules, powers and liquid suspensions. But the effect of lowering cholesterol was not always consistent.

Previous research conducted by Dr. Scott Grundy and his colleagues incorporated plant stanols and sterols into fat-based foods to determine an efficient way to transport these substances into the small intestine, where cholesterol absorption takes place.

This pioneering research led to a discovery by Finnish researchers, who in the early 1990s developed a process called esterification, which makes the plant stanols soluble in fat-based foods such as mayonnaise and margarines. Since that time, some three dozen studies have been published that have found that in these food forms, plants stanols and sterols consistently and very effectively lower blood cholesterol levels, Dr. Cater said. Currently, only specially formulated margarines are available in the United States. But in Europe, stanols are incorporated into yogurt, cream-cheese spreads and margarines.

And the cost?

Dr. Cater has a simple way to figure. In the vending machines in our clinic, the price for a can of soda has gone up to about 65 cents. So I always tell patients that you just spent more money on a can of diet soda than you would to get the daily recommended dosage of these cholesterol-lowering margarines.