BOSTON -- More than half of all Americans have high cholesterol, and millions rely on medication to keep it in check and reduce the risk of suffering a heart attack.

But Dr. Joseph Keenan, a recently retired professor at the University of Minnesota School of Food Science and Nutrition, said eating certain foods can lower a person's LDL, or bad cholesterol, nearly as much as medication can.

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For more than two decades, Keenan has studied how nutrition and supplements can prevent or reduce the risk of cardiovascular disease. He said plant sterols, sometimes referred to as plant stenols, can be beneficial for patients who want to lower their cholesterol without medication.

Plant sterols are found in every plant, fruit or vegetable.

"They actively block cholesterol from being absorbed in to your body," Keenan said.

That's why scientists were eager to find ways to add sterol supplements to other foods, from milk, cheese and butter to cereal, bread, orange juice and even vitamins.

"You really need to look for a little mark (on the food package) that says 'coro-wise,'" Keenan said.

Keenan's decades of research have shown that eating 800 milligrams of plant sterols each day can lower cholesterol dramatically.

"The LDL, the bad cholesterol, will go down 8 to 15 percent in just two weeks," he said. "And the good news is that translates in to a 30 percent reduction in heart attacks."

Other advice for lowering LDL without medication includes choosing low-fat dairy products, lean meats, and fish that are rich in oils such as salmon, sardines and mackerel.

"They actually help prevent the worst type of heart attack, which is the sudden death heart attack," Keenan said.

He also recommends eating 20 to 25 grams of fiber each day. He said most Americans eat only a fraction of that amount.

"The fiber actually helps take cholesterol out of the body," Keenan said.

When combined with exercise, weight and stress management, the grocery store could become your heart's new best friend.

"You can reduce your risk of heart attack by 70 percent," Keenan said. "Especially if you have a family history. Probably even more so if you have a family history."

Of course, some people will need a prescription to lower their cholesterol, but changing your diet is often an effective first step that can be beneficial without the cost and side effects of prescription medication.

Both Dr. Keenan and the American Heart Association do not recommend that children or pregnant women eat sterol or sterol-supplemented foods.