Olive oil may reduce the risk of coronary heart disease, according to research. Now the U.S. Food and Drug Administration has given food companies the green light to advertise olive oil's health benefits on labels of the oil and foods that contain it. Olive oil is good only if it replaces saturated fat and doesn't add to your total calories, the FDA says; specifically, it's the monounsaturated fats in olive oil that are thought to be healthy.

The FDA's decision was based on several studies about olive oil and monounsaturated fat. For example, in one study, healthy young men were put on diets high in saturated fat, high in monounsaturated fat, or high in polyunsaturated fat; after eating the diet high in monounsaturated fat from olive oil, the men had lower cholesterol levels than after eating the diet with lots of saturated fat from butter and cocoa butter.

This makes olive oil the third food to win the FDA's permission to be labelled with health benefits. The other two were omega-3 fatty acids, which come from oily fish, and walnuts. Like olive oil, both can have information on the label about their potential to reduce the risk of coronary heart disease.

Find out more: The FDA's announcements about olive oil, omega-3 fatty acids, and walnuts. Also, read the FDA's letter summarizing the research on olive oil.