Antioxidant supplements: Can they prevent heart disease?

Much research has been done to evaluate the potential role of antioxidant supplements in preventing heart disease. But there is no conclusive evidence to support this possible benefit.

Antioxidants, such as vitamins E and C and beta carotene, are substances found naturally in many foods. They are also available as supplements. Although antioxidants have some health-promoting properties, it isn't clear if antioxidant supplements offer the same benefits as food sources do.

Antioxidants slow oxidation, a natural process that leads to cell and tissue damage. It is believed that oxidation plays a role in the development of fatty deposits in the walls of blood vessels (atherosclerosis), which increases the risk of heart attack and stroke.

Although some early research suggested that taking antioxidant supplements could prevent this process, more recent studies have found no beneficial effect. Some studies even suggest that antioxidant supplements — which contain antioxidants at levels thousands of times higher than those in food sources — have harmful effects. For example, recent analysis of several previous studies of vitamin E suggests that people who take more than 400 international units of vitamin E a day may be at increased risk of death.

For these reasons, the American Heart Association doesn't recommend routine use of antioxidant supplements to prevent or treat cardiovascular disease. Instead, it supports a diet high in food sources of antioxidants and other heart-protecting nutrients, such as fruits, vegetables, whole grains and nuts, to reduce the risk of cardiovascular disease.