Researchers in the U.S. say middle-aged women at risk for heart disease derive little benefit from taking vitamins C, E or beta carotene.
The researchers say eating a diet rich in those vitamins does benefit the heart.
A new study by researchers at Brigham and Women's Hospital and Harvard Medical School in Boston says vitamin supplements may not reflect the complex vitamins and nutrients found in foods, which possibly explains the discrepancies between most intervention trials and studies of fruits and vegetables.
Experts say a nutritious diet rich in the vitamins which protect the body's cardiovascular system counteract compounds known as "free radicals" which are harmful as they build up in the body and can damage artery linings, encourage blood clots and alter the function of blood vessels.
Study author Nancy Cook says though additional research into combinations of agents, particularly for stroke, may be of interest, widespread use of these individual agents for cardiovascular protection does not appear to be warranted.
Cook's study involved 8,171 women with an average age of 60.6, who were monitored for roughly nine years for fatal heart disease, heart attacks, strokes and heart-related surgery.
The women, who either had a history of cardiovascular disease or three or more risk factors, were randomly assigned to take 500 milligrams of ascorbic acid (vitamin C) or placebo every day; 600 international units of vitamin E or placebo every other day; and 50 milligrams of beta carotene or placebo every other day.