WASHINGTON Neither vitamin C nor vitamin E supplements cuts the risk of cardiovascular disease including heart attack and stroke in a U.S. study published on Sunday.
And a second study failed to show that taking low-dose aspirin helped prevent heart and artery disease among Japanese people with diabetes.
Many people take vitamin supplements to try to ward off chronic disease. In a study aiming to establish whether they prevent heart disease, 14,641 doctors with an average age of 64 took either vitamin C, vitamin E or a placebo for an average of about eight years.
The men who took the vitamins ended up doing no better than those who took a placebo, researchers at Brigham and Women's Hospital in Boston wrote in the Journal of the American Medical Association.
Vitamin E and vitamin C are antioxidants, thought to protect against damage caused by free radicals, substances that can harm cells, tissues and organs. Fruits and vegetables are rich in both, and it is well documented that people who eat plenty of plant foods have a lower risk of heart disease, cancer and other conditions.
"People should continue to focus on eating a healthy diet, exercising regularly and controlling known risk factors such as high cholesterol and high blood pressure to reduce the risk of cardiovascular disease," Dr. Howard Sesso, one of the researchers, said in a statement.
"Unlike most previous studies in which vitamins E and C were given in combination with other antioxidants, this study investigated the two vitamins individually. Our findings add to the growing consensus about vitamin E and C's lack of cardiovascular protection," Dr. J. Michael Gaziano, one of the researchers, added in a statement.
Separately, a study involving 2,539 Japanese men and women with type 2 diabetes found that taking low doses of aspirin daily did not appear to reduce heart disease, stroke or peripheral arterial disease risk.
Heart attack and stroke are leading causes of death in people with type 2 diabetes, which is closely tied to obesity.
But a commentary by an Italian researcher accompanying the study in the Journal of the American Medical Association questioned whether findings involving a Japanese population with a comparatively low risk of cardiovascular disease can apply to people from other places where this disease risk is much higher.
"The use of aspirin for primary prevention of cardiovascular events in individuals with diabetes is widely recommended by existing guidelines, but the evidence supporting its efficacy is surprisingly scarce," Dr. Antonio Nicolucci of Consorzio Mario Negri Sud in Italy wrote.
(Reporting by Will Dunham; Editing by Maggie Fox and Xavier Briand)