Sufficient blood levels of carotenoids, a family of antioxidants in fruits and vegetables, might reduce the risk of ischemic stroke, according to a study published today in the rapid access issue of Stroke: Journal of the American Heart Association
An ischemic stroke is caused by a blood clot and is the most common type of stroke.
Fruit and vegetable intake has long been associated with a lower risk of ischemic stroke, said study author Jing Ma, M.D., Ph.D., assistant professor of medicine, Brigham and Women’s Hospital, Harvard Medical School, Boston. Researchers investigated which antioxidants in fruits and vegetables might have this positive effect.
The Physicians’ Health Study involved 22,071 U.S. male physicians, 68 percent of whom provided blood samples at the start of the study in 1982. Among the 15,000 who didn’t have cardiovascular disease at the beginning of the study, 297 had an ischemic stroke during the study’s 13-year follow-up.
Analyzing blood samples among stroke patients, researchers measured levels of antioxidants, including carotenoids (vitamin A family, including alpha-carotene, beta-carotene, lycopene, lutein and beta-cryptoxanthin) and tocopherols (vitamin E). They then compared their findings to the blood levels of an equal number of men who did not have stroke.
They found that men who were in the lowest 20 percent quintile (bottom fifth) for carotenoid levels of alpha-carotene, beta-carotene and lycopene had the highest risk of ischemic stroke.
Men who were above the second through fifth quintiles were at a 40 percent lower risk of developing ischemic stroke during the 13 years than men in the lowest quintile, Ma said.
Once blood levels moved beyond that 20 percent threshold of carotene, the stroke protection benefit did not seem to increase with higher levels, Ma said.
The carotenoid level could have been the result of these men eating fruits and vegetables or taking antioxidant supplements.
The observational study shows an association between fruit and vegetable intake and stroke risk, but did not prove that eating fruits and vegetables caused the lower risk.
The results of this study support a diet high in fruits and vegetables to reduce ischemic stroke risk, she said.
The American Heart Association recommends a total well-balanced nutritious diet consisting of a variety of foods: fruits, vegetables, whole grain cereals and bread, nonfat and low-fat dairy products, lean meat, fish and poultry, and the use of monounsaturated and polyunsaturated fats for saturated fat.
Co-authors are A. Elizabeth Hak, M.D., Ph.D.; Calpurnyia B. Powell, B.S.; Hannia Campos, Ph.D.; J. Michael Gaziano, M.D.; Walter Willett, M.D., Dr.P.H.; and Meir J. Stampfer, M.D., Dr.P.H.