THURSDAY, June 3, 2004 (HealthDayNews) -- Higher blood levels of carotenoids, antioxidants found in fruits and vegetables, might reduce the risk of stroke, a study finds.
The risk of ischemic stroke, the most common kind that happens when a clot blocks a brain artery, was 40 percent lower in men with the highest blood levels of carotenoids than in those with the lowest levels, said a report in the June 4 issue of Stroke.
The report came from the Physicians' Health Study, which has followed more than 22,000 male doctors since 1982. It covers a 13-year period, in which 297 of them had ischemic strokes.
The researchers measured blood levels of a variety of antioxidants in blood samples given by the participants when the study started. They found the higher risk in men with the lowest levels of three carotenoids: alpha-carotene; beta-carotene; and lycopene.
Carotenoids are molecules that the body converts into vitamin A. They help provide the vivid coloring of carrots, peaches, watermelon and other fruits and vegetables. They are also popular ingredients in vitamin supplements.
The study was not designed to determine the source of the carotenoids, said study author Dr. Jing Ma, an assistant professor of medicine at Harvard Medical School.
But they "most likely came from food," Ma added. "At the time the study began, the participants were asked not to take supplements, so we most likely measured what came from fruits and vegetables."
It's not possible to say whether the carotenoids themselves were responsible for any protective effect, since "there are so many other good nutrients from fruits and vegetables other than the ones we measured," she said.
And the evidence that carotenoids in general are good for the arteries is not clear, Ma said. A recent report from the Physicians' Health Study found no relationship between carotenoid levels and risk of heart attack, she noted.
The long-term goal of the study is to help determine the role that antioxidants play in prevention of heart attack, stroke and other cardiovascular diseases, Ma said. "In a few years, we should have more definite conclusions from this study," she added.
Meanwhile, the current results support the American Heart Association position that "diet should be the source of antioxidants and not supplements," said Dr. Robert H. Eckel, a professor of physiology and biophysics at the University of Colorado Health Sciences Center. "The evidence to support the value of supplements is just not available. It is what we eat rather than what we supplement that is important."
An excellent way to choose antioxidant-rich fruits and vegetables is to go by color, Eckel said. "Colorful vegetables are where we expect a higher content," he explained, "sweet potatoes and spinach, apricots, carrots, things with an orange or yellow color."
A rundown on carotenoids and other antioxidants is offered by the American Heart Association.