THURSDAY, Feb. 21 (HealthDay News) -- Fish oil won't help prevent a stroke, but a high-fiber diet might make a difference, say two new studies designed to assess the impact of nutrition on stroke.

"Fish oils are not as good as people claim them to be," said Dr. Craig Anderson, lead author of the fish oil study and director of the neurological and mental health division at the George Institute for International Health at the University of Sydney, in Australia.

On the other hand, "eating 20 to 35 grams of fiber per day may reduce the risk of stroke and may result in better outcomes if you do have a stroke," said Angela Besanger, lead author of the fiber study and a nutritionist at Massachusetts General Hospital in Boston.

Both studies were expected to be presented Thursday at the American Stroke Association's International Stroke Conference in New Orleans.

Every year, more than 700,000 Americans have a stroke, according to the National Institute of Neurological Disorders and Stroke (NINDS). Stroke is the third-leading killer in the United States and is the leading cause of disability.

Known risk factors for stroke include cigarette smoking, high blood pressure, heart disease and diabetes. Past research has suggested that fish oil -- either directly from fish or from supplements -- could improve cardiovascular health and possibly decrease the risk of stroke.

To assess whether or not fish oil truly has an impact on stroke risk, the Australian researchers randomized 102 people who'd had a stroke to take either a daily fish oil supplement or a placebo for 12 weeks.

They found no evidence of benefit on markers of cardiovascular risk in people taking fish oil supplements when compared to the placebo group.

"From our research and on the basis of other data, I do not recommend low-medium doses of fish oil to my patients. Conversely, though, I do not discourage them if they personally wish to take the treatment as it might encourage other lifestyle changes," Anderson said.

The fiber study, which Besanger said is the first of its kind, included 50 people who'd just had a stroke. The researchers asked them to recall everything they'd eaten within 24 hours of having a stroke and compared that information to their disability level and general health at six months.

They found that those with the highest levels of fiber intake had better outcomes, but study co-author Dr. Karen Furie, director of the stroke service at Massachusetts General, pointed out that "this wasn't a clinical trial. We didn't give people fiber. The association was pretty dramatic, but this was a small sample size, and it's only observational data. These findings need to be replicated in a larger study."

However, Furie also noted that a recommendation to increase the amount of fiber in your diet is "a recommendation that's pretty easy to endorse. There are no downsides to increasing fiber intake."

"People attracted to these ideas [more fiber and fish oil] could be healthier to begin with," said Dr. Keith Siller, an assistant professor of neurology at New York University Medical Center in New York City. "It's very hard to validate whether taking fiber or fish oil has a direct effect on stroke risk. They're probably more a marker of people that live a healthier lifestyle."

More information

To learn more about stroke and how to prevent one, visit the National Institute of Neurological Disorders and Stroke.

SOURCES: Angela Besanger, R.D., project manager, stroke service, and Karen Furie, M.D., Ph.D., director, stroke service, Massachusetts General Hospital, Boston; Craig Anderson, F.R.A.C.P., Ph.D., professor, stroke medicine, and director, Neurological and Mental Health Division, George Institute for International Health, University of Sydney, Australia; Keith Siller, M.D., assistant professor, neurology and psychiatry, New York University Medical Center, New York City; Feb. 21, 2008, presentation, American Stroke Association's International Stroke Conference, New Orleans

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