Dr. Victoria J. Burley
Medscape Medical News > Neurology
Megan Brooks
April 08, 2013
Eating more fiber may lower the risk of stroke, according to the first meta-analysis of relevant research on fiber intake and stroke.
“We found that across the normal range intakes, with each additional 7 grams per day consumed, risk of stroke was reduced by about 7%,” Victoria J. Burley, PhD, senior lecturer in nutritional epidemiology, School of Food Science and Nutrition, University of Leeds, United Kingdom, told Medscape Medical News.
“This sounds quite a small reduction in risk, but because stroke affects so many people, lowering risk by 7% could potentially impact many thousands of individuals,” Dr. Burley noted.
The results, published March 28 in Stroke, support dietary recommendations to increase intake of total dietary fiber, the researchers say.
Large Potential Impact
Previous studies have shown that dietary fiber may help reduce stroke risk factors, including high blood pressure and elevated low-density lipoprotein cholesterol levels.
Dr. Burley and colleagues analyzed 8 relevant cohort studies from the United States, Europe, Australia, and Japan published between 1990 and 2012, comprising more than 200,000 individuals. Follow-up ranged from 8 to 19 years, and case numbers ranged from 95 fatal strokes to 2781 incident events.
Total dietary fiber intake was inversely associated with risk for stroke (hemorrhagic plus ischemic). The pooled relative risk (RR) per 7-g/d increase was 0.93 (95% confidence interval [CI], 0.88 – 0.98), with some evidence of heterogeneity between studies (I 2 = 59%).
Four studies reported ischemic stroke risk. A protective association for total dietary fiber was seen in both Japanese women (RR, 0.73; 95% CI, 0.55 – 0.97) and Swedish men (RR, 0.69; 95% CI, 0.49 – 0.96). In the Nurses’ Health Study, the risk estimate was less than 1, but the CIs were wide (RR, 0.78; 95% CI, 0.56 – 1.09), “reflecting the uncertainty about the role of fiber in this cohort,” the researchers say. No association was evident in a cohort of male smokers.
Three studies reported on hemorrhagic stroke, with evidence of a protective effect seen in 1 study for intracerebral hemorrhagic stroke in Japanese women.
“The relationship between dietary fiber and stroke risk seems to be linear, so this means that even small increases in intake may have an effect on long term stroke risk,” Dr. Burley told Medscape Medical News.
“Most populations in high-income countries, such as the US, don’t eat enough fiber-rich foods and clinicians should encourage patients to improve their intake of fruits and vegetables, whole grains, legumes, and nuts and seeds to achieve fiber goals. Meeting the guideline for dietary fiber intake is likely to have other health benefits, such as good digestive health, lowering blood cholesterol, and stabilizing blood glucose. In the long term, our data suggest that risk of stroke may be reduced as well,” she added.
The researchers did not find an association with soluble fiber and stroke risk and lacked enough data on insoluble fiber to draw any conclusions.
Best Type of Fiber Uncertain
Reached for comment, Gustavo Saposnik, MD, director, Stroke Outcomes Research Center, St. Michael’s Hospital, University of Toronto, Ontario, Canada, said that the most important finding was the 7% reduction in the incident risk of stroke for every 7 g of daily fiber consumption.
“The authors explained this is achievable by eating a small portion of whole-meal pasta (70 g), a piece of fruit (apple/pear/orange) plus a serving of tomatoes each day,” he noted.
Dr. Saposnik, who wasn’t involved in the study, said it’s “uncertain the type of fiber associated with the benefits. Since this association was identified from cohort studies, further prospective studies are needed before reaching a conclusion on the magnitude of the benefit,” he cautioned.
The UK Department of Health for England and Kellogg Marketing and Sales Company (UK) Ltd. funded the study. The authors and Dr. Saposnik have disclosed no relevant financial relationships.
Stroke. Published online March 28, 2013. Abstract