By Alan Mozes
For every 7-gram bump in daily fiber consumption, an individual's risk for experiencing an initial stroke appears to plummet 7 percent, the investigators concluded after analyzing 20-plus years of research.
"This is important because most people in the U.S. do not eat enough fiber-rich foods," said study co-author Victoria Burley, from the Center for Epidemiology & Biostatistics at the University of Leeds in England.
"Total dietary fiber intake should be 25 to 30 grams a day from food, but on average people in the U.S. are getting only half this amount," Burley said.
Most people would have little trouble increasing overall fiber intake by 7 grams a day, the team concluded. A wide range of everyday foods -- for example, a serving of whole-wheat pasta plus a piece of fruit and a standard serving of tomatoes -- would enable people to reach this goal, the authors said.
The finding builds on prior evidence that has indicated consumption of plant-based dietary fiber -- including fruits, nuts, vegetables and whole grains -- may curb key factors that raise stroke risk, such as high blood pressure and elevated levels of so-called "bad" (LDL) cholesterol.
Strokes occur when a clot blocks a blood vessel to the brain or when a blood vessel bleeds into the brain. Stroke and other brain-based blood vessel diseases are collectively the world's second-leading killer, causing more than 6 million deaths annually and leaving large numbers of people with lasting disability.
"Everything that may be done, however small, to improve prevention is important and could have an impact on many thousands of lives," Burley said. This is particularly true for people already at risk of stroke, such as smokers, obese individuals and those with high blood pressure, the study noted.
For the study, published in the May issue of Stroke, the investigators pored over the results of eight prior studies conducted in the United States, Japan, Europe and Australia. All were published between 1990 and 2012.
Overall, the study team found that the more total dietary fiber consumed, the lower the risk of a first stroke.
However, the researchers were unable to tease out which particular fiber-rich foods might offer the most protective benefit, given a lack of food-specific data in the studies reviewed. More research would be needed to come up with an ideal stroke-prevention grocery list.
The analysis also only looked at the potential benefit of fiber obtained directly from foods, rather than from supplements, "so we can't say that fiber supplements would provide the same benefit as eating fiber-rich foods," Burley cautioned.
"Increasing your fiber intake doesn't necessarily mean wholesale change to your diet," Burley stressed. "It might just mean switching from white bread to whole-meal, or from corn flakes to bran flakes."
Such simple measures convey many benefits, she said. "We have found that stroke risk is reduced with even small increases in fiber intake, particularly if you are starting from a very low initial intake," she added.
Lona Sandon, a registered dietitian and an assistant professor of clinical nutrition at the University of Texas Southwestern Medical Center at Dallas, said the British review "comes back to what we've been telling people for years."
"This isn't about running out and getting some Metamucil," she said. "This is all about making healthier food choices and moving towards a plant-based diet, because people just aren't eating enough fruits and vegetables."
Fiber is tied up with foods that are healthful for all sorts of complex reasons, so it's hard to say fiber alone offers this kind of stroke protection, Sandon added.
"But in the end this is about getting down to basics: eating four to five cups of fruit a day, making half your grains whole grains, that kind of thing," she said. "If you want to be healthy, we know this works."