New research says that a 7% increase in daily fiber results in a 7% reduction of stroke risk.
... each 7-gram per day increase in fiber intake reduced the risk for a first stroke by about 7 percent. The findings were published in the journal Stroke.
Water soluble fiber — the kind found in beans, nuts and other foods — reduced the risk substantially, and insoluble fiber and cereal fiber reduced it slightly. Fruits and vegetables contain both types of fiber, though there was not enough data on those foods considered separately to draw valid conclusions about their effect. [emphasis mine]