Plenty of foods can help boost cognition in the long term, but blueberries may keep your brain working well right now! Researchers from the University of Reading found people performed better on memory and concentration tests five hours after drinking a smoothie made with about one and a half cups of blueberries than they did after downing a blueberry-free concoction. Scientists believe that the berry’s flavonoid compounds improve alertness by increasing oxygen flow to the brain.