If you’re looking to keep your mind sharp, simply having two or more cups of green tea can help do the trick. Recent research found that regular tea drinkers who consume at least two mugs a day reduce their risk of developing dementia by nearly 30 percent. Although it’s not known exactly why green tea should have this protective effect, it does contain flavonoids, which help maintain the health of blood vessels that ‘feed’ the brain, as well as caffeine, which boosts mental awareness.