getting enough liquid in your system is super important since your brian is about 80% water. it won't function as well if you're dehydrated. so make sure to keep drinking water all day, at least 8 6-ounce glasses. it's also a good idea to drink to fruit or vegetable juice. polyphenols, which are the antioxidants in fruits and vegetables, can help protect brain cells from damage and keep your brain at a high-functioning level.