Worried about having dandruff? Don't worry, here are 9 tips for preventing dandruff, you must watch! 1. Avoid foods such as fried, greasy, spicy, alcohol and caffeine, which can stimulate the formation of oil and scalp, so you should give up. 2. Quit sweet foods. Because the hair is alkaline and the dessert is acidic, it will affect the acid-base balance in the body..