Yellow teeth can instantly age you. Your choppers constantly deal with pigment-inducing beverages such as tea, coffee, and wine; even the acids in sport drinks can lead to Stainville. “Teeth stain as soon as staining food is consumed,” says John Koutsoyiannis, DDS, and head cosmetic dentist at SohoSmile in New York City. To combat yellowing, eat strawberries which contain teeth-whitening malic acid. Koutsoyiannis also suggests brushing with baking soda twice a month or rinsing with lemon water. If you must down a sport drink after a grueling workout, lessen the damage by drinking from a water bottle with a straw (Camelbak, $15).