To maintain teeth whitening results, it is important to maintain a white diet, especially in the first 72 hours following teeth whitening, as the enamel is porous during that time and it can actually pick up more stains. In a white diet, things to avoid are red wine, colas, coffee, tea, even dark-stained fruits such as tomatoes, plums, cherries, blueberries. These substances can actually also stain teeth.