Coffee is another unsurprising source of stains, and it’s also- you guessed it- fairly acidic. Compared with smokers and tea drinkers, stains on the teeth of coffee drinkers are often more resistant to bleaching or whitening, and more likely to become stained again after treatment.
Foods that help:
It’s not technically a food, but it is a great weapon against decay-causing acid. Chewing sugar-free gum after meals stimulates saliva production, which helps rinse harmful material and food debris away from your teeth. Sugar-free gum is often sweetened with a chemical called xylitol, which helps fight bacteria as well.
This one seems like a no brainer, but many Americans don’t drink nearly enough water. Besides helping to wash away acid and residue from your teeth, most US cities add fluoride to the tap water for extra help fighting decay.