Coffee – Unfortunately, your morning brew might be one of the main culprits behind your stained teeth. Coffee contains tannins, a type of chemical compound called a polyphenol, that can cause color compounds to stick to your teeth.

Tea - Like coffee, tea contains tannins that can stain your teeth. The good news is that there’s a simple way to cut down on tea’s tooth-staining abilities. One 2014 study found that adding 2 percent milk to tea can significantly reduce the ability of tea to stain teeth.

Berries and fruit juices - Blackberries, blueberries, pomegranates, and other dark berries contain a dark pigmentation that can cause staining on teeth. Like deep-colored fruits, dark-pigmented juices — like cranberry, grape, beet, pomegranate, and blueberry — can also discolor your teeth.

Dark cola - Regularly sipping on a can of cola can also cause your teeth to become discolored. That’s because acidic drinks like soda can cause erosion of your enamel. 

Energy and sports drinks - According to one 2012 study, both energy drinks and sports drinks are associated with the breakdown of enamel, which contributes to stains. This study also indicated that energy drinks seem to have higher acidity and enamel dissolution associated with them than sports drinks.

Red wine - The acidic nature of this beverage can “etch” the enamel and allow the dark red particles of wine to adhere to its surfaces.

Tomato-based sauces - If you want to keep your pearly whites looking their best, you may want to take precautions when eating tomato-based sauces like the kind you typically have on pizza or spaghetti. Not only are tomato-based sauces bright in color, but they’re also acidic. Rinsing your mouth out with water after eating this kind of sauce can help prevent your teeth from getting stained.

Soy sauce and balsamic vinegar - Dark-pigmented sauces like soy sauce and balsamic vinegar are also known to stain teeth. The high acid content in foods like vinegar can cause the enamel to break down, allowing a stain to set in.

Sweets and candy - Sweets and candy, especially dark varieties like chocolate, can cause mild staining to your teeth.

Additionally, a lot of hard and gummy-type candies contain colored dyes that can settle on your enamel.