Perfectly white teeth are impossible, at least in nature. That’s why it looks a little unnatural when someone whitens their teeth to the point where they practically outshine the rest of their face. But while a perfect white looks weird, the off-white of natural enamel is still widely considered an attractive and healthy color, certainly more so than yellow or dark brown.
But while unhealthy things like cavities can stain and darken teeth, and while teeth naturally yellow with age as the enamel erodes and reveals the yellow dentin beneath, there are also several otherwise healthy (and a few unhealthy) foods that can leave long-term stains on teeth. How bad the stains can get and how much it takes to stain can change depending on the source.
Tannin is a kind of chemical that many families of plants produce. The name comes from the fact that people first found it in oak trees (called “tanna” back in the day) and used it to tan animal hides into leather.
Aside from oak trees, you can find tannin in several kinds of food. Wine can contain tannin depending on where you grow the grapes and whether it’s aged in oak barrels. Beer, coffee, and tea also have tannin, and so do walnuts and most dark-colored berries. Most of these foods are good for you, but the tannin in them can darken your teeth over time.
Tobacco smoke (or any other kind of smoke, really) involves breathing dark particles of ash through the mouth and into the lungs. In the lungs, these particles will stick to your cells and make it harder to breathe, but that’s not the only place where they stick. Smoking darkens your teeth as well, plus it makes your breath smell and makes it harder to taste food on top of everything.
Several kinds of metal have a way of changing the color of enamel after a certain amount of exposure. If you work at a foundry or take a lot of iron supplements, your teeth might turn black. Copper can turn teeth green, and you can sometimes find copper compounds in mouthwashes. Silver nitrate can cause gray stains, and even too much fluoride can lead to white and then brown stains.
With so many ways to stain your teeth in the world, you have a choice to make: do you avoid everything that could possibly stain your teeth and stay away from even healthy things like fruits, nuts, and fluoride toothpaste? Or do you accept the risks, remember to brush your teeth regularly, and see a dentist regularly to clean, fill, and whiten your teeth when necessary? The answer is up to you.