But black teas, like chai, do have a downside: They can stain teeth—even more so than coffee. Like red wine, black tea contains a great deal of tannins, dark-colored bitter plant substances that bind to teeth, leaving behind a yellow tint. But fear not, black tea lovers, this doesn’t mean you need to switch to another variety if you want to keep your pearly whites, well, white. There’s a simple, science-backed fix: add some cow’s milk to your mug—at least that’s what a recent report in the Journal of Dental Hygiene suggests.
To come to this discovery, researchers analysed the color of extracted human teeth before putting them into a solution of either tea or tea with milk for 24 hours. At the end of 24 hours, the researchers re-analyzed the color of the teeth and discovered that the chompers in the weight-loss tea and milk mixture were far more vibrant than their tea-only counterparts. In fact, the researchers say that the addition of milk is far more effective than whitening toothpaste and equally effective as some bleaching products at keeping teeth white.
The research team says the casein, a type of milk protein, is to thank. It binds to the stain-causing tannins, which keeps teeth from yellowing. Gotta love science when it keeps you looking your best.