Adding a splash of milk to your tea — five milliliters for the perfect cup, according to the British Standards Institution — is quite an effective way to reduce stains on your teeth, says a new study published in the International Journal of Dental Hygiene — and they know a thing or two about keeping your teeth clean.
“Tea is the second most consumed drink in the world (after water), and the way it’s processed affects how teeth are stained,” the paper’s lead researcher, Dr. Ava Chow, told The Telegraph. “The more the tea is processed or oxidized, the higher its staining properties are. But we've found that the addition of milk to tea reduces the tea’s ability to stain teeth.”
Researchers tested the efficacy of milk as a protective dental agent by placing extracted human teeth in either a solution of pure tea or tea with milk for a full 24 hours. The team found that casein, the main protein in milk, actually binds to the tannins — an organic substance used to provide a bitter or dry taste —found in tea, preventing staining.
Furthermore, “the magnitude of the color change observed in our experiments is comparable to the color change seen by vital bleaching products, and more effective than whitening toothpastes.”
If you’ve been drinking your tea without milk this whole time, we couldn’t imagine a better reason to start.