Recently, the International Journal of Dental Research published a new Canadian study finding that adding milk to tea can keep teeth white.
In the new study, Dr. Eva Chow from the University of Alberta's Faculty of Dentistry used extracted human teeth to study the effects of tea and milk on dental health. Dr. Chow analyzed and recorded the initial color of the teeth, then soaked them in tea or tea with milk for 24 hours, with the water temperature maintained at 37°C. After 24 hours, Dr. Chow again analyzed and recorded the color of these "stained" teeth. Comparative analysis found that the teeth soaked in tea were significantly darker than those soaked in tea with milk, with the latter remaining white.
Dr. Chow pointed out that tannins, water-soluble compounds in tea, can stain teeth yellow, while adding milk to tea can reduce the tea's ability to discolor teeth.