The International Journal of Dental Hygiene published a new Canadian study finding that adding milk to tea can keep teeth white.
In the new study, Dr. Eva Zhou, a researcher at the Faculty of Dentistry at the University of Alberta in Canada, used extracted human teeth to study the effects of tea and milk on dental health. Dr. Zhou 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. Zhou analyzed and recorded the color of the "stained" teeth again. Comparative analysis found that the teeth soaked in plain tea were significantly darker than those soaked in tea with milk, with the latter remaining white.
Dr. Zhou pointed out that tannins, water-soluble compounds in tea, can stain teeth yellow, while adding milk to tea can reduce tea's ability to discolor teeth.