The head of the Gastrointestinal Cancer Research Center at Tehran University of Medical Sciences:

Drinking tea at a temperature higher than 65 degrees Celsius increases the risk of developing esophageal cancer; it is recommended that tea be consumed at least 3 minutes after it is poured.

He added that a study on 50,000 people in Iran confirmed this link. Also, drinking 3 to 6 cups of tea daily may be beneficial for heart health and increased focus, but drinking very hot tea is harmful.