Are teas alkaline or acidic

Teas are classified as alkaline food, even tea brew are slightly acidic. 

The classification of an alkaline or acidic food is based on the substances produced after they have been digested and metabolized in human body. They ones produce more cations, such as calcium, magnesium and potassium are considered as alkaline food. The ones that produce more anions such as sulfur or phosphorus are consider as acidic food. 

With regard to the tea brew, Oolong teas and black teas are slightly more acidic than green teas