My dh used to drink a lot of coffee when he was in the Navy. Started having stomach issues and the doctor told him the acidity of the coffee was ruining his digestive system. He switched to tea.
I used to drink coffee with milk and sugar in it, then started having digestive problems. A cousin mentioned having the same problem and said his doctor advised him to switch to black coffee. I did that and *poof!* the digestive problems I had disappeared.
I tried green tea for awhile, but it discolored my teeth. Not sure if it was the brand or what.....
To my mind, there is really no need to add anything to tea or coffee (well, maybe a slice of lemon with black tea). It's a matter of getting accustomed to the taste. I get so much sugar from other sources, such as ice cream, I don't want it in my coffee too.