Green tea drinkers, especially those who drink 4-6 cups per day. Do you notice your teeth becoming acidic? I guess the proper description is, your teeth seem to be losing some nerve sensation. After drinking green tea, I notice that my teeth, if I were to accidentally grind or miss my bite, literally screech like I'm scratching the chalkboard.
I notice the same with black tea but it's much more pronounced with green tea. My teeth are all in good shape, although stained with green tea and coffee. I'm not so concerned about the coffee and tea stains; I'm just concerned about the acidic sensation.
Teas are quite acidic. That's part of the reason why they stain so well compared to other drinks. Not sure which is more acidic of black or green tea though.
"You can demonstrate the purpose and limits of human digestion with a simple experiment: eat a steak with some whole corn kernels, and see what comes out the other end. It won’t be the steak."