By the way, doctor: Should I quit drinking tea to avoid getting kidney stones?
Q. Two of my friends suffer from kidney stones. Each was advised to give up tea. I drink a lot of tea. Am I in danger of getting kidney stones?
A. Your kidneys get rid of excess minerals — calcium and potassium, for example — from the bloodstream. Various compounds in the urine prevent the minerals and other substances from sticking together, but sometimes they still manage to find each other and clump together. The result is a kidney stone.
About 75% of all kidney stones are made of calcium and oxalate, a substance found mainly in plant foods. About half the time, such stones form because of high levels of calcium in the urine, which is probably an inherited tendency.