Is Coffee Good for Kidney Stones? If you like starting your day with coffee and have worried about stones, the news is reassuring: sensible coffee drinking is linked to fewer stones, not more. Stones form when urine becomes too concentrated with calcium, oxalate or uric acid. Anything that increases urine volume or lowers supersaturation usually helps. Coffee does both. The caffeine acts as a mild diuretic, diluting the urine, while antioxidants in the brew interfere with crystal clumping. Large prospective cohorts show the benefit clearly. Among more than 200 000 health professionals followed for eight years, people in the highest... Learn more