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 fifth of caffeine intake (about three cups of coffee a day) had roughly 25-30 % lower risk of developing a first stone than those in the lowest fifth. When researchers looked at 24-hour urine samples, higher caffeine consumers produced more urine and lower supersaturation of calcium oxalate and uric acid, despite a small rise in urinary calcium.
In practice:
- One to three cups of regular coffee per day fit easily into a stone-prevention plan.
- Count coffee toward your total fluid goal of 2–3 L daily.
- Keep added sugar and high-calorie creamers modest; extra calories can raise urine calcium.
- If you have been told to limit oxalate, note that brewed coffee contributes only 1–2 mg oxalate per cup—far below spinach, nuts or chocolate.
Bottom line: for most people, coffee is not a stone former—it’s a stone fighter.
| Key point | What it means |
|---|---|
| Urine volume | Coffee increases output, diluting stone-making salts |
| Calcium excretion | Tiny rise is outweighed by dilution and lower supersaturation |
| Antioxidants | May protect against crystal clumping |
| Daily use | 1–3 cups safe; stay hydrated overall |