What causes kidney stones?
Last updated September 3, 2026.
Kidney stones form when urine gets concentrated enough for minerals to crystallize - and the single biggest driver is not drinking enough water. Most stones are calcium oxalate, and dietary calcium is usually not the villain: the big dietary risks are excess salt, heavy animal protein, and high-oxalate foods in susceptible people, while normal food calcium protects by binding oxalate in the gut. Other types track other causes: uric acid stones with gout, struvite stones after urinary infections, cystine stones genetic. Risk multipliers: family history, prior stones, obesity, diabetes, gut surgery, hot climates, and sweaty jobs. If you pass a stone, get it analyzed - the type names your prevention lever. Pymander is a free AI doctor, 24/7 by text, and can help you map your risk.
What to do
- Drink to pale urine: dilute urine is the core prevention - aim for urine that stays light-colored all day.
- Cut salt before calcium: salt pushes calcium into urine; normal food calcium is protective.
- Go easy on animal protein and high-oxalate foods: spinach, beets, nuts, and chocolate for susceptible people.
- Save and analyze any stone you pass: straining your urine sounds grim and is genuinely useful.
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