Worried that your daily cup of green tea might lead to kidney stones? Relax: studies consistently show that green tea does not raise the risk, and may actually lower it. How kidney stones formStones develop when urine becomes oversaturated with calcium, oxalate, uric acid, or other solutes. Low urine volume, high sodium, and low citrate are common culprits. Green tea’s chemistryGreen tea contains caffeine, catechins, and small amounts of oxalate. The caffeine boosts urine output, while catechins act as antioxidants that interfere with crystal clumping. The oxalate in one cup is modest—far below what is found in spinach, nuts, or... Learn more