Some plants have a chemical that binds to calcium in your blood, making your bones weaker and causing painful kidney stones.

Oxalates are plant-derived compounds that can bind with calcium in the kidneys to form calcium oxalate kidney stones.

Kidney stones are often made of calcium oxalate, and even small increases in oxalate in your urine can make stones more likely to form—much more than similar increases in calcium—because your body naturally has way less oxalate to begin with.