Some plants have a chemical called oxalate that can form kidney stones when it mixes with calcium in the body.

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.

Dietary oxalates form insoluble calcium oxalate crystals in the renal tubules, leading to nephrolithiasis, and systemically chelate serum calcium, triggering compensatory bone resorption.