Quoting from Dr. Rodman in "No More Kidney Stones", "Oxalates are a throwaway product that the body excretes in the urine. It is an ingredient in two-thirds of all kidney stones and a key troublemaker. Oxalate would be of little or no interest if it did not crystallize with calcium to form kidney stones." Some foods containing large amounts of Oxalates are: Dark green vegetables such as Spinach, green peppers, green lettuce,Kale, Collard greens,etc; Chocolates, Nuts, Pumpkin,Baked beans. This is just a partial list. I recommend buying the book. Dr. Rodman says "The Six Great Pains of Medicine are: heart attack, angleclosure glaucoma, facial nerve pain, childbirth, gallstones, kidney stones. Many people think kidney stones is the most severe of them all." I hope this helps. Tara