When kidney calculi and bladder stones occur, patients often seek advice from doctors in severe pain: Where do stones come from the kidneys and urethra? How can we prevent postoperative recurrence? The main reason for the formation of kidney calculi is diet. It is caused by too many related ingredients that can form stones in the diet. A more detailed explanation is that oxalic acid accumulates too much. The accumulation of oxalic acid in the body is one of the factors leading to kidney calculi. Such as spinach, beans, grapes, cocoa, tea, oranges, tomatoes, potatoes, plums, bamboo shoots and other things that people generally like to eat are foods with high oxalic acid content. Doctors found through research that 200 grams of spinach contains oxalic acid 725/question/1450002.html.