Calcium oxalate kidney stones are one of the most painful conditions in the urinary tract and have plagued humans for thousands of years. According to National Kidney and Urologic Diseases Information Clearinghouse (NKUDIC), evidence of some type of kidney stones was found in a 7,000-year-old mummy. The NKUDIC, a subprogram of the U.S. Department of Health and Human Services, goes on to say that each year more than half a million Americans visit the emergency room for kidney stone issues.
Rhubarb, spinach, beets, Swiss chard, wheat germ, soybean crackers and peanuts are the foods that contain the highest amount of oxalate. While doctors don't know whether an over consumption of these foods will cause calcium oxalate stones among people who are not susceptible, they can be dangerous to people who are susceptible, such as those with a family history of kidney stones. People are at higher risk of developing the stones if they consume raw rhubarb, spinach and beets, as well as other oxalate-containing raw foods. Cooking the vegetables may reduce the risk.
Okra, chocolate, black Indian tea and sweet potatoes are also considered high-risk foods. With all kinds of foods containing oxalates, doctors say the risk of developing kidney stones is more likely if those consuming them are prone to an inflamed bowel or underwent an intestinal bypass or ostomy surgery. Peanuts are among foods that require a strong digestive tract to extract all the nutrients, according to the World's Healthiest Foods. The better you are at digesting, however, the more likely you will be at absorbing the peanuts' oxalate.
Grits, grapes, celery, green pepper and red raspberries are among the medium-risk foods that contain oxalate. Vegetables are among the food most commonly containing oxalate. While oxalate can be found in meat, animal isn't contained in top foods containing the most oxalate. Oxalate can be found in every part of celery and green pepper, whether it is the stems, seeds or leafs. While fruit isn't as commonly associated with oxalate, it can be found in all areas of the plant as well.
Fruit cake, strawberries, marmalade and liver are also among the medium-oxalate producers in the top 20 list. With the exception of liver, all of the lower oxalate containing foods are either fruit or they are made with fruit. Over half of the top 20 foods that contain oxalate are fruit or vegetable products.