Foods That Could Cause Kidney Stones

If you are one of the approximately 9% of adults in the U.S. who has had a kidney stone, you are probably well aware of how painful it is (via European Urology). According to the National Institute of Diabetes and Digestive and Kidney Diseases (NIDDK), kidney stones are hard pieces of material that form in your kidneys and pass through your urinary tract. Your kidneys act as your body's filtration system — they get rid of toxins and excess minerals through your urine (per Kidney Research UK). However, certain materials that your kidneys need to filter out can sometimes form crystals that in turn can gather together and form small stones (per Johns Hopkins Medicine). Some common symptoms of kidney stones include sharp pain in your back, side, lower abdomen, or groin (per NIDDK). Other symptoms can be difficulty urinating or constant need to urinate, cloudy or bad-smelling urine, or bloody urine.

Not all kidney stones are the same. The NIDDK explains the four main types. Calcium stones are the most common, and they are made from calcium and either oxalate or phosphorus. Uric acid stones are the second most common – uric acid results when your body breaks down purines, substances that are naturally found in your body as well as in some foods. Struvite stones — consisting of magnesium, ammonium, phosphate, and calcium — are rare. Cystine stones are also rare and only form if you inherited the rare disorder cystinuria, which causes high cystine levels in the urine. The foods you may want to avoid would therefore depend on the type of kidney stones you have had, but we've rounded up a list of some of the common culprits that might contribute to these uncomfortable deposits.

This one may be a bit painful to read: Yes, according to Harvard Health Publishing, chocolate is a food that contains high concentrations of oxalate, and eating it thus increases the chances for calcium oxalate kidney stones. That said, the MCW states that the goal of the low-oxalate diet is to avoid a very high concentration of oxalate in the urine. One way to combat this and to still enjoy high oxalate foods is to eat small amounts of them at different points throughout the entire day, rather than consuming a large quantity at once. So, having a few small pieces of chocolate over the course of your day may be much safer than eating a couple of brownies in one sitting. 

If even that approach cannot satisfy your sweet tooth, there are an abundance of dessert options that do not include chocolate. Low-oxalate dessert options from The Kidney Dietician  include vanilla ice cream, apple crisp, oatmeal cookies, and butterscotch pudding.

As noted by a review in Advances in Nutrition, research on the relationship between caffeine consumption and kidney stones has yielded conflicting results. On the one hand, coffee and tea have significant amounts of oxalate. On the other hand, they are fluids that help flush out your system and prevent kidney stones. However, what has been found consistently in the literature is that decaffeinated coffee is associated with a lower risk for kidney stones. So you might want to start your day with a decaf cup of Joe.

Black tea might increase the risk for calcium oxalate stones if you have six or more cups per day, according to an article in the Asia Pacific Journal of Clinical Nutrition. In addition, one study in the Journal of Food Composition and Analysis found that green tea has about the same amount of oxalate as black tea. Herbal and iced teas were found to have a much lower oxalate concentration, alongside other caffeinated drinks like sodas and sports drinks. 

Some nuts, nut butters, and seeds tend to be high in oxalate which can lead to calcium oxalate stones, according to the NIDDK. The Kidney Dietician reports that those highest in oxalate are Brazil nuts, cashews, hazelnuts, pine nuts, chia seeds, and sesame seeds. In addition, the site notes that not only are almonds high in oxalate, but so are products derived from them, such as almond butter, flour, and milk.

However, there are a number of other nuts and seeds you can enjoy that have lower concentrations of oxalate. These include macadamia nuts, pecans, pistachios, and walnuts. Some seeds that have lower levels of oxalate are sunflower seeds, pumpkin seeds, and flax seeds. If you like to snack on nuts but have a history of calcium oxalate stones, low oxalate beans can make great snacks. Dried peas, or roasted and seasoned chickpeas can provide the perfect afternoon crunch.

You don't need to avoid all types of starches to stave off kidney stones, and it's vital that you take in enough carbohydrates for energy. However, there are some that are particularly high in oxalate and thus can cause calcium oxalate stones. University of Michigan Health System (UMHS) recommends avoiding bran or high-fiber cereal, whole wheat, and buckwheat among others because they have high levels of oxalate.

As an alternative, you can consume in limited quantities starches that have moderate levels of oxalate. A few of the ones suggested by UMHS include brown rice, corn, spaghetti in red sauce, and white bread. If you are looking for breakfast foods to replace your bran cereal, you can enjoy bagels and oatmeal. And The Kidney Dietitian notes that oatmeal is great for people who are trying to avoid kidney stones. This is because it is high in magnesium, which can help prevent calcium oxalate stones, as shown in a study in Biological Trace Element Research.

While having enough protein in your diet is important, too much animal protein can increase your risk for kidney stones, according to a review in Nutrients. And some data shows that most of the protein Americans consume is animal protein — 67% of protein intake in the U.S. is from animal sources, with 33% coming from plant-based protein (via Current Developments in Nutrition).

If you have a history of uric acid stones, you want to consume smaller portions of animal protein. This is because acid is a byproduct when your body metabolizes this kind of protein, according to The Kidney Dietician, and more acid in your body means a higher chance of uric acid kidney stones. In particular, you want to limit foods such as red meat, processed meats, poultry, and organ meats. She recommends having no more than 6 ounces of these meats per day. And one organ meat in particular packs a double whammy of things you want to avoid: In addition to delivering animal protein, liver also has moderate amounts of oxalate according to University of Michigan Health System, so you might want to curb the liver and onions for dinner.

Vitamin C has been thought to cause kidney stones because it could increase the oxalate in your urine (via Nebraska Medicine). However, dietary vitamin C does not appear to be a risk factor for kidney stones, according to one study in the American Journal of Kidney Diseases. With regard to vitamin C supplements and kidney stone risk, the research yields mixed results. One study in Antioxidants found that intravenous vitamin C was not associated with kidney stones. However, an 11-year-long study in JAMA Internal Medicine found that men who took high-dose vitamin C supplements were twice as likely to get kidney stones. If you are taking or thinking about taking dietary supplements in general, the Dayton Daily News notes it is important to tell your doctor. They can help you to avoid potentially harmful interactions with medication or other potential health problems that can be caused by supplementation.

According to the NHS, you likely do not need to take vitamin supplements if you consume a balanced diet. Fruits and vegetables like strawberries, broccoli, red pepper, or an orange should give you the vitamin C you need (via Mayo Clinic). Further, The Kidney Dietitian notes that eating fruit also ups your potassium intake, which might also reduce the risk of kidney stones.