Several common foods can raise your risk of kidney stones, but the biggest culprits depend on which type of stone you’re prone to. For the most common kind, calcium oxalate stones, the main dietary drivers are high-oxalate foods, excess salt, large amounts of animal protein, and sugary drinks high in fructose. Low fluid intake ties it all together by concentrating these substances in your urine.
High-Oxalate Foods
Oxalate is a natural compound found in many plants. When it builds up in your urine, it binds with calcium to form crystals, and those crystals can grow into calcium oxalate stones, the type responsible for roughly 80% of all kidney stones. The foods highest in oxalate include spinach, rhubarb, beets, almonds, soy products (tofu, miso, soy milk), and Swiss chard.
That doesn’t mean you need to eliminate every one of these foods. The smarter strategy is to eat calcium-rich foods at the same meal. When calcium and oxalate meet in your gut, they bind together there and leave your body through stool instead of being absorbed into your bloodstream and filtered through your kidneys. The National Kidney Foundation recommends eating enough dietary calcium to lower oxalate absorption rather than following a strict low-oxalate diet.
Too Much Salt
High sodium intake is one of the most underappreciated causes of kidney stones. In the part of your kidney responsible for regulating calcium, sodium and calcium travel together. When you eat a lot of salt, your kidneys excrete more sodium, and calcium gets dragged along with it. That extra calcium in your urine raises the concentration of the raw materials stones are made from.
Processed foods, canned soups, deli meats, frozen meals, and restaurant dishes are the biggest sources of hidden sodium for most people. Cutting back on these foods reduces the amount of calcium your kidneys dump into your urine, which directly lowers your stone risk.
Animal Protein
Eating large amounts of meat, poultry, fish, shellfish, and eggs contributes to kidney stones in two ways. First, animal protein makes your urine more acidic, which encourages uric acid to crystallize rather than stay dissolved. Second, purines (compounds found in high concentrations in organ meats, shellfish, and red meat) break down into uric acid, increasing its levels in your urine.
This is especially relevant if you’ve had uric acid stones, the second most common type. The NIDDK recommends limiting beef, chicken, pork (particularly organ meats), eggs, fish, and shellfish. You don’t need to go vegetarian. Replacing some animal protein with plant-based options like beans, lentils, nuts, and tofu can shift the balance enough to matter. Maintaining a healthy weight is also important here, since excess body weight increases uric acid production.
Fructose and Sugary Drinks
Fructose has an independent link to kidney stone formation that other carbohydrates don’t share. A large study tracking three separate groups of participants found that people in the highest category of fructose intake had a significantly greater risk of developing kidney stones compared to those who consumed the least. Non-fructose carbohydrates showed no such association.
The biggest sources of fructose in most diets are soft drinks and other beverages sweetened with high-fructose corn syrup, fruit juices with added sugars, and heavily sweetened processed foods. Whole fruit contains fructose too, but in much smaller amounts alongside fiber and beneficial nutrients, so it’s a different story than drinking a 20-ounce soda.
The Calcium Paradox
This is the part that surprises most people: eating more calcium from food actually protects against kidney stones. Women in the highest category of dietary calcium intake had a 65% lower risk of forming stones compared to women who ate the least calcium. The reason is straightforward. Calcium from food binds oxalate in your digestive tract before it ever reaches your kidneys. When people restrict dietary calcium hoping to prevent stones, they absorb more oxalate, and their risk goes up.
Calcium supplements, however, tell a different story. Taking supplemental calcium has been linked to a 17 to 20% increase in stone risk. The likely explanation is timing. Supplements taken between meals don’t encounter much oxalate in your gut, so the extra calcium gets absorbed into your blood and eventually filtered through your kidneys, raising urinary calcium levels. If you take calcium supplements, taking them with meals helps mimic the protective effect of dietary calcium.
Foods and Drinks That Help
Citrate is a natural stone inhibitor. It binds to calcium in your urine and prevents crystals from forming. Many fruits and vegetables are rich in citrate, including lemons, oranges, grapefruit, grapes, kiwi, melons, pomegranates, tomatoes, bell peppers, and carrots. Adding lemon juice to your water is one of the simplest ways to boost your citrate intake throughout the day.
Fluid intake matters as much as food choices. The goal is to produce more than 2.5 liters (roughly 85 ounces) of urine per day, which typically means drinking about 3 liters of fluid. Water is ideal. The relationship between urine volume and stone risk is continuous: the more dilute your urine, the harder it is for crystals to form. Without adequate hydration, even a perfect diet won’t fully protect you. Five-year recurrence rates for kidney stones run as high as 40%, and staying well hydrated is the single most effective prevention measure.
Putting It Together
Kidney stone prevention isn’t about eliminating one food. It’s a pattern. The dietary changes that matter most are drinking enough fluid to keep your urine dilute, eating calcium-rich foods with meals, moderating salt and animal protein, and cutting back on fructose-sweetened drinks. High-oxalate foods like spinach and almonds are fine for most people as long as they’re paired with calcium at the same meal. If you’ve had a stone analyzed and know the type, you can tailor your approach: focus more on oxalate management for calcium oxalate stones, or on reducing purines and animal protein for uric acid stones.