Nearly one in every ten people experience kidney stones. They can be very painful, but there are ways to prevent them. Learn more about the risk factors for developing calcium oxalate stones and what changes you can make to your diet to help avoid them.*  

How Do Calcium Oxalate Stones Form?

Many foods you eat naturally contain a substance called oxalate. Your body uses what it needs from the food, and the rest becomes waste in your bloodstream. Your kidneys can remove the waste and create urine, a combination of solid waste and fluid. However, if there is too much waste in too little liquid, crystals begin to develop, stick together, and form a solid mass called a kidney stone.

What are the Risk Factors for Developing Calcium Oxalate Stones?

Calcium oxalate stones can develop for a variety of reasons. Some of the most common reasons include:

• Dehydration (not consuming enough water or fluid)
• A diet too high in protein, oxalate, sodium, and sugar
• Obesity and weight issues
• Kidney-related medical conditions like Dent disease and hyperparathyroidism
• Digestive conditions such as inflammatory bowel disease (IBD) 
• Gastrointestinal surgeries like gastric bypass

What Can I Do to Decrease the Chance of Stones Forming?

Before making any changes, it is important to speak with your doctor. In general, there are several dietary choices that may decrease your risk, such as:

• Staying hydrated. Drinking enough non-caffeinated fluids will thin out your urine and make it difficult for waste to build up and form crystals.
• Avoid eating too much protein, such as meat and poultry. In general, three ounces (approximately the size of a deck of cards) of cooked lean meat is recommended at each meal.
• Eat less salt with your meals. Too much sodium leads to excessive calcium in your urine, which can cause crystals to develop. Check the sodium content on the nutrition label when purchasing foods and try to limit sodium intake to less than 2300 milligrams per day. 
• Make sure to keep calcium-rich foods in your diet. While this may seem counterintuitive, calcium can bind with oxalate in the stomach and intestines and prevent it from being absorbed and forming stones in the kidneys. Dairy products, such as yogurt, milk, and cheese are good sources of calcium. 
• Talk to your doctor before taking a vitamin C supplement. Too much vitamin C can cause high amounts of oxalate in the urine.
• Reduce oxalate levels. Eat less oxalate-rich foods, such as nuts, beets, chocolate, soy milk, buckwheat flour, and sesame seeds. Consider combining calcium-rich food with oxalate-rich food to decrease the risk of crystals forming.

These tips are provided as general recommendations. If you want specific diet guidance, a registered dietitian can give you personalized advice on what to eat with kidney stones and CKD. 

*Calcium Oxalate Stones. (2021, July 26). National Kidney Foundation. https://www.kidney.org/atoz/content/calcium-oxalate-stone