Kidney stones are a painful condition that affects 1 out of 11 adults. Stones are formed in the kidneys from certain minerals and waste products. While a stone is traveling from the kidney through the urinary tract, significant abdominal and side pain is common. When stones are more severe, the pain is sometimes joined with nausea, vomiting, fever, and chills.
Calcium oxalate stones are the most common form of kidney stones. If you’re prone to this kind of kidney stone, several nutrition strategies may help decrease the likelihood of developing more. Learn about possible dietary changes and strategies for people with calcium oxalate kidney stones below.
What are oxalates?
Oxalates are natural compounds primarily found in plant foods. Our bodies also make a supply of oxalates. About half of the oxalate in our bodies is from the diet, and about half is produced by the body. Oxalate stones form when too much oxalate is excreted in a person’s urine.
People more at risk for calcium oxalate kidney stones
People who live in hot climates are more likely to develop kidney stones. Low fluid intake is another risk factor. Other conditions that make a person more likely to develop calcium oxalate stones include:
- Hypertension
- Gout
- Hyperparathyroidism
- Nonalcoholic fatty liver disease
- Overweight or obesity
- Gastrointestinal diseases, such as Crohn’s disease
- Bariatric surgery that causes malabsorption
Foods and drinks high in oxalates
Consuming oxalates may play a role in developing kidney stones, and limiting high-oxalate foods may decrease the risk of calcium oxalate kidney stones. However, many healthy plant foods contain oxalates, so you shouldn’t strictly eliminate oxalates from your diet. Instead, try to limit high-oxalate foods while still eating a variety of plants every day. Other strategies, like drinking enough fluids and including a source of calcium at meals, will also help reduce the chances of calcium oxalate stones.
High oxalate foods include:
- Spinach
- Chard
- Beets
- Rhubarb
- Star fruit
- Wheat germ
- Bran
- Cocoa
- Peanuts
Nutrition management strategies for oxalate kidney stones
The information below provides general guidelines to decrease the risk of calcium oxalate kidney stones. If you need more specific help, contact a registered dietitian or other healthcare professional familiar with kidney issues for personalized information based on your medical history and type of kidney stones.
Fluid Goals
Increasing fluid intake is one of the most important strategies for reducing kidney stones. Drinking more liquids increases your urine output, which helps flush out the minerals that could form stones in your kidneys.
Some guidelines suggest six to eight 8-ounce servings of liquids daily, while other references recommend as much as 2.5 to 3 liters daily as a goal. Drinks that have a neutral pH, like water, are ideal.
Note that you should check with a healthcare provider before increasing fluid intake if you’re in kidney failure or have been told to limit your fluid intake.
Limit sodium intake
Calcium and sodium share the same transport channel through the kidneys, so the amount of sodium in the diet is linked to the amount of calcium in the urine. As the kidneys filter sodium out of the body, they release some calcium into the urine, which can then form stones with oxalates.
The Dietary Guidelines for Americans recommend consuming less than 2300 milligrams (mg) of sodium per day, though you may have a stricter limit if you have chronic kidney disease.
If you haven’t already, try to reduce the amount of sodium in your diet. Check the Nutrition Facts label to choose lower sodium options, and try cooking from scratch more. Processed meats, like spam, salami, or jerkies, are usually very high in sodium. Canned and bottled sauces, like soy sauce, pasta sauce, or salad dressings, are typically high in sodium. Fresh fruits and vegetables are naturally low in sodium.
Calcium intake
For most adults, the recommended calcium intake is 1000-1200 mg per day. Good sources of calcium include yogurt, milk, cheeses, tofu, calcium-fortified orange juice, and calcium-fortified plant milk (such as almond or oat milk).
People with calcium oxalate stones don’t need to eat more calcium than is recommended for the general population. Instead, they should spread their calcium intake throughout the day, such as one serving at each meal or paired with foods higher in oxalates. For example, drink eight ounces of cow’s milk or calcium-fortified plant milk if you have a small side of sauteed spinach with dinner.
Including a calcium source with a meal helps reduce the amount of oxalate you absorb and then excrete in your urine. Some calcium and oxalate bind in the stomach and intestines before reaching the urine when eaten in the same meal or snack. Decreased oxalate levels in the urine decrease the chances of developing a calcium oxalate stone.
Vitamin C Supplements
Avoid taking vitamin C supplements if you’re prone to calcium oxalate stones. Taking too much vitamin C increases the amount of oxalate in the urine because vitamin C is partially broken down into oxalates.
Most people can easily meet their vitamin C needs from their diet alone, so they shouldn’t require vitamin C supplements daily unless prescribed by a healthcare provider. One medium orange contains 70 mg of vitamin C per serving, almost enough to meet the recommended daily intake for adults of 75 mg per day in one serving of fruit.
Multivitamins typically contain vitamin C, so mention any vitamin supplement you take to a healthcare professional if you’re having trouble with kidney stones. Be careful about taking any “immunity” blends of vitamins or teas, as they may contain supplemental vitamin C.
