How does diet affect the risk of developing kidney stones?
Diet is one of several factors that can promote or inhibit kidney stone formation. Other factors include heredity, environment, weight, and fluid intake. The body uses food for energy and tissue repair. After the body uses what it needs, waste products in the bloodstream are carried to the kidneys and excreted as urine. Certain foods create wastes that may form crystals in the urinary tract. In some people, the crystals grow into stones.2
A kidney stone is a hard mass that builds up from those crystals. In most people, natural substances in the urine keep crystals from forming stones; in stone formers, that protection is not enough.5
For people who have had a kidney stone, preventing another will be a priority. In addition to dietary changes, a person may need medicine to prevent kidney stones. The first step in preventing kidney stones is to learn what kind of stones a person’s body typically makes.
What are the types of kidney stones?
- Calcium oxalate stones are the most common. They tend to form when the urine is acidic, meaning it has a low pH. Some of the oxalate in urine is produced by the body. Calcium and oxalate in the diet play a part but are not the only factors that affect the formation of calcium oxalate stones. Dietary oxalate is an organic molecule found in many vegetables, fruits, and nuts.
- Calcium phosphate stones are less common. Calcium phosphate stones tend to form when the urine is alkaline, meaning it has a high pH.
- Uric acid stones are more likely to form when the urine is persistently acidic, which may result from a diet rich in animal proteins and purines — substances found naturally in all food but especially in organ meats, fish, and shellfish.
- Struvite stones result from infections in the kidney. Preventing struvite stones depends on staying infection free. Diet has not been shown to affect struvite stone formation.
- Cystine stones result from a rare genetic disorder that causes cystine — an amino acid, one of the building blocks of protein — to leak through the kidneys and into the urine to form crystals.
Why is knowing which type of stone a person has important?
Knowing the chemical makeup of the stone helps the doctor identify why the patient is prone to stone formation. The kind of stone a person’s body makes determines what dietary changes may be needed. For example, limiting oxalate in the diet may help prevent calcium oxalate stones but will do nothing to prevent uric acid stones. Some dietary recommendations may apply to more than one type of stone. Most notably, drinking enough water helps prevent all kinds of kidney stones.
How does a doctor determine the type of kidney stone?
If a person can catch a kidney stone as it passes, the doctor can send the stone to a laboratory for analysis. For stones that are causing symptoms, the doctor may also retrieve a stone surgically or with a scope inserted through the urethra into the bladder or ureter.
The doctor will also order tests to look for unusual levels of chemicals such as calcium, oxalate, magnesium, and sodium in the blood and urine to help design a prevention strategy. A 24-hour urine collection also shows how strictly a person needs to follow each part of the diet below.
Fluids: how much, and which
How much fluid should a person drink to prevent stone formation?
The amount of fluid a person needs to drink depends on the weather and the person’s activity level. The American Urological Association’s guideline asks every stone former to drink enough to make at least 2.5 liters of urine a day — a little over 2½ quarts, and a little more than the 2 liters in Dr. Robbins’ 2011 note above.3 Some doctors have their patients collect urine for 24 hours so the volume can be measured. The doctor can then advise the patient about increasing fluid intake, if necessary. People who work or exercise in hot weather need more fluid to replace the fluid they lose through sweat.
NIDDK’s general advice is six to eight 8-ounce glasses a day, unless you have kidney failure, and to talk with a health care professional about how much you should drink.1
Drinking enough liquid, mainly water, is the most important thing you can do to prevent kidney stones.
NIDDK, Eating, Diet, & Nutrition for Kidney Stones
A person at risk for cystine stones should drink enough water each day to dilute the concentration of cystine that escapes into the urine, which may be difficult. More than a gallon of water may be needed every 24 hours.
What fluids protect against kidney stone formation?
Water is an inexpensive and calorie-free protection against kidney stones. Spreading it through the day helps, including a glass at bedtime and another if you get up at night to use the bathroom.
Some studies suggest citrus drinks like lemonade and orange juice protect against stones because they contain citrate, which stops crystals from growing into stones. But no large-scale trials have been conducted to confirm these findings. While citrus drinks may be helpful in preventing calcium oxalate stones and uric acid stones, they might be harmful for people who form calcium phosphate stones.
In observational studies, coffee, tea, wine and orange juice have been linked to a lower risk of stones, and sugar-sweetened drinks to a higher one; none of these has been tested in randomized trials.3
What fluids should be avoided?
Grapefruit juice and dark colas have been found to increase the risk of stone formation and should be avoided by people who are prone to calcium oxalate stone formation. Although cranberry juice is often promoted as useful for preventing urinary tract infections, it contains oxalate and may be harmful to stone formers.
Miami heat and kidney stones
If you live in Miami, you already know that summer heat arrives early and stays late. South Florida sits in what urologists call the “kidney stone belt”, the southern part of the United States where heat, humidity and chronic dehydration make stones more common.
Every year, kidney stone cases rise during the late spring and summer months. As temperatures climb, we lose more fluid through sweat, our urine becomes more concentrated, and the conditions for stone formation become ideal. The equation is simple: less water intake plus more sweating means more concentrated urine and a higher risk of stone formation. In Miami, where outdoor temperatures regularly reach the 90s from May through October, many people are mildly dehydrated without realizing it, and even mild dehydration sustained over weeks can lead to stone formation.
Who is at higher risk in the summer?
- Outdoor workers — construction, landscaping, delivery, and anyone spending long hours in the heat.
- Athletes and anyone who exercises outdoors or in hot studios.
- Anyone who has already had a kidney stone.
- People who eat a high-sodium or high-protein diet.
Summer habits that help
- Drink enough water to keep your urine light yellow or clear, and more on hot or active days. Carry a water bottle and sip throughout the day.
- Lemon in your water adds citrate — but see the caution above if you form calcium phosphate stones.
- Go easy on sugary drinks and dark colas.
- Follow the salt, calcium and protein advice below.
Salt and sodium
How does salt in the diet affect kidney stone formation?
Salt is made up of sodium and chloride. The sodium in salt, when excreted by the kidneys, causes more calcium to be excreted into the urine. High concentrations of calcium in the urine combine with oxalate and phosphorus to form stones. Reducing salt intake is preferred to reducing calcium intake.
NIDDK advises adults to eat less than 2,300 milligrams (mg) of sodium a day, and the AUA guideline uses the same 2,300 mg target for people with calcium stones.13 One teaspoon of table salt holds about 2,325 mg. People taking medications — such as hydrochlorothiazide, chlorthalidone, or indapamide — to prevent stones still need to limit salt intake.
How can a person limit sodium intake?
Learning the sodium content of foods can help people control their sodium intake. Food labels provide information about sodium and other nutrients; a food with 5% or less of the daily value for sodium counts as low in sodium.1 Keeping a sodium diary can help, and when eating out, people should ask about the sodium content of foods they order.
| Foods high in sodium | Hidden sodium on labels |
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Calcium and oxalate
How does calcium in the diet affect kidney stone formation?
Calcium from food does not increase the risk of calcium oxalate stones. As NIDDK puts it, “Even though calcium sounds like it would be the cause of calcium stones, it’s not.”1 Calcium in the digestive tract binds to oxalate from food and keeps it from entering the blood, and then the urinary tract, where it can form stones. A low-calcium diet kept up for a long time can also thin the bones.
The AUA guideline advises people with calcium stones and high urine calcium to get 1,000 to 1,200 mg of calcium a day from food, ideally with meals.3 A cup of low-fat milk contains about 300 mg of calcium. Other dairy products such as yogurt and cheese are also high in calcium. For people who have lactose intolerance and must avoid dairy products, calcium-fortified juices, cereals and breads, or dairy with reduced lactose content, may be alternatives.
Calcium supplements are different: they may raise the risk of stones, and many people get enough calcium from food without them. If you do take one, take it with meals so the calcium can bind with the oxalate in food, and ask your doctor first.3
Figures from the AUA medical management guideline (2014) and NIDDK’s current page; see source 3 and source 1.
How does oxalate in the diet affect kidney stone formation?
Some of the oxalate in urine is made by the body. But eating certain foods with high levels of oxalate can increase the amount of oxalate in the urine, where it combines with calcium to form calcium oxalate stones.
How can a person limit oxalate in the urine?
Many foods and beverages contain oxalate, but only a few have been shown to increase the amount of oxalate in urine. NIDDK names five to cut back on if you have had calcium oxalate stones. Other patient guides, including the National Kidney Foundation’s, list more high-oxalate foods; published oxalate values vary with the soil, the ripeness of the food and the lab method, so no list is complete.5
| NIDDK: foods to limit | Also often listed |
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Avoiding these foods may help reduce the amount of oxalate in the urine. Eating foods containing calcium at the same meal also reduces oxalate in the urine. Many high-oxalate foods are otherwise healthy, so let a 24-hour urine test guide how strict you need to be.
How does animal protein in the diet affect kidney stone formation?
Meats and other animal proteins — such as eggs and fish — contain purines, which break down into uric acid in the urine. Foods that are especially rich in purines include organ meats, such as liver. The AUA guideline advises people with uric acid stones, or calcium stones with high urine uric acid, to limit non-dairy animal protein.3
Nondairy animal proteins may also increase the risk of calcium stones by increasing the excretion of calcium and reducing the excretion of citrate into the urine. Citrate prevents kidney stones, but the acid in animal protein reduces the citrate in urine. More fruit and vegetables help raise urine citrate.3 Beans, lentils, soy products and seeds are plant-based alternatives.1
Supplements, alcohol and weight
How do supplements affect kidney stone formation?
Supplements containing vitamin C or D may contribute to stone formation. Vitamin C is ascorbate and can be turned into oxalate by the body. Calcium supplements should be taken with meals so the calcium can bind with the oxalate in food. The B vitamins — thiamine, riboflavin, niacin, B6 and B12 — have not been shown to harm people with kidney stones, according to the National Kidney Foundation’s guide.5 A person who has a tendency to form kidney stones should consult a doctor or dietitian before taking large doses of vitamins or minerals, fish liver oils or calcium-containing supplements.
How does alcohol affect kidney stone formation?
Although drinking alcohol may promote purine production in the body, studies have not shown more stones in people who drink beer and wine. If you drink, drink in moderation.
How does a person’s weight affect kidney stone formation?
Studies have shown that being overweight increases the risk of uric acid and calcium kidney stones. Maintaining a healthy weight through healthy food choices and exercise may help reduce the risk of kidney stones; NIDDK notes that losing weight is especially important for people who have had uric acid stones.1
Can a dietitian help a person prevent kidney stones?
Yes. After a doctor has completed an evaluation and determined the causes of a person’s stones, a dietitian can help a person plan meals that lower the risk of forming stones. People who form stones can ask their doctor or nurse to help them find a dietitian who specializes in kidney stone prevention or renal, or kidney, nutrition. Sometimes diet alone is enough to prevent new stones; other times medication is needed as well.
Questions to ask the doctor
- What kind of kidney stone do I have?
- How much fluid should I drink every day?
- How much protein and what type of protein should I eat every day?
- Am I getting enough calcium in my diet?
- Can you recommend a dietitian who specializes in kidney stone prevention or renal nutrition?
- Do I need to take medication to prevent kidney stones?
Sources
Text drawn from NIDDK publications is a U.S. government work and not copyrighted. Figures checked October 2026.
- National Institute of Diabetes and Digestive and Kidney Diseases. Eating, Diet, & Nutrition for Kidney Stones.
- National Institute of Diabetes and Digestive and Kidney Diseases. Diet for Kidney Stone Prevention.
- Pearle MS, Goldfarb DS, Assimos DG, et al. Medical Management of Kidney Stones: AUA Guideline.
- American Urological Association. American Urological Association Releases Guideline on Medical Management of Kidney Stones.
- National Kidney Foundation. Diet and Kidney Stones (patient guide).
