Diet for Kidney 

Stone Prevention 

National Kidney and Urologic Diseases Information Clearinghouse 

U.S. Department 

of Health and 

Human Services 

NATIONAL 

INSTITUTES 

OF HEALTH 

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. 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 

from bone may also play a role in kidney 

stone formation. 

•	 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. 

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. People who have had a kidney 

stone should drink enough water and other 

fluids to produce at least 2 quarts of urine a 

day. 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. Drinking enough 

water helps keep urine diluted and flushes 

away materials that might form stones and is 

the most important thing a person can do to 

prevent 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. 

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. 

Coffee and tea can add to a person’s total 

fluid intake and have been shown to reduce 

the risk of stone formation, but they do 

contain oxalate. Moderate intake of beer 

and wine may also protect against stone 

formation. 

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. 

2 Diet for Kidney Stone Prevention 
 

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. 

The U.S. recommended daily allowance 

(RDA) of sodium is 2,400 milligrams (mg), 

but Americans’ intake averages 3,300 mg, 

according to the National Heart, Lung, and 

Blood Institute. The risk of kidney stones 

increases with increased daily sodium consumption. Limiting salt to the U.S. RDA 

goal of 2,400 mg is an important step for 

people who form calcium oxalate or calcium phosphate stones. 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. Keeping a 

sodium diary can help a person limit sodium 

intake to 2,400 mg. When eating out, people 

should ask about the sodium content of 

foods they order. 

Some foods have such large amounts of 

sodium that a single serving provides a major 

portion of the daily allowance. Foods that 

contain high levels of sodium include 

•	 hot dogs 

•	 canned soups and vegetables 

•	 processed frozen foods 

•	 luncheon meats 

•	 fast food 

People who are trying to limit their sodium 

intake should check labels for ingredients 

and hidden sodium, such as 

•	 monosodium glutamate (MSG) 

•	 sodium bicarbonate, the chemical name 

for baking soda 

•	 baking powder, which contains sodium 

bicarbonate and other chemicals 

•	 disodium phosphate 

•	 sodium alginate 

•	 sodium nitrate or nitrite 

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. People who form uric 

acid stones should limit their meat consumption to 6 ounces each day. 

3 Diet for Kidney Stone Prevention 
 

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. 

How does calcium in the 

diet affect kidney stone 

formation? 

Calcium from food does not increase the 

risk of calcium oxalate stones. 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. People who form calcium oxalate 

stones should include 800 mg of calcium in 

their diet every day, not only for kidney 

stone prevention but also to maintain bone 

density. A cup of low-fat milk contains 

300 mg of calcium. Other dairy products 

such as yogurt are also high in calcium. For 

people who have lactose intolerance and 

must avoid dairy products, orange juice 

fortified with calcium or dairy with reduced 

lactose content may be alternatives. Some 

studies indicate that calcium supplements 

increase the risk of calcium oxalate stone formation. Researchers theorize that calcium 

must be taken at the same time as dietary 

oxalate to protect against stone formation. 

Calcium supplements taken with meals may 

have the same protective effect as dietary 

calcium. 

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: 

•	 spinach 

•	 rhubarb 

•	 nuts 

•	 wheat bran 

Avoiding these foods may help reduce the 

amount of oxalate in the urine. Eating foods 

containing calcium also reduces oxalate 

in the urine. Calcium binds oxalate in the 

digestive tract so it is not excreted into the 

urine. 

4 Diet for Kidney Stone Prevention 
 

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. People should have no more 

than two drinks—two 12-ounce servings of 

beer or two 5-ounce servings of wine or two 

1.5-ounce servings of hard liquor—a day. 

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. Doctors recommend no more than 

500 milligrams each day for people who have 

had kidney stones. Calcium supplements 

should be taken with meals so the calcium 

can bind with the oxalate in food. A person 

who has a tendency to form kidney stones 

should consult a doctor or dietitian before 

taking large doses of vitamins or minerals. 

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. Scientists don’t know whether 

losing weight by itself can reduce the risk of 

kidney stones. Maintaining a healthy weight 

through healthy food choices and exercise 

may help reduce the risk of kidney stones. 

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. 

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?
 

5 Diet for Kidney Stone Prevention 
 

Points to Remember 

•	 Diet is one of several factors that 

can promote or inhibit kidney stone 

formation. 

•	 Different kinds of kidney stones 

require different prevention diets. 

•	 Drinking water and other fluids is 

the most important thing a person 

can do to prevent kidney stones. 

•	 People who have had a kidney stone 

should drink enough water and 

other fluids to make at least 2 quarts 

of urine each day. 

•	 Diets high in salt, or sodium, can 

increase the excretion of calcium 

into the urine and thus increase the 

risk of calcium containing kidney 

stones. Reducing salt intake is preferred to reducing calcium intake. 

•	 Foods rich in animal proteins—such 

as meat, eggs, and fish—contain 

purines and can increase the risk of 

uric acid stones and calcium stones. 

•	 Calcium from food can help prevent 

kidney stone formation and help 

maintain bone density. 

•	 Avoiding foods rich in oxalates, such 

as spinach and rhubarb, may help 

prevent calcium oxalate stones. 

•	 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. 

Hope through Research 

The Division of Kidney, Urologic, and 

Hematologic Diseases of the National Institute of Diabetes and Digestive and Kidney 

Diseases (NIDDK) funds research on the 

causes, treatments, and prevention of kidney 

stones. The NIDDK is part of the National 

Institutes of Health in Bethesda, MD. 

NIDDK-sponsored researchers are working 

to answer the following questions: 

•	 What dietary factors promote or protect 

against stone formation? 

•	 How can doctors predict, or screen, 


those at risk for getting stones?
 

•	 Do genes play a role in stone 


formation?
 

•	 What is the natural substance(s) found 

in urine that blocks stone formation? 

Participants in clinical trials can play a more 

active role in their own health care, gain 

access to new research treatments before 

they are widely available, and help others by 

contributing to medical research. For information about current studies, visit 

www.ClinicalTrials.gov. 

6 Diet for Kidney Stone Prevention 
7 Diet for Kidney Stone Prevention

For More Information 

American Urological Association Foundation 

1000 Corporate Boulevard 

Linthicum, MD 21090 

Phone: 1–866–RING–AUA (1–866–746–4282) 

 or 410–689–3700 

Email: patienteducation@auafoundation.org 

Internet: www.auafoundation.org 

 www.UrologyHealth.org

National Kidney Foundation

30 East 33rd Street 

New York, NY 10016 

Phone: 1–800–622–9010 or 212–889–2210 

Internet: www.kidney.org

Oxalosis and Hyperoxaluria Foundation

201 East 19th Street, Suite 12E 

New York, NY 10003 

Phone: 1–800–OHF–8699 (1–800–643–8699) 

 or 212–777–0470 

Fax: 212–777–0471 

Email: execdirector@ohf.org 

Internet: www.ohf.org

Acknowledgments

Publications produced by the Clearinghouse 

are carefully reviewed by both NIDDK scientists and outside experts. This fact sheet was 

reviewed by Gary Curhan, M.D., Harvard 

Medical School, and David Goldfarb, M.D., 

New York University School of Medicine.

You may also find additional information about this 

topic by visiting MedlinePlus at www.medlineplus.gov.

This publication may contain information about 

medications. When prepared, this publication 

included the most current information available. 

For updates or for questions about any medications, 

contact the U.S. Food and Drug Administration 

toll-free at 1–888–INFO–FDA (1–888–463–6332) 

or visit www.fda.gov. Consult your doctor for more 

information.
National Kidney and 

Urologic Diseases 

Information Clearinghouse 

3 Information Way 

Bethesda, MD 20892–3580 

Phone: 1–800–891–5390 

TTY: 1–866–569–1162 

Fax: 703–738–4929 

Email: nkudic@info.niddk.nih.gov 

Internet: www.kidney.niddk.nih.gov 

The National Kidney and Urologic Diseases 

Information Clearinghouse (NKUDIC) 

is a service of the National Institute of 

Diabetes and Digestive and Kidney Diseases 

(NIDDK). The NIDDK is part of the 

National Institutes of Health of the U.S. 

Department of Health and Human Services. 

Established in 1987, the Clearinghouse 

provides information about diseases of the 

kidneys and urologic system to people with 

kidney and urologic disorders and to their 

families, health care professionals, and the 

public. The NKUDIC answers inquiries, 

develops and distributes publications, and 

works closely with professional and patient 

organizations and Government agencies 

to coordinate resources about kidney and 

urologic diseases. 

This publication is not copyrighted. The Clearinghouse 

encourages users of this fact sheet to duplicate and 

distribute as many copies as desired. 

This fact sheet is also available at 

www.kidney.niddk.nih.gov. 

U.S. DEPARTMENT OF HEALTH 

AND HUMAN SERVICES 

National Institutes of Health 

NIH Publication No. 09–6425 

May 2009