Diet and Kidney Stones

If you have kidney stones, you may need to follow a special diet. First, your doctor will run tests to find out what type of stones you form. From these, the doctor can determine which diet changes may be right for you. A registered dietitian can help you make the necessary changes in your diet.

What is a kidney stone?

A kidney stone is a hard mass that forms from crystals in the urine. In most people, natural chemicals in the urine stop stones from forming.

Are all kidney stones the same?

No. The most common types of kidney stones are made from calcium and oxalate. Individual treatment for kidney stones depends on the type of kidney stones that are formed.

Is there a diet I can follow to prevent me from having more kidney stones?

Sometimes following a special diet may be enough to prevent you from forming more kidney stones. Other times, medications, in addition to a special diet, may be needed.  Please note that not all dietary recommendations benefit all types of stone formers.

What kind of diet will I have to follow?

You may be asked to make changes to the amount of salt (sodium), calcium, oxalate, protein, citrate, potassium and fluid in your diet. A registered dietitian can help you with making these changes.

My doctor told me to drink a lot of fluids. How much is "a lot"? Does it matter what kind of fluid I drink?

Staying well hydrated by drinking enough water is one of the best measures you can take to avoid kidney stones. To lessen your risk of forming a new stone, it is very important that you drink at least three quarts (12 cups) of fluid throughout the day. In hotter weather, you may need to drink more to make up for fluid loss from sweating. This will help keep your urine less concentrated. Less concentrated urine reduces the risk of stone formation. Most of the fluid you drink should be water. Try to drink a glass of water before bed and if you wake during the night to use the bathroom, drink another glass before going back to bed.

I had a calcium stone. What type of diet should I follow? Will I have to avoid high calcium foods?

Calcium is not the enemy. If you have high calcium in the urine then sodium reduction is helpful for stone prevention. Instead of reducing your calcium intake, focus on limiting the sodium in your diet and pair calcium-rich foods with oxalate-rich foods. Extra sodium causes you to lose more calcium in your urine, putting you at risk for developing another stone. Your doctor will probably advise you to limit sodium to 2,000 milligrams each day. There are many sources of "hidden" sodium such as canned or commercially processed foods as well as restaurant-prepared and fast foods. A dietitian help you understand food labels and make changes in the amount of sodium that you eat. If you do not have high calcium in the urine then for stone reduction you might be better off focusing on other dietary changes. Your doctor or registered dietitian can help determine if you need more or less calcium and help you plan a diet that is healthful.

I had an oxalate stone. What type of diet should I follow? Do I need to avoid foods high in oxalate?

Calcium oxalate kidney stones are the leading type of kidney stones. Oxalate is naturally found in many foods, including fruits and vegetables, nuts and seeds, grains, legumes, and even chocolate and tea. Some examples of foods that contain high levels of oxalate include: peanuts, rhubarb, spinach, beets, chocolate and sweet potatoes. The oxalate content of food can vary due to differences in such things as soil quality and state of ripeness. There may be variation in published data, too, as different methods may be used to determine the oxalate content of food.

Some research suggests that limiting high oxalate foods may help reduce your chance of forming another oxalate stone. However, many high oxalate foods are healthful so it is wise to not overly restrict your diet if not necessary. Most kidney stones are formed when oxalate binds to calcium while urine is produced by the kidneys. New research indicates that eating and drinking calcium and oxalate-rich foods together during a meal is a better approach than limiting oxalate entirely because oxalate and calcium are more likely to bind to one another in the stomach and intestines before the kidneys begin processing, making it less likely that kidney stones will form.

Talk with your doctor about how strictly you need to avoid oxalate-containing foods.

I had a uric acid stone. What does that mean? What type of diet should I follow?

Another common type of kidney stones is uric acid stones. Meat, seafood and most high-protein foods have high concentrations of a natural chemical compound known as purines. High purine intake leads to a higher production of uric acid and in turn makes the urine more acidic. The high acid concentration of the urine makes it easier for uric acid stones to form.

To prevent uric acid stones, cut down on high-purine foods which include: chicken, fish, seafood such as lobster and shrimp, organ meats such as liver, tongue, and sweetbreads, anchovies, sardines, bacon, beef, cauliflower, codfish, ham, veal and venison.

Follow a healthy diet that contains mostly vegetables and fruits, whole grains, and low fat dairy products. Limit sugar-sweetened foods and drinks, especially those that contain high fructose corn syrup. Additionally, limit alcohol and avoid crash diets because they can make the urine more acid, which makes it harder for uric acid to dissolve.

You should also be sure to drink at least three quarts (12 cups) of water a day to help reduce the risk for stone formation. Making these healthy lifestyle changes can also help reduce your risk for developing gout because high uric acid is a leading risk factor for gout.

Is there anything else I can do with my diet to help prevent kidney stones?

Reducing the amount of animal protein may help. Sources of animal protein include beef, chicken, pork, fish and eggs. Most people need only four to six ounces of high protein foods and three servings of milk or cheese a day. Check with your doctor or dietitian to be sure your protein intake is enough, but not too much.

Chronic kidney stones are often treated with potassium citrate. Studies have shown that limeade, lemonade and other fruits and juices high in natural citrate may offer similar stone-preventing benefits. It is believed that citrate in the urine may prevent the calcium from binding with other constituents that lead to stones. Also, some evidence suggests that citrate may prevent crystals that are already present from binding with each other, thus preventing them from getting bigger. Please note that juices made from actual limes and lemons contain higher levels of citrate and beware of the sugar content in juices, because this can increase kidney stone risk.

Will it help/hurt me to take a vitamin or mineral supplement?

The B vitamins (which include thiamine, riboflavin, niacin, B6 and B12) have not been shown to be harmful to people with kidney stones. In fact, some studies have shown that B6 may actually help people with high urine oxalate. However, check with your doctor or dietitian for advice on the use of vitamin C, vitamin D, fish liver oils or mineral supplements containing calcium since some supplements can increase the chances of stone formation in some people.

Last updated August 2013

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©2014 National Kidney Foundation. All rights reserved. This material does not constitute medical advice. It is intended for informational purposes only. Please consult a physician for specific treatment recommendations.