Kidney Stones Diet and Prevention

Kidney stones are small, hard pieces of material that can form in your kidneys. They are made from substances in your urine (pee). A stone may stay in the kidney or move through the urinary tract, which includes the kidneys, ureters, bladder, and urethra.

Urine contains minerals, salts, and other substances. When there is too much of certain substances and not enough fluid, crystals can form. Over time, these crystals can grow into a kidney stone.

Diet and nutrition can play an important role in kidney stone prevention. There is no single diet plan that is right for everyone with kidney stones. The best plan depends on the type of stone you have, your urine and blood test results, your medicines, and your overall health.

A doctor, registered dietitian, or registered kidney dietitian can help you understand which changes are right for you.

Your kidney stone prevention plan should be based on the type of stone you have, your test results, and your health needs. Some common steps may include:

• Drink enough water to help keep your urine diluted.
• Limit sodium.
• Get the right amount of calcium from food.
• Limit high-oxalate foods only if your care team recommends it.
• Avoid eating large amounts of animal protein.
• Ask before taking vitamins, minerals, or herbal supplements.

Do not cut out food groups or start a strict diet on your own. A diet change that helps one type of stone may not help another.

Drinking enough water every day is one of the best ways to help prevent kidney stones. Water helps keep your urine diluted. This makes it harder for minerals to stick together and form stones.

How much fluid you may need

Many people who have had kidney stones are advised to make at least 2 liters, or about 8 cups, of urine each day. This often requires drinking more than 8 cups of fluid a day. Your doctor or dietitian can help you set a goal based on your health, activity level, and climate.

Water is the best choice.

Limit drinks with a lot of added sugar, such as regular soda and sweetened tea. Ask your doctor or dietitian whether there are other drinks you should limit based on your stone type and medicines.

When you may need more water

You lose water when you sweat. If you do not replace that fluid, your body makes less urine and the urine becomes more concentrated. This can make kidney stones more likely to form.

You may need more water when you:

• Exercise
• Work outdoors
• Spend time in hot weather
• Use a sauna
• Do hot yoga

Drink water before, during, and after activity. Take breaks when needed.

Check your urine color

Urine that is light yellow or almost clear may be a sign that you are drinking enough. Dark yellow urine may mean you need more fluid.

If you have kidney disease, heart disease, swelling, or have been told to limit how much you drink, ask your doctor how much fluid is right for you.

Sodium is found in salt. Eating too much sodium can cause more calcium to leave your body through your urine. This can raise your chance of forming another stone.

Foods that may be high in sodium include:

• Fast food and restaurant meals
• Canned soups
• Packaged or frozen meals
• Deli and processed meats
• Chips and salty snacks
• Sauces, seasonings, and condiments with a lot of sodium

Choosing more fresh foods and lower-sodium options can help lower your stone risk. It can also help manage blood pressure.

Compare Nutrition Facts labels and choose foods with less sodium when possible.

Do not stop eating foods with calcium unless your doctor tells you to. Calcium is important for your bones and overall health. Eating too little calcium can raise the risk of calcium oxalate stones.

When you eat calcium and oxalate at the same meal, they can bind together in your digestive system. This may keep more oxalate from reaching your kidneys.

Calcium-rich foods include:

• Milk
• Yogurt
• Cheese
• Calcium-fortified foods, if recommended by your care team

The amount of calcium you need depends on your age, health, and diet. Your doctor or dietitian can help you set a daily goal.

Calcium supplements may affect stone risk differently than calcium from food. Ask your doctor or dietitian before taking them.

Oxalate is a natural substance found in many foods. Not everyone with kidney stones needs to limit oxalate.

If you form calcium oxalate stones, your doctor or dietitian may tell you to limit some foods that are high in oxalate. Your plan should be based on your own test results.

Some foods with higher amounts of oxalate may include:

• Spinach
• Rhubarb
• Beets
• Swiss chard
• Sweet potatoes
• Peanuts
• Chocolate
• Tea

You may not need to avoid all foods with oxalate. Your doctor or dietitian can help you know which foods, if any, you should limit.

Eating calcium-rich foods with meals may also help. See Get the right amount of calcium above.

Eating large amounts of animal protein may raise the risk of some types of kidney stones. Animal protein includes meat, poultry, seafood, and eggs.

You may not need to avoid these foods. Some animal proteins can raise uric acid and make urine more acidic. Your doctor or dietitian may recommend smaller portions or different protein choices, including some plant-based proteins.

There is no single diet plan that prevents kidney stones for everyone. The best plan depends on the type of stone you have, your urine test results, your health history, and your medicines.  Testing a passed kidney stone, blood, or urine can help your care team understand why stones are forming. Your prevention plan may depend on the results.

These tests can help your care team know what changes may help prevent another stone.

Calcium oxalate stones

Calcium oxalate stones are the most common type of kidney stone. If you form these stones, your care team may recommend that you:

• Drink more water
• Limit sodium
• Get the right amount of calcium
• Limit certain high-oxalate foods, if needed

Your diet plan should be based on your test results.

Uric acid stones

Uric acid stones  can form when there is too much uric acid in the urine. Some foods can raise uric acid levels. These foods are often high in purines. Purines are natural substances found in some foods, especially certain animal proteins.

If you form uric acid stones, your doctor or dietitian may tell you to limit:

• Red meat and organ meats, such as liver
• Some seafood, including shellfish, sardines, and anchovies
• Meat-based gravies
• Alcohol, especially beer
• Drinks with a lot of added sugar or high fructose corn syrup

Your doctor or dietitian may suggest eating more fruits, vegetables, whole grains, and low-fat dairy foods. For some people, this may help make the urine less acidic and lower the chance of uric acid stones.

Some people may also need medicine.

Struvite stones

Struvite stones are usually linked to urinary tract infections. They are not usually caused by diet alone.

If you form struvite stones, your care plan may focus on treating or preventing infections. Your doctor may also suggest drinking enough fluids to help keep urine flowing.

Cystine stones

Cystine stones are rare. They are caused by an inherited condition that allows too much cystine to build up in the urine.

If you form cystine stones, your doctor may suggest drinking more fluids to help dilute your urine. Some people may also need medicines or a special eating plan.

Before starting any vitamin, mineral, or herbal supplement, talk with your doctor or dietitian. Bring a list of everything you take, including over-the-counter supplements. Your care team can help you understand what may be safe for you.

Vitamins and herbal supplements can affect people in different ways. Some may be safe for many people, but others may raise the chance of kidney stones in some people.

This can depend on:

• The type of kidney stone you have had
• Your urine test results
• Your kidney function
• Your other health conditions
• The dose of the supplement
• Other medicines or supplements you take

Some supplements may need extra caution, including:

• Vitamin C
• Vitamin D
• Calcium supplements
• Fish liver oils
• Mineral supplements that contain calcium

B vitamins, such as thiamine, riboflavin, niacin, B6, and B12, have not been shown to be harmful for most people with kidney stones. Some research has looked at vitamin B6 and urine oxalate levels, but this does not mean everyone with kidney stones should take it.

Ask before making big diet changes

Do not start a strict diet or cut out major food groups on your own. Some diet changes can help one type of kidney stone but may not help another type.

Ask your doctor or dietitian what diet plan is best for your type of kidney stone.

Key diet steps that may help prevent kidney stones

Your kidney stone prevention plan should be based on the type of stone you have, your urine test results, and your overall health. Some common diet steps may include:

• Drink enough fluids each day. Water is the best choice. Drinking enough fluid helps keep your urine diluted, which can lower the chance of stones forming.
• Limit sodium. Eating too much sodium can increase calcium in the urine, which may raise the chance of calcium stones.
• Eat the right amount of calcium. Do not cut out calcium unless your doctor tells you to. For some people, eating calcium-rich foods with meals may help lower the risk of calcium oxalate stones.
• Limit high-oxalate foods if needed. If you form calcium oxalate stones, your doctor or dietitian may suggest limiting foods that are high in oxalate, such as spinach, rhubarb, beets, nuts, chocolate, tea, or wheat bran.
• Do not overdo animal protein. Eating a lot of animal protein may raise the risk of some types of kidney stones, especially uric acid stones. 
• Ask before taking supplements. Some supplements, such as vitamin C, vitamin D, calcium, or mineral supplements, may affect kidney stone risk for some people.