Kidney stones can be extremely painful, but knowing the right foods to eat and avoid can play a significant role in preventing them.
Kidneys detox the body by removing excess liquids and waste from the foods you eat. But when you consume an unhealthy diet, you add to your kidneys’ workload – and challenge their ability to get their job done. Certain foods and drinks can strain the kidneys or increase risks for health complications like kidney stones.
The pain of kidney stones can be excruciating, but your diet can play a significant role in preventing them. If you have a history of kidney stones or want to reduce your risk of developing one in the future, learning about the right foods for kidney health is key.
What Causes Kidney Stones
Kidneys eliminate waste through urine production – one of their essential functions. Yet buildups or blockages can interfere with this process. Kidney stones are hard, often painful, chemical blockages in the kidneys. Depending on their type and size, they can sit in the kidneys or make their way through the urinary tract to be excreted when you go to the bathroom – or ‘pass’ the stone, which can be very painful.
About 10% of people will have a kidney stone at some point in their life, according to the National Kidney Foundation.
People’s risks of developing kidney stones can depend on several factors, including:
Personal or family health history of kidney stones.
Obesity.
Diabetes.
Kidney conditions.
Dehydration.
A diet high in sodium or an otherwise unhealthy diet.
Stones can be caused by a buildup of various chemicals, including calcium, oxalate, urate, cystine, xanthine and phosphate. Due to this variety, a diet that helps eliminate one kind of kidney stone may fall short in fighting off another, says Dr. Alice Wei, officer of the chief medical office at Strive Health in New York City. To help best individualize your dietary approach, Wei recommends seeing a nephrologist or a urologist for a stone analysis.
Types of kidney stones:
Calcium oxalate stones.
Uric acid stones.
Struvite stones.
Cystine stones.
The most common type of kidney stone is a calcium oxalate stone, which form when calcium combines with oxalate in your urine. Oxalate is a substance found in many foods, particularly in plant-based foods. Eighty percent of kidney stones are formed by calcium oxalate. Causes of calcium oxalate stones include a diet high in oxalate and not consuming enough calcium or fluid.
Uric acid stones occur when your urine is too acidic. For instance, you may have lost fluid due to dehydration or diarrhea, says registered dietitian Kimberly Barton of Bair Aesthetics in Columbus, Ohio. A diet that is high in protein also may lead to uric acid stones. Uric acid stones make up about 9% of the stones that occur in people, Semins says.
Struvite stones are commonly linked to urinary tract infections. They form when ammonia builds up in your urine.
Cystine stones are the least common type of kidney stone, and it’s formed by a genetic disorder called cystinuria. A person with cystinuria leaks a substance called cystine in their urine. When there’s too much cystine, it can lead to the formation of kidney stones. An estimated 1 in 7,000 people have cystinuria.
Kidney stones also can be associated with the use of certain medications, infections and medical conditions such as inflammatory bowel disease.
How to Prevent Kidney Stones and Improve Kidney Health
A healthy diet can reduce your risk for developing a kidney stone, and help you pass one if one forms. However, diet alone may not prevent a stone from developing or help pass a stone, for everyone’s individual health factors and circumstantial risks can come into play.
Still, for any type of kidney stone, drinking more water and consuming less salt can help set your foundation for kidney stone prevention. After that, the below tips can aide in preventing calcium oxalate stones – the most common kidney stones. If you currently have a stone and are not sure what type it is, it’s important to go to the doctor for a stone assessment.
6 tips to prevent kidney stones:
1. Drink more water
The first mainstay of kidney stone prevention is adequate hydration, Wei says.
“You need to be drinking enough water,” Wei adds. “If you can dilute the urine so that the concentration of calcium or oxalate or uric acid does not reach that tipping point where a stone can form, you’re reducing your risk.”
Dilution can both protect against buildup and assist in washing a stone through the urinary tract if it has formed. You can retroactively check if you’re hydrated, by taking a peek at the color of your urine after you use the bathroom.
“Assuming that your toilet bowl is white, if you see very pale, straw-colored urine, that’s a good sign,” Wei says.
You can also plan ahead, by setting a daily hydration goal. Wei encourages drinking at least 2 liters of water per day. While this can seem like a lot, especially if you’re not used to it, it’s worth it. “If you can drink that amount every single day, that’s a good starting point.” Of water, she specifies – “not Coke, not coffee or tea, just water.”
Sports drinks don’t count either, she adds. Beverages like Gatorade contain a significant amount of salt – an infamous kidney stone agitator.
2. Eat less salt
Eating too much salt can increase your risk for developing a kidney stone.
“Sodium actually causes the urinary environment to be more favorable towards stone formation,” Wei says. “So, if you can limit the amount of salt intake and increase the amount of water intake that would help tremendously.”
Sodium is a kidney stone culprit because it can increase the amount of calcium in your urine. About 80% of kidney stones are calcium oxalate stones, the most common type of stone.
Wei recommends sticking to a maximum of two grams, or 2,000 milligrams, of sodium per day. This is slightly lower than the U.S. recommended daily allowance, or RDA, of 2.3 grams of sodium per day for people older than 14, and the same as that set by the World Health Organization.
Refraining from over-salting your food at the dinner table is one way to reduce sodium intake. But that’s just one piece of the puzzle. Canned and frozen foods often contain high amounts of sodium used for preservatives, says Nadine Gregory, a registered dietitian and general manager of Food & Nutrition for Sodexo at Sharp Healthcare in San Diego, California.
Gregory recommends rinsing canned foods before preparation and buying fresh foods with low sodium content when possible.
3. Eat more fiber
Eating foods high in fiber can help push solid waste out of the body. This can reduce the chances of buildup and reinforce a healthy metabolism.
“Fiber will work wonders to help you stay regular and keep things moving out of your body,” Gregory says.
Complex carbohydrates like fresh fruits and vegetables that are high in fiber should be go-to’s, she adds.
4. Put down the protein
Despite the Western world’s idolization of high-protein diets, overdoing it can have negative health impacts on the kidneys.
“The Western diet very much emphasizes protein, especially with diets like the Atkins diet and the Keto diet. But high protein intake can also increase your risk of kidney stones,” Wei says. “I tell patients to try to stick to balance and moderation.”
The RDA for adult protein consumption is about 0.8 grams of protein per pound of body weight. While this is just a recommendation, Gregory says it’s a good one to follow because our body can only make use of so much protein at once.
“Once your body takes what it needs, whatever is left is in line waiting to be processed out,” Gregory explains.
This can include excess nutrients like phosphorus, which requires filtration from the kidneys. Depending on how your protein is seasoned, it can also include high amounts of sodium, which can increase the risk for kidney stones, Gregory explains.
Phosphorus alone shouldn’t increase your risks for stones, so you don’t have to worry about it unless you are on a different type of medically recommended diet, Gregory adds. For instance, too much phosphorus can be harmful for people with kidney disease, as they are unable to remove phosphorus from the blood. If you have kidney disease, you will likely need to follow a more strict diet recommended to you by a medical professional (which this article does not cover).
“Your body is doing its best to make it through the rush of nutrients,” Gregory says. “A balanced diet can help ensure that your kidneys aren’t always backed up and fatigued, trying to sort through high amounts of waste.”
High protein intake can make the urine more acidic, which is favorable for kidney stones. Further, it can decrease levels of urinary citrate, a chemical that can help fight against kidney stones by binding to urinary calcium. A high-protein diet is associated with uric acid stones in particular.
5. Avoid excess oxalate
The most common type of kidney stone is the calcium oxalate stone. Derived from the compounds calcium and oxalate, high oxalate content can increase risks for stones.
Oxalate is an organic compound found in several plants, many of which are healthy and nutritious. But excess consumption, especially without adequate hydration, can be dangerous.
According to research, oxalate can take several days to be cleared from the gut and too much of it can cause a crystalized buildup in the urinary tract, which may play a role in kidney stone growth. High oxalate intake may also increase your risk for kidney disease.
Some high-oxalate foods include:
Beets.
Chocolate.
Nuts.
Nut butters.
Rhubarb.
Spinach.
Carambola, or star fruit.
Wei has family in Taiwan, where carambola, or star fruit, is commonly consumed as juice. She says that the frequent consumption of carambola – especially in high-temperature seasons when people may be dehydrated from sweat – has at times led to high local incidences of calcium oxalate stones.
“Periodically, you’ll hear public service announcements cautioning people against eating or drinking too much of this star fruit, or carambola, juice,” Wei adds.
Some studies suggest that soaking or cooking high-oxalate foods can reduce the oxalate content before eating. However, as with most foods, consuming oxalate-containing plants is healthy in moderation, and people do not typically need to avoid eating these if not at risk for a kidney stone, Wei says.
6. Keep up the calcium
Surprisingly, high calcium intake does not necessarily increase risks for these stones – although researchers used to think this was the case. Now, they recommend keeping up your calcium intake, following recommended daily values for your age group.
That’s because adequate calcium intake can balance out oxalate levels, Wei says. Dietary calcium binds to dietary oxalate in the gut, and two can be eliminated together in the stool when you go to the bathroom, she explains. If you don’t consume enough calcium, however, there is “increased oxalate absorption through the gut,” and a higher likelihood of oxalate being eliminated through the urine, not stool. This can increase the risk of a calcium oxalate kidney stone.
5 Best Foods to Prevent Kidney Stones
Besides increasing water and decreasing sodium intake, Wei says “there is not a one size fits all diet for reducing risk of kidney stones.” That’s because different types of stones have different trigger foods and remedies – and you have different dietary needs than your neighbor too, she explains.
If you have a current kidney stone, be sure to visit your doctor for a stone analysis so that you can be sure that diet is best for you. If you have a history of kidney stones, you may want to take note of what type of stone you had in the past and eat accordingly.
However, for the most common kidney stones – calcium oxalate stones – there are some go-to foods and juices that may help with prevention.
1. Lemon juice
To pass or prevent a calcium oxalate stone, Wei recommends drinking lemon juice diluted in water.
She explains that lemon juice helps with kidney stone prevention as it can increase levels of urine citrate. Citrate can bind to calcium in the urine to block stone formation. The citrate in lemon juice also “increases urinary pH which is an unfavorable environment for most urinary stones,” Wei says.
Since you should already be amping up your hydration, you may want to start by adding a squeeze or two of water to your drinking glass, jug or bottle.
2. Grapefruit
Grapefruit is high in citrate. Like lemons, the fruit or juice from the fruit can help create an unfavorable environment for kidney stones.
3. Oranges
Oranges are also high in citrate, so eating or drinking them can be helpful in preventing kidney stones. Oranges are also high in potassium, which can aid in kidney stone prevention. Studies show that potassium can help prevent kidney stones by decreasing urinary excretion of calcium and uric acid, among other mechanisms. This is thought to reduce the risks of calcium oxalate and uric acid stone formations.
4. Potassium-rich foods
Foods that are good sources of potassium may aid in kidney stone prevention. Examples include:
Bananas.
Honeydew.
Cantaloupe.
Avocados.
Raisins.
Chicken and salmon are also good sources of protein that are high in potassium.
5. Cruciferous vegetables
In addition to being a good source of potassium, broccoli does not contain oxalates. Due to this, it can fight against calcium loss and prevent kidney stones from forming. Similarly, kale and Brussels sprouts don’t contain oxalates and are high in potassium.
Medical Interventions for Kidney Stones
It doesn’t hurt to check in with your doctor about a kidney stone (especially if it’s hurting). While a doctor may recommend dietary interventions like the ones above, they may also be able to provide you with a more targeted solution to meet your individual needs. They may have supplement suggestions too.
Depending on how much pain you’re experiencing, your doctor could prescribe or guide you toward pain medications to make things more comfortable. They could also prescribe you water pills or a diuretic to help pass the stone.
If the stone is too large to pass with diet and over-the-counter medications, your doctor may schedule a procedure like a ureteroscopy, shockwave lithotripsy, percutaneous nephrolithotomy or, on rare occasions, open stone surgery. These are all procedures that use various methods of breaking up and taking out kidney stones from your body. The last method, open stone surgery, is the least common and most invasive.
Warning: Because kidneys work closely with the urinary tract, some people think that urinary tract infection, or UTI, prevention methods can translate to kidney stone prevention. Unfortunately, this isn’t always true. Cranberry juice, a go-to UTI blocker, is high in oxalate and can increase risks of forming kidney stones. So steer clear.
Preventive Medications for Kidney Stones (When to See Your Doctor)
If you have a history of kidney stones, your doctor may also be able to prescribe you medications for prevention. Some potential options include:
Alpha blockers
Alpha blockers help relax muscles in the ureters, reducing pain if a kidney stone returns and increasing your body’s ability to pass the stone on its own.
Potassium citrate
Potassium citrate can work against kidney stones by reducing the risk that they form, or stopping them from growing too large if they occur.
Thiazide diuretic
Thiazide diuretics can reduce the amount of calcium in the urine. This can reduce your risk of kidney stones. (Remember, urinary calcium levels are not necessarily influenced by how much dietary calcium you eat, so don’t cut that out if you are at risk.)
Allopurinol
Allopurinol can reduce the amount of uric acid your body produces, decreasing your risk for stones. This isn’t always necessary, especially if you are mindful of your protein intake to begin with. It can be more helpful for people who eat high-protein diets or who are diagnosed with gout, a type of inflammatory arthritis caused by excess uric acid, according to NYU Langone Health.
Getting a health professional’s input can help guide your prevention or recovery.
The Take Home
When it comes to a kidney-supportive diet, balance is key. If your goal is kidney stone prevention, being mindful to increase hydration and decrease sodium intake should be your first and second in command. From there, a combination of following the above tips, listening to your body and talking with a health professional can help devise a supportive diet.
“No food is ever totally off-limits. It’s all about moderation,” Gregory says.
If you are in need of more guidance, she adds that “whole fresh foods that you prepare are always the best bet,” and so long as you are mindful of oxalate and sodium content, countless fruits and vegetables can benefit your health and contribute to a kidney-healthy diet.
Check in with your doctor if you feel that you have developed a kidney stone or if you are at risk for a more serious complication like kidney disease, in which case some foods may be off limits. If you have kidney disease or failure, you will need to follow an individualized meal plan.
If you do not have an individualized meal plan, focusing on whole, fresh foods can ward off kidney complications and a slew of other health conditions that are brought on by a bad diet.
“If you experience any decline in kidney function, adequate nutrition is key as you are at greater risk for malnutrition,” Gregory says. She encourages working closely with your physician or dietitian to individualize a meal plan.
