4 ways to prevent kidney stones
- To prevent kidney stones, you should drink lots of water, get more calcium, cut back on sodium, and be careful with oxalate-rich foods.
- There are a few different types of kidney stones, and depending on which type you're at risk for, your doctor may recommend specific prevention methods.
- This article was medically reviewed by S. Adam Ramin, MD, urologic surgeon and medical director of Urology Cancer Specialists in Los Angeles, California.
About 1 in 11 Americans will get a kidney stone at some point in their life. Kidney stones are solid masses that look like tiny pieces of gravel. They form in your kidneys from minerals found in urine.
There are four types of kidney stones:
- Calcium stone: These are either calcium oxalate stones or calcium phosphate stones. They are the most common type of kidney stone.
- Struvite stone: These stones form because of a urinary tract infection.
- Uric acid stone: This type of stone forms when your urine is too acidic.
- Cystine stones: These form in people with certain hereditary disorders that cause them to excrete too much cysteine, an amino acid, in their kidneys.
Kidney stones typically take years to form. Symptoms don't start until the stones start to move through your urinary tract, which can be incredibly painful.
Medical conditions including diabetes, high blood pressure, or obesity can increase your risk for kidney stones. It is particularly important for people with or at risk for kidney disease to prevent kidney stones, because stones can cause further kidney damage by causing blockages and infections. In fact, the foods you eat and fluids you drink can influence the development of kidney stones.
Here are four of the best ways to prevent kidney stones:
1. Drink more water
Johann Ingimarsson, MD, a urologist at Maine Medical Center, says drinking more water is the first step you should take to prevent kidney stones. This helps dilute your urine, flushing out the kidneys and urinary tract, so that stones don't build up. This will help prevent all four types of stones.
Doctors recommend drinking about three quarts of water a day, although if you are active and sweat a lot, you may want to drink even more than that. For more information, read about how much water you're supposed to drink a day.
Adding lemon to your water, or another type of citrus fruit, may also aid in kidney stone prevention. Lemons are high in citric acid, which helps prevent kidney stones from growing by coating them so that more material doesn't stick to them. If you have uric acid stones, you want to avoid making your urine more acidic, so you may want to try adding orange to your water instead.
For example, a small 2007 study published in the Journal of Urology compared 11 patients on "lemonade therapy" for calcium oxalate stones to a control group. Lemonade therapy consisted of drinking two liters of water with four ounces of lemon juice a day. The study found that the rate of stone formation in the lemonade therapy group dropped from 1.00 to .13 per person per year.
2. Get more calcium
Doctors used to recommend limiting calcium intake to prevent calcium kidney stones, but that hasn't been proven to be helpful advice, says Ingimarsson. Instead, it's now recommended to make sure you get about 800 to 1,200 milligrams of calcium per day.
The reason for this actually has to do with oxalate, a compound found in food and a key component of the most common type of kidney stones. According to a 2014 review published in the journal Translation Andrology and Urology, when calcium and oxalate are eaten in the same meal, they bind together in your stomach and intestines. This helps prevent stone formation. When calcium isn't present, oxalate is absorbed on its own and is excreted in the kidneys, where it can form stones.
It's best to get calcium through your diet, rather than supplements. Foods that are rich in calcium include:
- Milk (250 mg/cup)
- Cheese (200 mg/slice Swiss cheese)
- Kale (117 mg/cup of chopped kale)
- Sardines (351 mg/can of sardines)
3. Cut back on sodium
While you shouldn't limit your calcium intake, you should cut back on sodium. As your blood moves through your kidneys, sodium and calcium compete for reabsorption in the renal tubes. What isn't reabsorbed ends up in your urine. When sodium levels are high, not as much calcium will be reabsorbed, meaning more stays in your urine. If there is more calcium in your urine, it is more likely to form into calcium-based stones.
A 2010 randomized, control study published in the American Journal of Clinical Nutrition followed 200 adult kidney stone patients for three months. All patients were put on a water treatment, consisting of two or three liters of water a day, depending on the season. Half the patients were also put on a low sodium diet. After three months, patients on the low sodium diet had lower urinary sodium and lower urinary calcium compared to the control group. Lower urinary calcium is key to preventing calcium stones.
In addition to regular old table salt, many foods are high in sodium, including:
- Processed foods like chips, crackers, or cereal (one cup of corn flakes has 204 mg of sodium)
- Condiments like ketchup (one tablespoon of ketchup has 160 mg of sodium)
- Deli meats like turkey (one slice of deli turkey contains 250 mg of sodium)
- Canned foods like soups or vegetables (a serving of chicken noodle soup has 849 mg of sodium while a half a cup of canned corn has 320 mg)
4. Be careful with oxalate-rich foods
If you have calcium oxalate kidney stones, you may want to cut back on foods rich in oxalate. Too much oxalate in your urine makes it more likely that the oxalate will bind with calcium in the urine, and that can lead to kidney stones.
"But not everybody that has those stones has high oxalate in urine," says Ingimarsson. For these people, cutting out oxalate rich foods won't do any good, and can lead to poor nutrition.
Rather than cut out oxalate-rich foods, it's a good idea to eat them in the same meal as calcium. That way, the calcium and oxalate bind in your stomach and intestines, and not in your kidneys. When this happens, the calcium oxalate leaves your body in your stool, so it can't form stones.
Oxalate-rich foods include:
- Nuts and nut butters, especially almonds
- Spinach or broccoli
- Soy products
- Coffee or black tea
- Dark sodas like Coke, Pepsi, or Dr. Pepper
When to see a doctor
Even though it is incredibly painful to pass a kidney stone, most of the time medical intervention isn't necessary. If the pain is too much, you can ask your doctor for pain medication. Your doctor may also prescribe medication like tamsulosin or nifedipine to relax the ureter so you can more easily pass the stone.
If you aren't able to pass urine, there is blood in your urine, or you have nausea, vomiting, fever, or chills, you should contact your doctor. In these cases, your doctor may use one of these methods to break up and remove the stone:
- Ureteroscopy. A small scope with a tiny camera is put up the urethra and into the ureter. This allows your doctor to find the stone and remove it, or even crack it with a laser so it can be removed in smaller pieces. Ingimarsson says this approach has the best success rate because you actually see the stone, but there is more of a recovery period and it can be painful.
- Shockwave lithotripsy. This approach is less invasive, but also less accurate because doctors can't see exactly where the stone is. The patient gets in a surgical bathtub and high-energy shock waves are sent through water to the stone's approximate location. The shock waves break the stone apart so it can be more easily passed.
- Percutaneous nephrolithotomy. This is generally reserved for the largest stones. Doctors make an incision in your back and then insert a tube directly into your kidney. An ultrasound probe is used to disintegrate stones and then they are suctioned out. A stent, or internal tube, is placed from the kidney to the bladder and has to be removed a week later.
Takeaways
Staying hydrated and improving your diet can help you prevent or treat kidney stones. However, even with these dietary changes, not everyone will be able to completely prevent kidney stones.
"It is important to remember that two people can eat the exact same diet and one person, due to genetic disadvantage and family history, will form stones and the other doesn't," says Ingimarsson.