Kidney stones are a prevalent health issue, affecting a significant portion of the population. It’s estimated that one in ten people will develop a kidney stone at some point in their lives. These stones are hard deposits made of minerals and other materials inside the kidneys. If you’ve ever had a kidney stone, you’ll likely do just about anything to avoid having another. They can cause extreme pain, often compared to childbirth. The good news is that dietary changes can make a positive difference. This article focuses on brushite stones, exploring their formation, prevention, and management through dietary modifications.
Understanding Brushite Stones
Brushite stones are a less common type of kidney stone, often mixed with calcium oxalate and/or carbonate apatite. These stones are composed of brushite, a calcium phosphate mineral. A study examined the profile of patients and the impact of diet on the risk of brushite stone formation under controlled, standardized conditions. The study revealed that all patients had at least one abnormality on their usual diet, with hypercalciuria (84.6%), increased urine pH (61.5%), and hyperphosphaturia (43.1%) being the most common.
General Dietary Recommendations for Kidney Stone Prevention
While there isn’t a single diet plan that can cure or prevent all kidney stones, certain general recommendations apply to all types. These include:
- Hydration is Key: Drinking enough liquid, mainly water, is the most important thing you can do to prevent kidney stones. Staying hydrated dilutes the urine, so crystals can’t clump together and become stones. People with a history of kidney stones should drink a lot of water - at least 2 liters (8 cups) a day, but ideally 3 liters (12 cups). Unless you have kidney failure, many health care professionals recommend that you drink six to eight, 8-ounce glasses a day. When it’s hot outside, or if you work in a hot environment, you should drink even more water because the more you sweat, the less urine you produce. You can count coffee, tea, and soup as part of your liquids intake, but avoid sugary drinks - especially those containing high-fructose corn syrup.
- Limit Sodium Intake: Your chance of developing kidney stones increases when you eat more sodium. Extra sodium causes you to lose more calcium in your urine. Sodium and calcium share the same transport in the kidney so if you eat high sodium foods it will increase calcium leakage in the urine. Therefore, a high sodium diet can increase your chances for developing another stone. A high-sodium (salt) diet increases your chance of getting phosphate stones. Aim to follow federal guidelines that recommend limiting your sodium intake to 2,300 milligrams daily. You can lower your sodium intake by choosing fresh low sodium foods which can help to lower calcium leakage in the urine and will also help with blood pressure control if you have high blood pressure. Sodium is a part of salt. Sodium is in many canned, packaged, and fast foods. Talk with a health care professional about how much sodium should be in what you eat. Reducing sodium, or salt, also benefits the kidneys by helping to lower blood pressure. Chronic high blood pressure can narrow and weaken the blood vessels in the kidneys, reducing blood flow. Over time, that can make the kidneys stop working properly, leading to kidney disease or kidney failure.
- Moderate Animal Protein Intake: Although you may need to limit how much animal protein you have each day, you still need to make sure you get enough protein. Eating too much animal protein can increase your risk of developing kidney stones. This doesn’t just mean red meat. It also includes chicken, pork, fish, and eggs. If you have calcium phosphate stones, replacing animal proteins with more plant-based proteins, like beans, peas, and lentils, soy foods, nuts, and seeds, can be beneficial. Limit your meat intake to 8 ounces a day. A serving should be no bigger than a pack of playing cards.
- Increase Fruit and Vegetable Intake: A diet rich in fruits and vegetables can lower blood sugar and blood pressure, reduce the risk of heart disease and stroke, and prevent some types of cancer. It also can help prevent the formation of kidney stones by increasing urinary citrate, a naturally occurring acid in the body that prevents calcium bits from sticking together in your urine and forming stones. So, if you need an added incentive to make sure you’re getting your five portions of fruit and vegetables every day, remember that it can help prevent the excruciating pain of another kidney stone. A healthy diet plan that has mostly vegetables and fruits, whole grains, and low-fat dairy products is recommended.
- Maintain a Healthy Weight: Studies have shown that being overweight increases your risk of kidney stones. If overweight, losing weight can vastly improve your health and reduce your risk for stones.
Specific Dietary Considerations for Brushite Stones
Based on the characteristics of brushite stone formers identified in the study, the following dietary considerations may be beneficial:
- Manage Calcium Intake: Even though calcium sounds like it would be the cause of calcium stones, it’s not. In the right amounts, calcium can block other substances in the digestive tract that may lead to stones. Talk with a health care professional about how much calcium you should eat to help prevent getting more calcium phosphate stones and to support strong bones. It may be best to get calcium from plant-based foods such as calcium-fortified juices, cereals, breads, some kinds of vegetables, and some types of beans. Don't reduce the calcium in your diet. Aim for 1,000-1,200 mg calcium per day.
- Monitor Urine pH: Increased urine pH was a common finding in brushite stone formers.
- Control Phosphate Excretion: Hyperphosphaturia (excessive phosphate in the urine) was also prevalent. The relative supersaturation of brushite, apatite, and calcium oxalate decreased significantly under the balanced diet, mainly due to the significant decline in urinary calcium, phosphate, and oxalate excretion.
The Role of Oxalate
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 have high levels of oxalate include peanuts, rhubarb, spinach, beets, Swiss chard, chocolate and sweet potatoes. High levels of oxalate in the urine can contribute to kidney stone formation. Switching to a diet low in oxalates can reduce your risk of calcium oxalate stones. Foods that are highest in oxalates include spinach, rhubarb, baked potatoes, lentils, navy beans, bran, grits and almonds. Pair calcium-rich foods with oxalate-rich foods. Eat and drink calcium foods such as milk, yogurt, and some cheese and oxalate-rich foods together during a meal. The oxalate and calcium from the foods are more likely to bind to one another in the stomach and intestines before entering the kidneys. This will make it less likely that kidney stones will form.
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Other Types of Kidney Stones
Knowing the type of your kidney stone will help determine its cause and give you clues on how to reduce your chance of developing more stones.
- Calcium Oxalate Stones: most common stones. The majority (about 70%) of kidney stones are calcium oxalate stones.
- Uric acid stones: another common stone. Uric acid stones can form in people who lose too much fluid because of chronic diarrhea or malabsorption, eat a high-protein diet or who have gout.
- Struvite stones: Struvite stones can form after a urinary tract infection. They occur more often in females.
Additional Considerations
- Vitamin C Intake: A study published in JAMA Internal Medicine found that men who ingested vitamin C supplements of 1,000 mg a day or more were at increased risk for kidney stones.
- Consult a Professional: A dietitian who specializes in kidney stone prevention can help you plan meals to prevent kidney stones. Kidney stone formation is specific to each person, so it's important to work with your healthcare team to develop a personalized treatment plan.
Medical Interventions
Unfortunately, there are no foods that you can eat to make existing stones disappear. They have to pass on their own or be surgically removed. If the stone is too large to pass, or if blood and urine testing show an associated bladder infection or kidney damage, you may need a procedure to take care of the stone and other concerns.
UT Southwestern kidney specialists perform more than 1,100 procedures each year to remove kidney stones, using two primary methods:
- Ureteroscopy with laser lithotripsy: For small to medium-sized stones, we can insert a small scope with a laser into the ureter to break up the stone into small, passable pieces.
- Percutaneous nephrolithotomy: For large or complex stones, we pass a scope into the kidney through a small incision in the back. The surgeon will fragment the stone with a laser and remove the pieces.
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