Does cranberry dissolve kidney stones?

Kidney stones can be an extremely painful condition that affects many people. These hard deposits form inside the kidneys and can cause symptoms like severe pain in the back, side, or groin, nausea, vomiting, and blood in the urine. Passing a kidney stone can be an agonizing experience. This has led some people to explore natural remedies like cranberry to try and dissolve kidney stones and provide relief from this condition.

What are Kidney Stones?

Kidney stones form when minerals and salt in the urine crystallize and stick together. The most common types of kidney stones are made up of calcium oxalate or calcium phosphate. Less common types include uric acid stones, struvite stones, and cystine stones. Kidney stones vary in size – they can be as small as a grain of sand or grow to be several inches across. Some factors that can increase your risk of developing kidney stones include:

• Dehydration
• Diets high in sodium, oxalate, and animal protein
• Obesity
• Gastric bypass surgery
• Chronic diseases like diabetes and high blood pressure
• Family history

Small kidney stones may be able to pass through the urinary tract on their own, but larger stones often get stuck and block the flow of urine. This can lead to severe pain, infection, and kidney damage if left untreated. Medical procedures like lithotripsy, ureteroscopy, or nephrolithotomy may be required to break up or remove large kidney stones.

What is Cranberry Juice?

Cranberries are small, sour red berries that grow on low, trailing vines. To make cranberry juice, the berries are pressed to release their liquid. Pure cranberry juice is quite tart, so commercial brands often blend it with sugar, water and other fruit juices to lessen the sourness.

Cranberries contain various vitamins, minerals, and antioxidants. Research suggests that cranberries have potential health benefits including:

• Preventing urinary tract infections
• Reducing inflammation
• Lowering blood pressure
• Increasing antioxidant levels
• Improving immune function

This has led some individuals to theorize that cranberry juice could also help dissolve and flush out kidney stones, due to its effects on urine and the urinary tract.

Evidence on Cranberry and Kidney Stones

There is limited scientific evidence when it comes to using cranberry specifically for kidney stone dissolution. However, some research has been done that provides insights into how cranberry may or may not impact kidney stones:

Animal Research

• A 2016 study in rats with kidney stones found that giving cranberry extract for 60 days reduced the amount of calcium oxalate crystal deposits in their kidney tissue compared to no treatment. It also increased antioxidant levels in their kidneys.
• A 2018 rat study showed that treatment with cranberry extract increased urine output, raised urine pH, and reduced kidney calcium levels in rats fed a high oxalate diet designed to induce kidney stones.

Human Studies

• A small 10-person study in 2021 gave participants cranberry capsules or placebo for 2 weeks. Urine testing showed lower oxalate levels and higher citrate levels in the cranberry group, which could potentially lower kidney stone risk.
• A double-blind trial in 2022 tested different dosages of cranberry extract in people with recurrent calcium kidney stones. The extracts increased urine citrate levels at higher doses, but did not decrease calcium, oxalate, or other stone-risk factors.

Overall the current research shows some potential beneficial effects from cranberry like increasing citrate levels, but there is limited evidence demonstrating actual kidney stone dissolution or elimination in humans.

Potential Risks and Considerations

For most people cranberry juice is safe to consume in normal food amounts. However, there are some risks and considerations to be aware of if drinking cranberry juice specifically to target kidney stones:

• High in oxalate – Cranberries contain moderate amounts of oxalate. For people prone to calcium oxalate stones, a high oxalate intake could potentially increase kidney stone risk.
• Drug interactions – Cranberry may interact with blood thinners like warfarin and impact their effectiveness. Stopping warfarin suddenly could lead to serious complications.
• GI symptoms – Drinking large amounts of cranberry juice can trigger nausea, upset stomach, and diarrhea in some individuals.
• No proven benefits – There is currently no solid clinical evidence that cranberry juice dissolves existing kidney stones or effectively prevents stone formation in humans.

It’s also important to note that not all cranberry juice is created equal. Some juices have very low percentages of actual cranberry, and added sugars or fructose can worsen kidney stone risk. Read labels carefully and select unsweetened or low sugar cranberry juice options.

Other Natural Options for Kidney Stones

While cranberry may offer some potential benefits, other natural substances have more scientific support for targeting kidney stones. Options to consider include:

Lemon Juice

Lemon juice contains high levels of citrate, which helps prevent calcium kidney stones by keeping calcium dissolved. Studies show lemon juice can increase urinary citrate and may slow stone growth.

Apple Cider Vinegar

Apple cider vinegar is thought to dissolve kidney stones and help them pass more easily. It may work by softening stone material and increasing urine flow and volume to flush out deposits.

Basil

Animal studies show basil can decrease urinary oxalate levels and reduce the formation of kidney stones. It is thought to work by suppressing the production of stone-forming crystals.

Potassium Citrate

Prescription potassium citrate is FDA approved for reducing kidney stone recurrence. It raises citrate levels in urine, which helps block stone-forming calcium from crystallizing.

Treatment	Potential Benefits
Lemon juice	Increases urinary citrate
Apple cider vinegar	Softens stone material, increases urine flow
Basil	Reduces urinary oxalate
Potassium citrate	Raises urinary citrate, blocks calcium crystallization

Tips for Using Cranberry

There is limited evidence that cranberry can actively dissolve kidney stones. However, it still may provide some protective effects against stone formation and recurrence. If you want to try using cranberry, some tips include:

• Drink pure, unsweetened cranberry juice – Avoid blends with added sugars
• Consume cranberry juice in moderation – Too much can trigger GI side effects
• Don’t suddenly stop blood thinners like warfarin if drinking cranberry
• Increase fluid intake to flush your urinary system
• Combine cranberry with other kidney stone remedies like lemon juice or basil
• Talk to your doctor before using cranberry long-term, especially if you take medications

When to See a Doctor

Natural remedies like cranberry should not take the place of medical treatment for kidney stones. You should see a doctor or urologist if you experience symptoms like:

• Severe pain in your back, side, abdomen, or groin
• Pain that comes in waves and fluctuates in intensity
• Pain accompanied by nausea, vomiting, fever, or chills
• Pink, red, or brown urine from blood caused by stones
• Sudden pain accompanied by difficulty urinating
• Pain that doesn’t improve with pain medication

Seeking prompt medical attention is crucial if you think you have a kidney stone. Leaving it untreated can allow the stone to grow larger and cause complications like infection or kidney damage.

The Bottom Line

Some research indicates cranberry juice may have protective effects against kidney stones by increasing urine citrate and antioxidants. However, evidence is limited and there are no human studies proving cranberry can actively dissolve or eliminate existing kidney stones.

Cranberry juice is generally safe to try in moderation as part of an overall kidney stone prevention diet. However, it should not replace medical treatment if you are experiencing symptoms of kidney stones. Talk to your urologist to find out the best dietary changes and treatment options for your specific situation.