Kidney stones are hard deposits of minerals and salts that form inside the kidneys. They develop when there is a decrease in urine volume and/or an excess of stone-forming substances in the urine. Small kidney stones may go undetected and pass out painlessly in the urine. However, larger stones can block the ureter and cause excruciating pain in the back, abdomen or groin.
Diet plays an important role in both preventing and treating kidney stones. While some foods may increase the risk of developing stones, others may help prevent stone formation or even break down existing stones. Bananas are often considered one of the best foods for people with kidney stones.
How do bananas help with kidney stones?
There are a few key ways bananas may help when it comes to kidney stones:
- Increase urine volume – Bananas are rich in potassium, an electrolyte that helps stimulate urination. More urine output helps flush out excess minerals and salts before stones can form.
- Lower calcium excretion – Some studies show that the potassium in bananas may reduce the amount of calcium excreted in the urine. Less calcium in the urine means a lower risk of calcium stones.
- Protect against cellular damage – Bananas contain antioxidants like vitamin C and phenolic compounds that prevent free radical damage to kidney cells and reduce inflammation.
- Provide fiber – Fiber from bananas can help bind to stone-causing minerals like calcium and flush them out of the body.
Nutritional profile of bananas
Here is the nutrient content in one medium banana (118 grams):
| Nutrient | Amount |
|---|---|
| Calories | 105 |
| Carbs | 27 grams |
| Fiber | 3 grams |
| Potassium | 450 mg |
| Magnesium | 34 mg |
| Vitamin C | 10 mg |
| Vitamin B6 | 0.5 mg |
Bananas are a good source of carbs, fiber, potassium, magnesium and antioxidants like vitamin C and vitamin B6. All of these nutrients are beneficial for people with kidney stones.
Potassium content
One of the biggest advantages of bananas when it comes to kidney stones is their high potassium content. One medium banana contains about 450 mg of potassium.
Potassium helps reduce calcium excretion through the urine by binding to it in the digestive tract. Studies show that as you increase potassium intake, urinary calcium excretion decreases, lowering the risk of calcium-containing stones.
The combination of potassium and magnesium in bananas may be particularly helpful. Some research suggests magnesium and potassium together have an even greater effect on reducing calcium levels in the urine.
Fluid content
Keeping urine diluted is one of the most important ways to prevent kidney stones. Passing about 2 liters of urine daily decreases urine concentration of stone-forming minerals.
Although bananas are not a high water content fruit, their potassium and natural sugars act as an electrolyte to stimulate urination. This increases urine output to help flush out the kidneys.
Fiber content
Most of the fiber in bananas is pectin, a type of soluble fiber that can bind to minerals like calcium to excrete them in the feces rather than the urine. This can help reduce kidney stone risk.
One medium banana contains about 3 grams of fiber. While this is not an extremely high amount, bananas eaten regularly as part of a high fiber diet can significantly increase fiber intake.
Antioxidant content
Chronic inflammation and oxidative stress in the kidneys is linked to a higher risk of kidney stone formation. Bananas contain antioxidants and anti-inflammatory compounds like:
- Vitamin C
- Vitamin B6
- Manganese
- Carotenoids
- Catechins
- Polyphenols
These nutrients reduce inflammation in the kidneys, protect kidney cells from free radical damage and may help prevent stone development.
Do bananas have any downsides?
For most healthy people, bananas do not have many downsides when eaten in moderation as part of a balanced diet. However, some things to keep in mind are:
- Sugar content – Bananas are a high glycemic index food with approximately 14 grams of natural sugars per banana. This can be detrimental for diabetics and prediabetics.
- Acidic – When metabolized, bananas create acidic byproducts that get excreted in urine. This could theoretically increase the risk of uric acid or cystine kidney stones.
- Constipation – While bananas help some people go to the bathroom more due to their fiber and potassium content, some find bananas make them constipated and uncomfortable.
- Allergies – Bananas along with avocadoes, kiwis and chestnuts are common food allergens. Those with latex allergies may also react to bananas.
Overall bananas are safe for most people with kidney stones. However, moderation is key as too much of any food can be problematic.
Tips for adding bananas to your kidney stone diet
Here are some tips for incorporating bananas into your diet to help reduce kidney stone risk:
- Enjoy a banana for breakfast – A banana mixed into a yogurt parfait, smoothie bowl or overnight oats provides potassium, magnesium and fiber to start your day right.
- Slice onto oatmeal or cereal – Banana slices on top of your morning oatmeal or cereal provide extra fruit without excess sugar.
- Make banana “nice cream” – Blend frozen bananas into a creamy, dairy-free ice cream-like dessert for a cool potassium-rich treat.
- Prepare banana bread or muffins – When bananas get overripe, use them in baking rather than tossing them. The nutrients still remain.
- Blend into smoothies – Add banana with leafy greens, nuts and non-dairy milk for a nutrient-packed smoothie without added sugars.
The bottom line
Bananas provide a variety of beneficial nutrients and compounds that may help prevent kidney stones or even contribute to the breakdown of small stones.
A diet high in fiber, magnesium, potassium and antioxidants paired with adequate hydration is key for kidney stone prevention. Bananas can be part of a kidney-friendly eating pattern as long as portion sizes are kept reasonable.
Additionally, speak with your doctor or dietitian about your specific diet needs. Depending on the type of kidney stones you have, they may recommend limiting high-oxalate or acidic foods.
In moderation, bananas can be a nutritious food choice for people with kidney stones or those wanting to prevent future occurrences.