Kidney stones are hard deposits made of minerals and salts that form inside your kidneys. They develop when your urine contains more crystal-forming substances – such as calcium, oxalate and uric acid – than the fluid in your urine can dilute. At high concentrations, these substances form crystals that group together to form kidney stones.
Diet is one of the biggest risk factors for kidney stones. While some dietary factors can increase your risk, others may be protective. This article reviews the foods that are most likely to either promote or prevent kidney stone formation.
Foods That Increase Your Risk of Kidney Stones
Several foods can increase your risk of developing kidney stones. Here are some of the top dietary risk factors.
1. High-Oxalate Foods
Oxalate (oxalic acid) is a naturally occurring compound found in a variety of foods. When oxalate combines with calcium in your urine, it forms calcium oxalate, which is the most common type of kidney stone.
High-oxalate foods include:
- Spinach
- Beets
- Swiss chard
- Soybean crackers
- Peanuts
- Wheat bran cereals
- Strawberries
- Chocolate
- Beer
- Black tea
For some people, consuming high amounts of high-oxalate foods can increase the amount of oxalate in the urine by 10–20% (1).
2. Low-Liquid Diet
Not drinking enough fluids is another major risk factor for kidney stones.
People with low fluid intakes produce little urine, which allows stone-forming salts to solidify and stick together. Low urine volume also raises urine concentration of stone-forming salts like calcium, oxalate and uric acid.
It’s generally recommended to drink 2–3 liters (68–102 oz) of total fluids per day, but the ideal amount varies by the climate and your activity level.
3. High-Sodium Diet
Eating a diet high in sodium may increase your risk of developing calcium stones by increasing the amount of calcium in your urine (2).
High-sodium foods include:
- Processed meats like sausages, deli meats and hot dogs
- Canned foods
- Frozen meals
- Fast foods
- Packaged snacks
- Salted nuts
- Cured meats
- Sauces and condiments
- Cheese
Cutting processed foods may help limit the amount of sodium in your diet.
4. High-Sugar Diet
Eating lots of sugar may increase your risk of kidney stones.
One study found that people who consumed more than 200 grams of fructose per day were 30% more likely to develop kidney stones than those consuming the least fructose (below 100 grams per day) (3).
Sugary foods that are high in fructose include:
- Added sugars like table sugar
- High-fructose corn syrup
- Honey
- Sweetened drinks like juices and sodas
- Candy
- Many prepackaged baked goods
5. High-Protein Diets
Eating a diet high in animal proteins like meat, fish and eggs may increase your risk of kidney stones.
Animal proteins contain purines, a class of compounds that can increase uric acid production. This may raise uric acid levels in urine, increasing the risk of uric acid kidney stones.
One large controlled study found that eating more than 2 ounces (60 grams) of animal protein daily nearly doubled the risk of forming uric acid stones, compared to eating less than 2 ounces (60 grams) daily (4).
Foods That Decrease Your Risk
Along with cutting back on foods that increase your risk, eating more of certain foods may help reduce kidney stone formation.
1. Calcium From Food
Getting calcium from foods may lower the risk of kidney stones. In contrast, calcium supplements may increase your risk.
One study found that consuming more than 1,000 mg of supplemental calcium per day was linked to a 17% higher risk of kidney stones, while dietary calcium intake was associated with a 15% lower risk (5).
Calcium-rich foods include:
- Milk
- Yogurt
- Cheese
- Leafy greens like spinach and kale
- Calcium-set tofu
- Beans
2. Citrus Juice
Drinking citrus juices like orange, lemon and grapefruit may lower kidney stone risk. The citric acid in these juices helps prevent stones from forming (6).
One study found that drinking around 2 cups (500 ml) of lemon juice per day raised citrate levels in urine and reduced calcium stone formation by nearly 50% (7).
3. Magnesium From Food
Getting magnesium from foods may help prevent calcium oxalate stones. Magnesium hinders stone formation and decreases oxalate absorption from your diet (8).
High-magnesium foods include:
- Nuts
- Seeds
- Legumes
- Whole grains
- Green leafy vegetables
4. Potassium-Rich Foods
Potassium citrate lowers calcium levels in urine, helping prevent calcium stone formation. Eating potassium-rich fruits and vegetables may provide similar benefits (9).
Foods high in potassium include:
- Bananas
- Potatoes
- Leafy greens
- Beans
- Salmon
- Avocados
5. Plenty of Fluids
One of the most important things you can do when it comes to kidney stones is drink plenty of fluids, especially water. This helps dilute your urine, decreasing stone-causing chemicals.
Aim for 2–3 liters (68–102 oz) of total fluids per day to maximize your dilution potential.
The Bottom Line
Making specific changes to your diet may help reduce your risk of developing kidney stones. However, certain dietary factors could increase the likelihood of forming stones.
Eating a diet that’s high in oxalate, sodium, animal protein and sugar has been linked to a higher risk of stone formation, while getting enough calcium, potassium and magnesium from foods may help prevent kidney stones.
Additionally, make sure you’re drinking plenty of water and other fluids like citrus juice to help dilute your urine and decrease your risk of kidney stones.
Foods to Limit to Prevent Kidney Stones
| Food | Portion |
|---|---|
| Spinach | 1 cup |
| Rhubarb | 1/2 cup |
| Beets | 1/2 cup |
| Swiss chard | 1/2 cup |
| Nuts and nut butters | 1/4 cup |
| Chocolate | 1 ounce |
| Cola | 12 ounces |
| Wheat bran | 3/4 cup cereal or 2 tablespoons bran |
| Fresh berries | 1/2 cup |
| Beans, lentils, soybeans | 1/2 cup |
| Spinach | 1 cup |
| Tea | 8 ounces |
| Okra | 1/2 cup |
| Soy milk | 8 ounces |
Foods that Help Prevent Kidney Stones
| Food | Portion |
|---|---|
| Lemon juice | 1/4 cup or 4 ounces |
| Orange juice | 1/4 cup or 4 ounces |
| Grapefruit juice | 1/4 cup or 4 ounces |
| Watermelon | 1 cup cubed |
| Apples/pears | 1 medium |
| Grapes | 1 cup |
| Bananas | 1 medium |
| Carrots | 1 medium |
| Skim milk | 8 ounces |
| Yogurt | 6 ounces |
| Tofu | 1/2 cup |
| Eggs | 2 |
| Fish | 3-4 ounces |
| Poultry | 3-4 ounces |
| Beans | 1/2 cup |
Tips to Lower Your Risk
Aside from limiting foods that may promote kidney stones, a few other diet and lifestyle tips may help reduce your risk.
Here are some suggestions:
- Drink 8–10 glasses (2–3 liters) of water per day.
- Limit your daily sodium intake to 2,300 mg or less.
- Eat fewer processed foods, which tend to be high in sodium.
- Consume produce high in citrate like citrus fruits, melons and berries.
- Eat plenty of fruits and vegetables rich in magnesium and potassium.
- Reduce your intake of sugary foods, refined carbs and high-fructose corn syrup.
- Limit protein from animal sources to no more than 2 ounces (60 grams) per day.
- Get adequate calcium, phosphorus and vitamin D from foods or supplements.
Conclusion
Kidney stones affect around 9% of people worldwide (10). While some dietary factors may increase your risk, others can help reduce stone formation.
Limiting foods high in oxalates, sodium, animal protein and sugar may help decrease your risk. Conversely, getting enough calcium, citrate, magnesium and potassium from foods could provide protection.
Most importantly, make sure to drink plenty of fluids to dilute your urine and flush kidneys stones out of your urinary system.