The single most effective thing you can do to prevent kidney stones is drink enough fluid to produce at least 2.5 liters of urine per day. That typically means adding about 1.3 liters of water on top of what you normally drink. But hydration is just the starting point. Diet changes involving calcium, sodium, oxalate, and animal protein can cut your risk by as much as half, and most of these adjustments are straightforward once you understand the logic behind them.
How Much Fluid You Actually Need
The goal isn’t a specific number of glasses per day. It’s a specific urine output: 2.5 liters or more. Urine output below 900 milliliters per day puts even healthy people at significantly higher risk, and for anyone who’s had a stone before, the danger zone starts at about 1.6 liters. The easiest way to gauge whether you’re drinking enough is urine color. Pale yellow to nearly clear means you’re on track. Anything darker means you need more fluid.
Water is the best choice, but it doesn’t have to be your only source. What matters is total fluid volume. If you live in a hot climate, exercise heavily, or work outdoors, you’ll need to compensate for sweat losses on top of baseline recommendations. Keeping a water bottle visible throughout the day is a simple habit that makes a measurable difference.
The Calcium Paradox
Most kidney stones are made of calcium oxalate, so it seems logical to cut calcium from your diet. That instinct is wrong, and following it actually raises your risk. When you eat calcium-rich foods, the calcium binds with oxalate in your digestive tract before either substance reaches your kidneys. Less oxalate in your bloodstream means less oxalate in your urine, and fewer stones.
The target is 1,000 to 1,200 milligrams of dietary calcium per day, spread across meals. “Dietary” is the key word here. Calcium from food works because it meets oxalate right in the gut. Calcium supplements, taken between meals especially, skip that interaction and can increase urinary calcium instead. If you need to supplement, take it with a meal so it can do its binding work. Good sources include dairy products, calcium-fortified juices and cereals, and certain vegetables and beans.
Foods High in Oxalate
If you’ve had calcium oxalate stones, it’s worth knowing which foods deliver the most oxalate. The biggest contributors are spinach, rhubarb, wheat bran, nuts and nut products, and peanuts (which are technically legumes but are very high in oxalate). You don’t necessarily need to eliminate these entirely, but eating them in smaller amounts and always pairing them with a calcium source at the same meal helps neutralize their effect.
Cut Back on Sodium
Sodium and calcium are linked in the kidneys. The more sodium you excrete, the more calcium gets pulled into your urine along with it. High urinary calcium is one of the most common metabolic drivers of stone formation. Reducing sodium intake lowers urinary calcium in a direct, dose-dependent way. Most people eat far more sodium than they realize, since the majority comes from processed and restaurant foods rather than the salt shaker. Reading labels and cooking more meals at home are practical first steps.
Limit Animal Protein
Red meat, poultry, fish, eggs, and seafood are all rich in compounds called purines, which your body converts to uric acid. High animal protein intake raises uric acid in the urine, lowers urinary pH (making urine more acidic), and reduces citrate, a natural stone inhibitor. That combination promotes both uric acid stones and calcium oxalate stones.
You don’t need to go vegetarian. The evidence points to moderating portions of nondairy animal protein rather than eliminating it. A practical approach from the National Kidney Foundation: aim for at least five servings of fruits and vegetables per day, two to three servings of low-fat dairy, and treat meat as a side dish rather than the centerpiece of every meal. Plant-based protein sources like soy and legumes have not been shown to increase kidney stone risk, so they’re a safe swap.
The DASH Diet Connection
The DASH diet, originally designed to lower blood pressure, turns out to be one of the most effective eating patterns for kidney stone prevention. It emphasizes fruits, vegetables, whole grains, low-fat dairy, and limited sodium and animal protein, which checks nearly every box for stone prevention simultaneously. In a large study tracking three cohorts, people who followed a DASH-style diet most closely had a 40 to 45 percent lower risk of developing kidney stones compared to those who followed it least. A separate trial found that a diet with normal-to-high calcium, low animal protein, and low sodium reduced calcium oxalate stone recurrence by 51 percent.
Boost Your Citrate Intake
Citrate is your body’s built-in stone inhibitor. It binds with calcium in urine, preventing crystals from clumping together into stones. People with low urinary citrate are at significantly higher risk, and the simplest way to raise it is to eat more fruits and vegetables. Citrus fruits are particularly effective. In one clinical trial, drinking 60 milliliters (about 2 ounces) of fresh lemon juice twice daily provided roughly 6 grams of citric acid per day, enough to meaningfully increase urinary citrate levels. You can squeeze it into water throughout the day.
For people who need more citrate than diet alone provides, a prescription form of potassium citrate is a standard treatment. It’s commonly used for recurrent calcium stones with low urinary citrate and for uric acid stones, where raising urine pH is a primary goal.
Watch Vitamin C Supplements
Your body converts excess vitamin C into oxalate, and high-dose supplements can tip the balance. In men, taking 1,000 milligrams or more of supplemental vitamin C per day was associated with a 19 percent increase in kidney stone risk. The risk appeared to become significant at total vitamin C intakes of 700 to 800 milligrams daily. Women in the same study didn’t show a significant increase, but the mechanism is the same. Vitamin C from food rarely reaches these levels, so the concern is specifically about supplements. If you’re prone to stones, getting your vitamin C from fruits and vegetables rather than pills is the safer route.
Uric Acid Stones Need a Different Focus
About 10 percent of kidney stones are made of uric acid rather than calcium oxalate, and they form in acidic urine rather than because of excess calcium. Prevention centers on making urine less acidic. Eating more fruits and vegetables naturally raises urine pH, while heavy intake of meat, poultry, fish, and alcohol (especially beer) pushes it in the wrong direction. Limiting added sugars, particularly from drinks sweetened with high fructose corn syrup, also helps.
For people with recurrent uric acid stones, a doctor may prescribe potassium citrate or sodium bicarbonate to raise urine pH to a target range. A 24-hour urine test can identify exactly where your pH, uric acid levels, and urine volume stand, which makes it possible to tailor your prevention plan rather than guessing.
When Diet Isn’t Enough
For recurrent stone formers whose stones keep coming despite dietary changes, medications can target specific metabolic problems. People with high urinary calcium may be prescribed a type of diuretic that reduces calcium excretion. Those with high uric acid and normal calcium levels may benefit from a medication that lowers uric acid production. And for the less common cystine stones, specialized medications can break down the amino acid that forms them. All of these decisions are based on a 24-hour urine analysis, which identifies the chemical imbalances driving your particular stones. If you’ve passed more than one stone, getting that test is one of the most useful things you can do.