Preventing kidney stones comes down to a handful of daily habits, mostly related to what you drink and eat. The single most effective step is drinking enough fluid to produce at least 2.5 liters (about 10.5 cups) of urine per day. Beyond hydration, your diet plays a surprisingly large role, and some of the conventional wisdom (like avoiding calcium) is actually backwards.
Drink Enough to Hit the 2.5-Liter Mark
The goal isn’t a specific number of glasses per day. It’s a specific urine output: at least 2.5 liters in 24 hours. For most people, that means drinking roughly 3 liters of fluid daily, since you lose some water through sweat and breathing. Water is the best choice, but other beverages count too.
A simple way to gauge whether you’re drinking enough is urine color. Pale yellow to nearly clear means you’re well-hydrated. Dark yellow means you need more. Spread your intake throughout the day, including a glass before bed, since urine concentrates overnight and that’s when many stones start forming.
Eat More Calcium, Not Less
This trips people up. Calcium oxalate is the most common type of kidney stone, so it seems logical to cut calcium. But the opposite is true. Research published in Mayo Clinic Proceedings found that a daily calcium intake of about 1,200 mg (the same amount recommended for the general population) was associated with the lowest risk of kidney stone formation.
Here’s why: when you eat calcium-rich foods alongside a meal, the calcium binds to oxalate in your gut before it ever reaches your kidneys. That bound complex passes harmlessly through your digestive tract. On a low-calcium diet, oxalate has nothing to bind to, so more of it gets absorbed into your bloodstream and filtered through your kidneys, where it can crystallize into stones. Low-calcium diets can also trigger your body to ramp up vitamin D activation, which paradoxically increases the amount of calcium your kidneys excrete.
The key detail: get your calcium from food, not supplements. Calcium-rich foods eaten with meals are protective. Supplements taken between meals don’t have the same oxalate-binding effect and may actually increase risk. Good sources include yogurt, cheese, calcium-fortified orange juice, cereals, and certain vegetables like broccoli.
Watch Your Oxalate Intake
Oxalate is a natural compound in many plant foods. In small amounts it’s fine, but concentrated doses can overwhelm your kidneys. The National Kidney Foundation flags these as the highest-oxalate foods to limit or avoid:
- Spinach, Swiss chard, beet greens, and rhubarb are among the most concentrated sources
- Nuts and nut butters, especially peanuts, almonds, pecans, and cashews
- Chocolate and cocoa
- Sweet potatoes and beets
- Wheat germ and soy-based products
You don’t need to eliminate these foods entirely. The strategy is to pair high-oxalate foods with calcium-rich ones at the same meal so the oxalate gets bound in the gut. A spinach salad with cheese, for example, is far less risky than a spinach smoothie without any calcium source. If you’ve already had a calcium oxalate stone, though, cutting back on the very-high-oxalate items (spinach, rhubarb, beet greens, nuts) makes a real difference.
Cut Back on Sodium
Sodium is one of the less obvious stone drivers. Every extra 6 grams of salt you eat per day pushes roughly 40 mg more calcium into your urine. That’s calcium your kidneys have to deal with, and it raises your stone risk regardless of how much calcium you eat.
The World Health Organization recommends keeping total salt intake under 5 grams per day (about one teaspoon), which is well below what most people actually consume. The biggest sources aren’t the salt shaker. They’re processed foods, restaurant meals, canned soups, deli meats, and salty snacks. Reading nutrition labels and cooking more meals at home are the most practical ways to bring your sodium down.
Moderate Animal Protein
High-protein diets, particularly those heavy in meat, fish, and eggs, create an acid load in your body. Your kidneys respond by lowering urine pH, making it more acidic. Acidic urine is a favorable environment for both uric acid stones and calcium oxalate stones. Animal protein also increases the amount of uric acid and calcium your kidneys excrete.
This doesn’t mean you need to go vegetarian. It means keeping portions reasonable. If you’re eating large steaks, multiple eggs, and protein shakes every day, scaling back could meaningfully reduce your risk. The NIDDK specifically recommends limiting beef, chicken, pork (especially organ meats), eggs, fish, and shellfish for people who’ve already formed stones.
Add Citrus to Your Routine
Citrate is a natural stone inhibitor. It binds to calcium in urine and prevents crystals from growing into full-blown stones. Many stone formers have low citrate levels, and one of the simplest ways to boost them is with real citrus. Harvard Health reports that drinking half a cup of lemon juice concentrate diluted in water each day, or the juice of two lemons, can increase urine citrate enough to likely reduce stone risk.
Lemonade made with real lemons (not powdered mix) works. So does adding lemon or lime to your water throughout the day. It’s a low-effort habit that serves double duty: you get the citrate benefit while also increasing your fluid intake.
Watch Your Weight
Metabolic syndrome, the cluster of conditions that includes excess belly fat, high blood pressure, high blood sugar, and abnormal cholesterol, is strongly linked to kidney stones. A National Kidney Foundation analysis found that people with all five traits of metabolic syndrome were three times more likely to have stone disease compared to people with none. Even having three or four traits roughly doubled the risk.
Losing weight is especially important for people who form uric acid stones, since insulin resistance (a hallmark of metabolic syndrome) makes urine more acidic. Gradual, sustainable weight loss through diet and exercise addresses multiple stone risk factors simultaneously.
Supplements That Can Backfire
Vitamin C is the main supplement to watch. Your body converts excess vitamin C into oxalate, and high-dose supplements can deliver 10 times or more of the 90 mg men need daily (75 mg for women). Harvard Health specifically warns that high-dose vitamin C supplements should be avoided, particularly for anyone with a history of calcium oxalate stones. Getting vitamin C from food (citrus fruits, bell peppers, strawberries) doesn’t carry the same risk because the doses are much lower.
Other supplements flagged by the American Urological Association as potentially stone-promoting include high-dose vitamin D and calcium supplements taken outside of meals. If you take any of these regularly, it’s worth discussing with your doctor whether the dose is appropriate given your stone risk.
Tailoring Prevention to Your Stone Type
Not all kidney stones are the same, and the ideal prevention strategy depends partly on what type you form. If you’ve passed a stone, try to have it analyzed. If you’ve had multiple stones, a 24-hour urine collection can reveal exactly which risk factors (high calcium, high oxalate, low citrate, high uric acid, low urine volume) are driving your stone formation, allowing you to target the right changes instead of guessing.
For calcium oxalate stones, the most common type, the full playbook above applies: hydrate, eat enough dietary calcium, limit oxalate and sodium, moderate protein, and add citrus. For uric acid stones, the priorities shift toward reducing animal protein, losing weight if needed, and making urine less acidic (citrus helps here too). Some people form stones from both pathways, in which case a broad approach covering all the dietary changes is best.