Kidney stones get worse when your urine becomes too concentrated with minerals like calcium, oxalate, or uric acid. Dehydration is the single most common aggravator, but diet, body weight, certain supplements, and even medications can tip the balance toward stone formation or make existing stones grow. Here’s what specifically drives that process.
Not Drinking Enough Water
Low fluid intake is the most straightforward way to aggravate kidney stones. When you don’t drink enough, your kidneys produce less urine, and the urine that does pass through becomes more concentrated. That concentration allows minerals to reach a point called supersaturation, where they begin crystallizing into stones or adding to stones already present. The less urine you produce, the longer those minerals sit in contact with each other, giving crystals more time to form and grow.
The American Urological Association recommends that all stone formers drink enough fluid to produce at least 2.5 liters of urine per day. For most people, that means roughly 3 liters (about 100 ounces) of fluid daily, though the exact amount varies with climate, activity level, and body size. Water is the best choice. Sugary drinks and some other beverages can work against you, as explained below.
Too Much Salt
A high-sodium diet is one of the less obvious but well-documented stone aggravators. Sodium and calcium are handled by the same transport system in your kidneys, so when your body flushes out extra sodium, it pulls calcium along with it. Research shows that for every 2,300 mg of sodium you consume (roughly one teaspoon of table salt), your kidneys excrete an additional 40 to 44 mg of calcium into your urine. That extra calcium has to go somewhere, and in a concentrated urine environment, it binds with oxalate or phosphate to form stones.
This effect is cumulative. If your diet regularly exceeds the recommended 2,300 mg daily sodium limit, you’re chronically pushing more calcium into your urine than necessary. Processed foods, restaurant meals, canned soups, deli meats, and salty snacks are the usual culprits. Cutting back on sodium is one of the most effective dietary changes for reducing calcium stone recurrence.
High-Oxalate Foods
Oxalate is a natural compound found in many plants, and when it reaches your kidneys in high amounts, it binds with calcium to form the most common type of kidney stone: calcium oxalate. Not all high-oxalate foods are created equal. Spinach is by far the most concentrated source, with a half cup of cooked spinach containing roughly 547 mg of oxalate. A cup of raw spinach has about 316 mg. By comparison, an ounce of almonds has around 72 mg, and a half cup of canned beets has about 76 mg.
You don’t need to eliminate all oxalate from your diet. The key is pairing high-oxalate foods with calcium-rich foods at the same meal. Calcium binds to oxalate in your gut before it ever reaches your kidneys, preventing absorption. A salad with spinach and cheese, for example, is far less likely to aggravate stones than spinach eaten alone. Rhubarb, sweet potatoes, and certain teas and chocolates are other notable sources worth moderating if you’re prone to stones.
The Calcium Mistake
Many people with calcium stones assume they should cut back on dietary calcium. This is one of the most counterproductive things you can do. When you eat less calcium, there’s less of it available in your intestines to bind with oxalate from food. That unbound oxalate gets absorbed into your bloodstream, filtered by your kidneys, and ends up in your urine, where it’s free to form stones. Studies confirm this inverse relationship: lower calcium intake leads to higher urinary oxalate and greater stone risk.
The goal is to get adequate calcium from food (not supplements, which can spike calcium levels in urine if taken between meals) and to eat it alongside oxalate-containing foods. Dairy products, fortified plant milks, and canned fish with bones are all good sources.
Too Much Animal Protein
Diets heavy in meat, poultry, fish, and eggs aggravate stones through a different mechanism. Animal protein is rich in sulfur-containing amino acids, and metabolizing them produces acid. Your kidneys respond by making urine more acidic (lower pH), which creates favorable conditions for uric acid stones. Uric acid stones account for about 10% of all kidney stones and form specifically in acidic urine.
High animal protein intake also increases uric acid production in the blood and reduces urinary citrate, a natural compound that normally inhibits stone formation. Research on uric acid stone formers found that those who ate the most protein had significantly lower urine pH and higher markers of protein metabolism compared to non-stone formers. The effect held even after controlling for obesity and kidney function. For every measurable increase in protein breakdown rate, the odds of forming a pure uric acid stone rose by about 6 to 20%, depending on the marker used.
Sugary Drinks and Fructose
Fructose, the sugar found in high-fructose corn syrup, table sugar, and fruit juice concentrates, raises uric acid levels in the blood and increases its excretion in urine. Large studies across multiple populations have found that people in the highest category of fructose intake have a significantly greater risk of developing kidney stones compared to those who consume the least. Sodas, sweetened iced teas, energy drinks, and fruit punches are the primary sources of excess fructose for most people. Whole fruit, while containing some fructose, comes packaged with fiber, water, and other compounds that blunt its effects.
Vitamin C Supplements
Your body converts vitamin C (ascorbic acid) into oxalate as it’s metabolized. At normal dietary levels from food, this isn’t a problem. But supplemental doses of 1,000 mg per day or more can meaningfully increase oxalate excretion in urine, raising the risk of calcium oxalate stones. Case reports document kidney damage from prolonged high-dose supplementation, including patients taking 2 grams daily for extended periods who developed acute kidney injury from oxalate buildup. If you’re stone-prone, the safest approach is getting vitamin C from fruits and vegetables rather than pills, or keeping supplements well below 1,000 mg.
Certain Medications
Some prescription medications directly promote stone formation. Topiramate, commonly prescribed for epilepsy and migraines, is one of the most well-known offenders. It inhibits an enzyme in the kidney tubules, causing a type of metabolic acidosis that leads to alkaline urine, low citrate levels, and calcium phosphate stone formation. Patients on long-term topiramate treatment develop a characteristic urine profile: high pH, low citrate, and elevated bicarbonate, all of which favor crystallization. If you take topiramate and have a history of stones, that connection is worth discussing with your prescriber.
Loop diuretics, some HIV medications, and certain antacids containing calcium can also shift urine chemistry toward stone formation, though the mechanisms differ by drug.
Insulin Resistance and Excess Weight
Metabolic health plays a bigger role in kidney stones than most people realize. Insulin resistance, the hallmark of prediabetes and metabolic syndrome, directly lowers urinary citrate, one of the body’s main defenses against stone formation. Citrate normally binds to calcium in urine, keeping it dissolved. When citrate drops, calcium is free to crystallize.
Research on calcium stone formers found that those with the highest levels of insulin resistance had significantly lower urinary citrate (475 mg per day) compared to those with the lowest insulin resistance (630 mg per day). Patients with clinically low citrate levels also showed markedly greater insulin resistance. This relationship appears to stem from how insulin resistance alters the way kidney tubules handle citrate, sodium, potassium, and acid. Obesity, high blood pressure, and glucose intolerance, all features of metabolic syndrome, have been epidemiologically linked to higher stone rates. Losing weight and improving insulin sensitivity can lower stone risk through this citrate pathway.
Putting It Together
Kidney stones rarely have a single cause. They form when several aggravating factors overlap: not enough water, too much sodium pulling calcium into urine, excess oxalate from food without enough dietary calcium to neutralize it, acidic urine from heavy meat consumption, or metabolic changes from insulin resistance. The practical upshot is that small adjustments across several of these areas tend to be more effective than a dramatic change in just one. Drinking enough to keep your urine pale yellow, moderating salt and animal protein, eating calcium with meals, and watching fructose and supplement intake collectively reduce the conditions that let stones form and grow.