Kidney Stone Diet: Foods to Avoid and What Helps

Why diet matters for kidney stone prevention

About 80 percent of kidney stones are made of calcium oxalate. The remainder include uric acid stones, calcium phosphate stones, and struvite (infection-related) stones 1Ref 1Pearle MS, Goldfarb DS, Assimos DG, Curhan G, Denu-Ciocca CJ, Matlaga BR, Monga M, Penniston KL, Preminger GM, Turk TMT, White JR (2014).Medical Management of Kidney Stones: AUA Guideline.Fluid intake targets (>2.5 L urine/day), dietary sodium restriction, oxalate and animal protein guidance, and adequate calcium intake recommendations for stone prevention2Ref 2National Institute of Diabetes and Digestive and Kidney Diseases (2023).Definition & Facts for Kidney Stones.Stone type prevalence (calcium oxalate most common ~80%), definition of kidney stones, and patient education context for prevention. The dietary strategy depends on which type you form, so stone analysis and a 24-hour urine collection are worthwhile after a first stone. Without that information, general advice targets the most common type.

What is the most important dietary change for kidney stones?

Fluid intake is the single most impactful change. The goal, recommended by the American Urological Association, is to produce more than 2.5 liters of urine per day 1Ref 1Pearle MS, Goldfarb DS, Assimos DG, Curhan G, Denu-Ciocca CJ, Matlaga BR, Monga M, Penniston KL, Preminger GM, Turk TMT, White JR (2014).Medical Management of Kidney Stones: AUA Guideline.Fluid intake targets (>2.5 L urine/day), dietary sodium restriction, oxalate and animal protein guidance, and adequate calcium intake recommendations for stone prevention. That generally means drinking 2.5 to 3 liters of fluid daily depending on your activity level and climate. Water is best. Coffee and citrus juice are acceptable. Sugar-sweetened beverages and grapefruit juice appear to increase stone risk in some studies and are better limited.

Dilute urine has lower concentrations of the minerals that crystallize into stones. Think of it as keeping the solution too dilute to form crystals.

Which foods are highest in oxalate — and do you need to avoid them all?

Oxalate is found in many plant foods. High-oxalate foods include:

• Spinach (very high)
• Rhubarb
• Beets
• Nuts and nut butters (especially almonds)
• Chocolate and cocoa
• Wheat bran
• Swiss chard

For calcium oxalate stone formers, the AUA guideline recommends limiting intake of these foods 1Ref 1Pearle MS, Goldfarb DS, Assimos DG, Curhan G, Denu-Ciocca CJ, Matlaga BR, Monga M, Penniston KL, Preminger GM, Turk TMT, White JR (2014).Medical Management of Kidney Stones: AUA Guideline.Fluid intake targets (>2.5 L urine/day), dietary sodium restriction, oxalate and animal protein guidance, and adequate calcium intake recommendations for stone prevention. However, complete avoidance is usually not necessary and may not be beneficial. The key insight is that calcium eaten with oxalate-rich meals binds oxalate in the gut, preventing absorption into the bloodstream and reducing urinary oxalate. So drinking a glass of milk or eating yogurt with a high-oxalate meal is actually protective — more so than simply eliminating oxalate foods.

Does sodium affect kidney stones?

Yes. A high-sodium diet raises the amount of calcium that the kidneys excrete into the urine, which increases the risk of calcium stone formation. The AUA guideline recommends keeping sodium intake below 2,300 mg per day for stone formers 1Ref 1Pearle MS, Goldfarb DS, Assimos DG, Curhan G, Denu-Ciocca CJ, Matlaga BR, Monga M, Penniston KL, Preminger GM, Turk TMT, White JR (2014).Medical Management of Kidney Stones: AUA Guideline.Fluid intake targets (>2.5 L urine/day), dietary sodium restriction, oxalate and animal protein guidance, and adequate calcium intake recommendations for stone prevention. Processed foods, canned goods, salty snacks, and restaurant meals tend to be the largest sodium sources.

Reducing sodium is one of the most effective dietary changes for people who form calcium stones.

What about animal protein and kidney stones?

High intake of animal protein — from red meat, poultry, fish, and eggs — has several effects that promote stone formation:

• It raises urinary uric acid, which can seed both uric acid stones and calcium oxalate stones.
• It increases urinary calcium.
• It reduces urinary citrate, which is a natural inhibitor of crystal formation.

The AUA recommends that stone formers limit animal protein to moderate amounts 1Ref 1Pearle MS, Goldfarb DS, Assimos DG, Curhan G, Denu-Ciocca CJ, Matlaga BR, Monga M, Penniston KL, Preminger GM, Turk TMT, White JR (2014).Medical Management of Kidney Stones: AUA Guideline.Fluid intake targets (>2.5 L urine/day), dietary sodium restriction, oxalate and animal protein guidance, and adequate calcium intake recommendations for stone prevention. This does not mean eliminating protein — it means being mindful that very high-protein diets carry additional stone risk.

Should you avoid calcium to prevent calcium stones?

This is a common misunderstanding. Low dietary calcium actually increases stone risk for most people. Calcium in the gut binds to dietary oxalate before it can be absorbed, so eating adequate calcium (around 1,000–1,200 mg per day from food) reduces the oxalate that reaches the kidneys. The AUA guideline specifically cautions against calcium restriction for calcium stone formers 1Ref 1Pearle MS, Goldfarb DS, Assimos DG, Curhan G, Denu-Ciocca CJ, Matlaga BR, Monga M, Penniston KL, Preminger GM, Turk TMT, White JR (2014).Medical Management of Kidney Stones: AUA Guideline.Fluid intake targets (>2.5 L urine/day), dietary sodium restriction, oxalate and animal protein guidance, and adequate calcium intake recommendations for stone prevention.

Calcium supplements taken between meals — without food — do not provide this benefit and may slightly increase risk. Taking supplements with meals is preferable if supplementation is needed.

Uric acid stones: different rules

Uric acid stones form when urine is persistently acidic and uric acid is high. The approach is somewhat different:

• Reduce purines: found in organ meats, anchovies, sardines, shellfish, and red meat
• Limit alcohol, especially beer and spirits
• Increase fluid intake to dilute uric acid
• Alkalinize the urine (with potassium citrate, which a urologist or primary care clinician prescribes)

If you have gout as well as kidney stones, this pattern is especially relevant to discuss with your clinician 3Ref 3Shastri S, Patel J, Sambandam KK, Lederer ED (2023).Kidney Stone Pathophysiology, Evaluation and Management: Core Curriculum 2023.Pathophysiology and dietary drivers for each stone type; uric acid stone diet (purine reduction, urine alkalinization); 24-hour urine testing as the precision tool for personalized prevention.

Getting a personalized plan: why stone type and 24-hour urine testing matter

General dietary advice covers the most common scenarios. A 24-hour urine collection measures exactly what your kidneys are excreting — calcium, oxalate, uric acid, citrate, sodium, and volume — and lets a urologist identify your specific risk factors. This allows targeted recommendations rather than a generic restriction list. Stone formers who have had more than one stone, or whose first stone was large or required intervention, generally benefit most from this evaluation 1Ref 1Pearle MS, Goldfarb DS, Assimos DG, Curhan G, Denu-Ciocca CJ, Matlaga BR, Monga M, Penniston KL, Preminger GM, Turk TMT, White JR (2014).Medical Management of Kidney Stones: AUA Guideline.Fluid intake targets (>2.5 L urine/day), dietary sodium restriction, oxalate and animal protein guidance, and adequate calcium intake recommendations for stone prevention2Ref 2National Institute of Diabetes and Digestive and Kidney Diseases (2023).Definition & Facts for Kidney Stones.Stone type prevalence (calcium oxalate most common ~80%), definition of kidney stones, and patient education context for prevention3Ref 3Shastri S, Patel J, Sambandam KK, Lederer ED (2023).Kidney Stone Pathophysiology, Evaluation and Management: Core Curriculum 2023.Pathophysiology and dietary drivers for each stone type; uric acid stone diet (purine reduction, urine alkalinization); 24-hour urine testing as the precision tool for personalized prevention.