From the Guidelines
To prevent calcium oxalate stones, patients should focus on increasing fluid intake to at least 2.5 liters daily, limiting sodium intake to less than 2,300 mg daily, and consuming 1,000-1,200 mg of dietary calcium per day, while also limiting foods high in oxalate such as spinach, rhubarb, beets, nuts, chocolate, tea, and wheat bran. This approach is supported by the American Urological Association guideline 1, which recommends counseling patients with calcium oxalate stones to limit intake of oxalate-rich foods and maintain normal calcium consumption. Additionally, a study published in the Journal of Urology 1 found that increasing fluid intake to achieve a urine volume of at least 2.5 liters daily is a critical component of stone prevention.
Some key points to consider in the diet to prevent calcium oxalate stones include:
- Increasing fluid intake to dilute urine and reduce stone formation
- Limiting sodium intake to reduce calcium excretion in urine
- Consuming calcium-rich foods with meals to help bind oxalate in the digestive tract
- Moderating animal protein consumption to 6-8 ounces daily
- Limiting vitamin C supplements to no more than 1,000 mg daily
- Including citrus fruits like lemons and oranges in the diet to help prevent stone formation
- Avoiding sugar-sweetened beverages and excessive alcohol, which can increase stone risk.
It's also important to note that patients with enteric hyperoxaluria and high levels of urinary oxalate may benefit from more restrictive oxalate diets and higher calcium intakes, which may include supplements, specifically timed with meals 1. However, the evidence from the American College of Physicians guideline 1 suggests that a multicomponent diet including normal or high calcium intake, low sodium intake, and low animal protein intake may be effective in preventing recurrent stones.
Overall, the goal of the diet is to reduce urinary concentrations of stone-forming compounds, bind oxalate in the digestive tract before absorption, and maintain proper urine pH levels to prevent crystal formation, as supported by the study published in the Annals of Internal Medicine 1 and the guidelines for management of patients with a short bowel 1.
From the FDA Drug Label
Throughout treatment, patients were instructed to stay on a sodium restricted diet (100 mEq/day) and to reduce oxalate intake (limited intake of nuts, dark roughage, chocolate and tea). A moderate calcium restriction (400-800 mg/day) was imposed on patients with hypercalciuria
- Dietary restrictions to prevent calcium oxalate stones include:
- Sodium restriction: 100 mEq/day
- Oxalate reduction: limited intake of nuts, dark roughage, chocolate, and tea
- Moderate calcium restriction: 400-800 mg/day for patients with hypercalciuria 2
From the Research
Dietary Recommendations to Prevent Calcium Oxalate Stones
- A low calcium oxalate diet is recommended to prevent the formation of calcium oxalate stones 3, 4
- Dietary restriction of calcium and oxalate, combined with thiazide and potassium citrate, can satisfactorily control hypercalciuria, prevent the secondary increase in urinary oxalate, reduce urinary saturation of calcium oxalate, and virtually eliminate recurrent stone formation 3
- Maintaining dietary Ca intake at 600 to 800 mg/day is recommended to reduce urinary supersaturation of Ca oxalate 4
- Reducing urine oxalate excretion can be achieved by dietary oxalate restriction if urine oxalate excretion is elevated 4
Medical Treatment to Prevent Calcium Oxalate Stones
- Thiazide diuretics can reduce urinary calcium and both calcium oxalate and calcium phosphate supersaturations in calcium oxalate stone formers 5
- Potassium citrate can increase urine citrate levels and reduce calcium oxalate supersaturation in calcium oxalate stone formers 5, 6
- Hydrochlorothiazide and potassium citrate can reduce urinary calcium excretion in patients with calcium oxalate stones and hypercalciuria 6
- Allopurinol can be used to treat calcium oxalate and calcium phosphate stones 7