What Should People with Kidney Stones Avoid Eating?

Maintaining a proper diet is essential for individuals with kidney stones, especially since different types of stones require different dietary adjustments. In the case of calcium-based urinary stones, which are the most common, maintaining nutritional balance and consuming fruits rich in citrate can play a significant role in preventing recurrence.

Staying well-hydrated helps prevent stone formation
One of the most effective ways to reduce the risk of kidney stones is to increase fluid intake. It's generally recommended to drink more than 4 liters of fluids daily to ensure a urine output of at least 2.0–2.5 liters per day. This helps dilute the substances in urine that can lead to stone formation.

Moderate calcium intake is beneficial
Contrary to popular belief, a moderate intake of dietary calcium within normal ranges can actually help prevent calcium-based kidney stones. However, excessive calcium intake—especially through supplements—can increase the risk by raising the level of calcium in the urine. Calcium supplements may only be beneficial for individuals with enteric hyperoxaluria, a specific medical condition.

Limit foods high in oxalate
For individuals with calcium oxalate stones, particularly those with hyperoxaluria, it's crucial to limit consumption of oxalate-rich foods. These include spinach (which contains the highest levels of oxalate), kale, almonds, peanuts, beets, parsley, and black tea. Reducing oxalate intake can significantly lower the risk of stone development.

Reduce sodium consumption
High sodium intake can increase urinary calcium excretion, which in turn raises the risk of kidney stones. It is generally advised to keep daily sodium intake below 2 grams. Cutting back on processed and salty foods can help achieve this goal.

Avoid excessive animal protein
Consuming too much animal protein can elevate levels of uric acid and calcium in the urine while decreasing citrate, which helps prevent stones. This combination makes high-protein diets a potential risk factor for kidney stone formation.

Limit vitamin C and purine-rich foods
Excess vitamin C intake can be converted into oxalate in the body, increasing the likelihood of calcium oxalate stone formation. Additionally, individuals with uric acid-related calcium stones should avoid high-purine foods such as organ meats, sardines, and anchovies, as these can increase uric acid levels and contribute to stone development.