Urologist Dr Viswas M R took to Instagram to share that certain foods, such as spinach, may be associated with kidney stones. “Do spinach and tomatoes cause kidney stones? Tomatoes don’t cause stones. Spinach can cause stones. Just 100 grams of spinach contains 1000 mg of oxalates. It increases oxalate excretion in the kidneys and increases the risk of stones. Tomatoes contain very less oxalates. In fact, they have citrate, which reduces stone risk. Have tomatoes, restrict spinach,” said Dr Vishwas.
Still, if you want to consume “high oxalate foods like spinach, chocolates, and dry fruits”, have moderate calcium intake on those days. “Calcium blocks oxalates in the gut and prevents their absorption,” he added.
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To verify, we reached out to Dr Jitendra Sakhrani, a consultant urologist at Hospitals, Central, who said many people stop eating tomatoes after being diagnosed with stones, thinking the seeds are to blame. “However, that isn’t true for most patients,” he said.
Tomatoes are actually low in oxalates and contain citrate, which helps reduce stone formation. Citrate prevents crystals from sticking together in the urinary tract, benefiting those prone to certain types of . So, in moderation, tomatoes are generally safe and can even fit into a kidney-friendly diet, he mentioned.
The bigger dietary issue is eating too many high-oxalate foods, such as spinach, beetroot, nuts, chocolate, tea, and some dried fruits. “Oxalates can bind with calcium in urine and contribute to calcium oxalate stones, the most common type of kidney stones,” said Dr Sakhrani.
Patients should also realise that stones are rarely caused by just one food. “Low water intake, high salt consumption, dehydration, obesity, genetics, and eating too many processed foods usually have a much greater impact. In cities with hot weather and busy lifestyles, many people do not drink enough water throughout the day, which greatly increases the risk of stones,” Dr Sakhrani elucidated.
One practical dietary strategy is to pair high-oxalate foods with calcium-rich foods like curd, milk, or paneer during meals. “This allows calcium to bind with oxalates in the intestine, reducing absorption and lowering the amount that reaches the kidneys. Ironically, completely avoiding calcium can actually increase stone risk instead of lowering it.”
Another mistake people make is over-restricting their diet after a stone episode. “They eliminate tomatoes, seeds, fruits, and other nutritious foods without proper evaluation. Kidney stone prevention should ideally be personalised since different stones have different causes. A and stone analysis can help identify what really needs to be limited,” Dr Sakhrani said.
The focus should be on balance: drink enough water, reduce salt intake, watch portions of high-oxalate foods, and maintain an overall healthy diet rather than blaming tomatoes alone.
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