Kidney stones: Doctors warn about 10 normal foods that could land you in the ER, and the healthy ones that can stop it

Kidney stones are a painful and surprisingly common health problem, affecting millions of people around the world. These small, hard lumps form inside the kidneys and can cause intense pain, trouble passing urine, and in severe cases, long-term kidney damage.

While your genes, medical history, and how much water you drink all play a role, Healthline says diet is one of the most important factors, both in causing and in preventing stones. By understanding what you eat, you can cut your chances of developing them.

What Are Kidney Stones?

Kidney stones (also called renal calculi) are solid crystals that form when substances in your urine, like calcium, oxalate, or uric acid, build up too much. If there isn’t enough fluid to dilute these substances, they can join together and harden.

Sometimes the stones stay in the kidney, but they can also move through the urinary tract. Large stones can block urine flow, which may cause:

• Sudden, sharp pain in the lower back or belly
• Blood in the urine
• Feeling sick or vomiting
• Pain when passing urine

Main Types of Kidney Stones

• Calcium oxalate stones – the most common type, often linked to high oxalate foods.
• Uric acid stones – linked to eating too much red or organ meat.
• Struvite stones – usually after urinary infections.
• Calcium phosphate stones – linked to high urine pH or certain health problems.
• Cystine stones – rare and genetic.

How Kidney Stones Form

Kidney stones form through a process called crystallisation. When you don’t drink enough water, your urine becomes concentrated. If it contains too much calcium, oxalate, or uric acid, and not enough protective substances like citrate, crystals can start to form. Over time, these crystals can join and grow into stones.

Risk factors include:

• Not drinking enough water
• Eating too much salt
• High doses of vitamin C supplements
• Drinking a lot of cola or fizzy drinks
• Too much red meat

10 Foods That Can Trigger Kidney Stones

• Spinach – Very high in oxalates, which can form calcium oxalate stones (Healthline).
• Beets – Another food rich in oxalates, risky in large amounts.
• Nuts and nut butters – Almonds, cashews, and peanuts are healthy but high in oxalates.
• Chocolate – Contains oxalates, especially dark chocolate.
• Black tea – A major source of oxalates if consumed heavily.
• Red meat – High purine content can raise uric acid levels.
• Salt – Excess sodium makes the kidneys release more calcium into urine.
• Cola drinks – Contain phosphoric acid, which may increase stone risk.
• Processed snacks – Often high in salt and preservatives, straining the kidneys.
• Rhubarb – Extremely high in oxalates.

10 Foods That May Help Prevent Kidney Stones

• Water – The best prevention; 2–3 litres daily helps dilute urine (Healthline).
• Citrus fruits – Lemon, lime, and orange are high in citrate, which blocks stone formation.
• Calcium-rich foods – Milk, yoghurt, cheese bind oxalates in the gut.
• Bananas – Low oxalates and rich in potassium for healthy kidneys.
• Barley water – May help flush out small crystals.
• Cucumbers – Hydrating and low in oxalates.
• Whole grains – Oats, brown rice, and barley provide magnesium to block stones.
• Basil leaves – In Ayurveda, believed to lower uric acid.
• Watermelon – Hydrating and supports urine flow.
• Pomegranate – Rich in antioxidants, may protect kidneys.

Extra Tips to Prevent Stones

• Limit vitamin C supplements.
• Get calcium from food, not pills.
• Avoid too much animal protein.
• Stay active to keep kidneys healthy.
• Monitor urine pH if you’ve had stones before.

When to See a Doctor

• Seek medical help if you have:
• Severe back or belly pain
• Bloody or cloudy urine
• Fever or chills
• Nausea or vomiting

A doctor may order scans like an ultrasound or CT, and treatments can range from more fluids and medicine to procedures like shockwave therapy.

Inputs from TOI