What About Kidney Stones?

I get a lot of questions from people who have had the unpleasant and painful experience of kidney stones. Kidney stones are incredibly common in Canada with approximately 10% of all Canadians experiencing at least one kidney stone in their lifetime. For more information on kidney stones in general check out the KFOC information on this website. Diet plays a huge role to prevent forming more kidney stones if you have had kidney stones before.

So where does the diet for kidney stones fit in? Many of the recommendations fit in with general healthy eating (low salt, moderate protein portions and water, water, water) but some might surprise you.

I decided to ask my colleague and friend Melissa Atcheson to help me answer this question. Melissa is the dietitian who manages all of the nutrition consults for kidney stones in our facility. I asked her to give me the highlights of the diet:

• Drink lots of fluids.  Not drinking enough fluids is the most common cause of kidney stones.  No matter what type of kidney stone, the most important thing to do (if your doctor says it is okay) is drink lots of water and drink often.  Try to drink 10-12 cups (2.5-3.0 litres) of fluid each day, spread out through the day.  At least half should be water; milk, calorie-free beverages and lemonade are other good choices.  Avoid drinking grapefruit juice and dark colas (with phosphoric acid).   You are drinking enough when your urine is clear or light yellow.  If it is dark yellow, you are not drinking enough fluids.
• Eat less salt and salty foods.  Don’t add salt when you cook or eat.  Limit convenience foods, fast foods and processed foods.  Avoid foods high in salt like processed meat, salty snacks, canned vegetables, vegetable juices, canned or dried soups, soy sauce, seasoning salts, sauerkraut, olives, pickles and condiments.  Instead, get back to the basics and cook fresh foods from scratch using garlic, lemon, herbs and spices for flavour.  Read labels and aim for no more than 2300 mg of sodium per day.
• Include adequate calcium each day.  Stones are often made up of calcium, but that doesn’t mean that you should avoid calcium rich foods.  Follow Canada’s Food Guide and have 2-3 servings of dairy foods each day.  If you have to take a calcium supplement, take it with your meals.
• If you had a calcium oxalate stone, limit high oxalate foods like spinach, rhubarb, Swiss chard, leeks, beets, nuts, peanut butter, chocolate, strawberries and tea (no more than 2 cups per day, add milk to decrease oxalate).  Avoid vitamin C supplements.
• If you had a uric acid stone, avoid high protein-low carbohydrate weight loss diets, avoid high purine foods such as organ meats, anchovies, herring, sardines, meat-based broths/gravies, alcohol and glucose-fructose sweetened foods.  Do not eat too much meat, fish, chicken or pork.

If you have had a kidney stone in the past, it may also help to:

• Eat a balanced diet that is not too high in animal protein.  Keep portions of beef, pork, chicken and fish to the size of a deck of cards.  Most people do not need more than 2 such portions per day.
• Drink lemonade made from real lemon juice (1/2 cup lemon juice mixed with 8 cups of water).  This may lower urine citrates and help prevent stones from forming.
• Limit sucrose or sugar.
• Avoid vitamin C supplements and cod liver oil.  Do not take more than the recommended dose of vitamin D.  Only take calcium supplements if you are unable to eat adequate amounts of calcium or if recommended by your doctor.
• Maintain a healthy body weight through healthy food choices and exercise.
• Increase fruit and vegetable intake.

These diet recommendations are designed to prevent recurrence of kidney stones, not to treat stones once present, thus should be followed long term.

Here’s a great low sodium summer pasta salad recipe that can be enjoyed by all.

Lemony Orzo Salad (two 1-cup servings)
1 cup orzo pasta
1 red pepper, diced
1 green onion, diced
2 tbsp tarragon, chopped
2 tbsp parsley, chopped
2 tbsp lemon juice
1 tsp garlic, minced
1 tbsp extra virgin olive oil
1/2 tsp black pepper

Cook orzo in boiling water for 8 to 10 minutes. Drain and cool under running water. Add remaining ingredients and serve alongside your favourite grilled meat or fish.

Recipes created by Chef Leslie Cairns