It’s estimated that one in ten people will develop a kidney stone during their lifetime. Kidney stones can affect people of all ages, but they’re most likely to occur between the ages of 40 and 60. And unfortunately, once you experience one kidney stone, you’re likely to develop more.
The good news: healthy diet and lifestyle habits can help manage your kidney stone risk. Consider this “Kidney Stones 101.” Learn all about kidney stones and how you can keep them at bay.
The Urinary System
Kidney stones are created and travel within your urinary system, so here’s a quick breakdown of the components of your urinary system and their functions:
Kidneys: The kidneys are responsible for filtering your blood to remove waste and extra water.
Ureters: The ureters carry urine from the kidneys to the bladder.
Bladder: The bladder stores urine, and healthy bladders can hold about two cups of urine.
Urethra: The urethra carries urine from your bladder to outside your body.
Your kidneys take their job seriously, working around the clock to filter about 150 quarts of blood, which produces up to two quarts of urine each day.
Urine naturally contains substances like calcium, oxalate, and phosphorus. But sometimes, these minerals and compounds become too concentrated within the urine – that’s where the trouble starts. These substances start to crystallize and accumulate together, forming a kidney stone.
Kidney stones range in size. When they’re small, they may travel through your urinary system and pass uneventfully. However, larger stones make their presence known, and can cause some major discomfort as they make their way through your urinary system.
Types of Kidney Stones
The type of kidney stone your body makes determines your course of treatment, as well as how to prevent future stones. There are four main types of kidney stones, classified by the compounds they’re made of:
- Calcium oxalate
- Uric acid
- Struvite
- Cystine
Calcium oxalate stones are the most common type of kidney stone, and they typically form when you have too much oxalate in the urine and not enough fluid. Those with certain conditions may also be more prone to developing calcium oxalate stones.
Kidney Stone Diagnosis & Analysis
Healthcare providers have several tools to help them diagnose kidney stones.
They’ll probably start with your medical history – certain medical conditions or a family history of kidney stones may raise your risk. Lab tests, like a urinalysis (urine test) or blood test, measure levels of minerals that form kidney stones and give your provider a clearer picture of your kidney stone risk. Your doctor may also use imaging tests like an abdominal x-ray or computed tomography (CT) scan to reveal any existing kidney stones.
Once you’ve passed your kidney stone, your doctor can analyze your stone to figure out what type it is. You can typically pass smaller stones on your own, but be sure to use a kidney stone filter to collect your stone. Larger stones may require a minor procedure to remove them.
Kidney Stone Prevention
Nutrition plays a big role in keeping kidney stones at bay. Keep in mind that the specific type of kidney stones your body makes will determine how you can best prevent future kidney stones. These recommendations are for those at risk for the most common type of kidney stones: calcium oxalate stones.
- Eat a moderate amount of protein.
Your body needs protein to build and maintain muscle and tissues, support your immune system, and keep you full after a meal. While protein is an important nutrient in your diet, too much may encourage kidney stone formation. Focus on filling one-fourth of your plate with protein at each meal, and talk with your healthcare provider or a dietitian if you have questions about your individual protein needs.
- Limit foods rich in oxalates.
Your urologist may recommend that you follow a low oxalate diet. The amount of oxalate in the diet affects the amount of oxalate in the urine, and too much oxalate can promote kidney stone formation.
Foods highest in oxalate are:
- Chocolate or cocoa
- Spinach
- Rhubarb
- Beets
- Wheat germ
- Black teas (not green or herbal)
- Tree nuts (almonds, cashew, and hazelnuts are highest in oxalate)
- Legumes (beans, peanuts, and soybeans)
- Eat calcium-rich foods.
“Calcium” is part of calcium oxalate stones – so you should limit it too, right?
Actually, dietary calcium binds to oxalate in the stomach and intestines, which reduces oxalate levels in urine. That’s good news for stone formers. Aim to include 1,000-1,200 mg of calcium in your diet each day. Calcium-rich foods include dairy and soy products, beans, lentils, leafy greens, and calcium-fortified foods, like orange juice, reducing oxalate levels in the urine.
It’s best to get your calcium from food. However, if your healthcare provider has advised you to take calcium supplements, choose a supplement that contains calcium citrate since citrate helps inhibit stone formation.
- Avoid high-dose vitamin C supplements.
High-dose vitamin C supplements may increase your risk of kidney stones since this can increase urinary oxalate levels. Avoid taking vitamin C supplements in large amounts (500 mg or more).
- Choose a low-sodium diet.
A low-sodium diet helps support healthy urinary calcium levels, so aim to keep your sodium intake below 2,300 mg. You can reduce the amount of sodium you get each day by cooking at home more often, choosing less processed and fast foods, reading nutrition facts labels, and switching to pepper, herbs, and spices instead of adding salt to foods.
- Drink plenty of fluids.
Hydration is key in your stone prevention routine. The National Kidney Foundation recommends drinking 2-3 quarts of fluid per day. While water is a great option, consider homemade lemonade, too. Research suggests that lemon juice helps increase urinary citrate levels, reducing your risk for stone formation.
- Increase your magnesium, potassium, and vitamin B6 intake.
Healthy levels of magnesium and potassium citrate help reduce crystallization, and vitamin B6 helps support healthy oxalate levels.* These three nutrients together help support healthy urine chemistry and are a great addition to your prevention toolbox.*
Rich sources of magnesium include legumes, nuts, seeds, and whole grains. Potassium is found in various foods, particularly fruits and vegetables, and you’ll find vitamin B6 in foods like poultry, fish, potatoes, and fruit.
Your kidneys and urinary system work hard to keep you healthy. Focus on these seven tips to help you prevent kidney stones and keep your urinary system running smoothly.