We rely on our kidneys to filter blood and make urine, but every so often they make stones, too.
Kidney stones are associated with pain for a reason — they’re rock-like mineral deposits that form when your pee becomes too concentrated, allowing minerals to crystallize and stick together. They can be as small as a grain of salt or, in extremely rare cases, as large as a ping pong ball. Some cause severe pain while others go unnoticed.
Stones can be caused by low fluid intake, diet, family history and genetics and certain health conditions, medications and supplements. While small ones may pass on their own, others need medication to pass more easily or need to be broken up by medical procedures to avoid an infection or blockage.
There are many myths about how to prevent and manage them, particularly through fluids, diet and avoiding certain foods.
“It is always best to meet with a registered dietitian for a nutrition assessment,” says Heather Kearney, registered dietitian at Calgary Foothills PCN. “We can help identify factors in your diet that are likely playing a role in kidney stone formation.”
The most common type of kidney stone forms from calcium and oxalate — a compound found in many healthy foods and a natural waste product made by the body. But wait — before you throw out all foods that contain calcium and oxalate, keep reading. It’s not that simple!
Eating enough calcium-rich foods — such as milk and other dairy products, canned salmon with bones, kale and collard greens — can actually help lower your risk of kidney stones. Calcium binds to oxalate in the gut, so less oxalate is absorbed into the body.
And while you might be tempted to limit large amounts of some high-oxalate foods, such as spinach, rhubarb, beets, Swiss chard, almonds, cashews and potatoes with the skin on, most people do not need to avoid these foods completely.
“Most of us don’t need to follow a strict diet low in oxalates,” says Kearney. “In fact, a very low-oxalate diet can potentially make things worse. The way stones form is complicated.”
Whether you’ve had kidney stones before or not, you probably don’t need to follow a strict diet. Kearney recommends the following simple tips to prevent stones —find similar ones from Alberta Nutrition Services:
While some people do need to limit foods high in oxalate, it’s best to check with your doctor or a registered dietitian first, says Kearney.
When a kidney stone grows big enough to be a problem, you’ll feel it — many people experience sudden or wave-like intense pain or cramps in their back or ribs. That typically means the stone has blocked the ureter — the tube that carries urine between the kidney and the bladder.
You might also notice changes when you pee: there could be blood or a burning sensation, or you could be peeing more or less than usual. Those kinds of symptoms mean it’s time to see a doctor or care provider, who may refer you to an ultrasound or 24-hour urine test to be sure.
If you keep having kidney stone issues, you might be referred to a PCN registered dietitian for dietary advice. You can also self-refer for an appointment if you need support right away.