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If you've ever had a run-in with kidney stones, then you've also had a run-in with a relative/neighbor/obnoxious over-sharer who has the home remedy that fixed them right up.
And while unsolicited after-dinner medical advice may sometimes sound reasonable, there's a lot you need to know about your own kidney stones before you start adjusting your diet based on Aunt Alice's latest stone story.
"You don't want calcium because that's what stones are made of, so ditch the milk."
"Oxalates are bad, so stop eating foods like chocolate, beer, soy, nuts, spinach and coffee."
"And if you feel a stone coming on, start drinking lots of cranberry juice to get rid of it."
You've probably gathered lots of advice and home remedies in your battle against kidney stones (and you probably even asked for some of it). But many of grandma's homemade fixes may actually do more harm than good when it comes to the specific composition of your kidney stones and the reasons why you are forming them.
What are kidney stones? They're crystal-like formations of the excess minerals in your urine. This simple answer leads to simplified — and problematic — responses. The logic: Identify what you're consuming, and reduce whatever the stone is made of.
Four main kinds of kidney stones
There are four main kinds of kidney stones:
Calcium oxalate stones, by far the most common type of kidney stone
Calcium phosphate stones, also very common
Uric acid stones, often associated with diabetes
Struvite stones, often caused by an active infection
The two most common kidney stones include ‘calcium' in their names, so does that mean you should cut out milk and other calcium-rich foods?
Kidney stone myths
MYTH: Kick calcium to the curb
"This is a big myth-buster here," said Kristina Penniston, PhD, registered dietician and researcher in the University of Wisconsin-Madison Department of Urology. "Sometimes we actually need to increase a person's calcium intake. People that form calcium stones will say, ‘What? I've been told to avoid dairy all my life!' To that I say, ‘Yeah, and you've continued to form stones, right?!' "
Many people fear calcium because they hear stones are made of calcium, but the truth of the matter is if your calcium intake is too low, you're at risk for over-absorbing oxalate, a common compound we eat in many foods. Over-absorbing oxalate can lead to extra oxalate in your urine and that can lead to calcium oxalate stones
MYTH: Axe the oxalate!
In some people who form calcium oxalate stones, if there's no other reason (there usually are other reasons!) for that stone formation, then it might be time to try to reduce oxalate intake. After making sure calcium intake is appropriate, then a lower intake of a couple of the most oxalate-rich foods might be recommended. But here's the caveat, said Penniston:
"The foods that are highest in oxalate are also high in fiber, magnesium, potassium, and phytate. These are actually stone inhibitors. Moreover, studies show that when you reduce oxalate, you reduce your fiber intake. That can lead to constipation and other bowel issues. In general, we're trying to help people eat a healthy, balanced diet."
MYTH: Surrendering the salt shaker is a sure thing
Sometimes patients are asked to reduce their salt intake, but if their salt intake is already low, then no amount of salt reduction will prevent stones from forming. But how low is it, really?
"If salt intake is high and if you're forming calcium stones in particular, then we may recommend reducing salt intake," said Penniston. "That's a big problem because people have so many contributors to salt in their diet and they don't even realize it. The salt shaker accounts for about 10 percent of a person's salt intake, so it's really a matter of educating patients."
MYTH: The internet knows all
All four major categories of stone have subcategories within them, so looking at nutritional contributors of stones gets very individualized. There's never going to be a one-size-fits-all stone prevention diet.
"Every time I finish a talk or meet with a patient, that's the main message: It's not about going to the internet and picking out a diet," said Penniston. "Everyone has slightly different stone risk profiles and health needs, and people have different dietary habits on top of that. We can make stone prevention work; it's just a matter of giving it individualized attention."
Ways to prevent kidney stones
All that said, there are some always-good-for-you options that can also help prevent stones.
Here's a short list of recommendations to consider.
Fluids of all types are safe, because they increase urine output and that's a big goal. Dilute urine is your best friend in preventing stones, so drink up.
There are benefits to balance, so eat more fruits and vegetables. "I can't think of a reason why they wouldn't be safe for anybody," said Penniston. "A variety of fruits and vegetables can provide stone prevention benefits for most people. There are some foods like fruits and vegetables that, if we eat more of them, can reduce some of the major risk factors of most types of stones."
Bacteria can be a good thing. The gut microbiome is the hottest new topic when it comes to nutrition. And it turns out that the bacteria that live in our GI tract probably do have a lot more to do with our overall health than we think. "Some of the therapy that we do is aimed at optimizing the gut microbiome, and to do that you have to eat foods that will sustain a healthy colonization of bacteria, like fiber and fruits and vegetables," said Penniston. "Cultured foods like yogurt, and kefir or fermented foods aid the microbiome directly by introducing more bacteria into the digestive tract."
Ultimately, if you are experiencing stones, see your urologist. They can not only help you in the short-term, but they can provide you with information about your stones. Additionally, a registered dietitian can set you up with an individualized diet plan.
"Patients come in and they've been told various things by doctors or nurses or neighbors, and a lot of what we do is redirecting what people have heard "We want to get people to eat what they want to eat while still preventing stones," said Penniston. "Everybody is different with different underlying health conditions like diabetes, high blood pressure, heart disease and so on, and many conditions have their own diet recommendations. We try to integrate a stone prevention diet into existing diet recommendations, so it's about finding what you can eat and making that work for you."