This is a guest post by Laura Schoenfeld, graduate student in public health nutrition, content manager at ChrisKresser.com, and soon-to-be Registered Dietitian. You can learn more about Laura by checking out her blog or visiting her on Facebook.
Anyone who’s had a kidney stone will tell you that they’re one of the worst medical problems you can ever experience. Kidney stones are a common and painful chronic condition seen in otherwise “healthy” patients, and one of the most common disorders of the urinary tract. About a million people in the United States are treated for kidney stones each year, and the prevalence in adult men is almost 12% and around 6% in adult women. (1)
Stones are most common in caucasian adults between the ages of 20 and 50, and once someone develops a stone, they are far more likely to develop another stone in the future. Like most chronic diseases, the incidence of kidney stones has been increasing over the past 30 years. (2) This is likely due to the variety of dietary and lifestyle changes we’ve made as Americans which aren’t conducive to good health.
What are Kidney Stones?
Stones can be formed from a variety of substances, but the most common stones are made of calcium and oxalate that has crystalized in the urinary tract. Other types of stones include struvite, uric acid and cystine. While stones themselves are painful enough, they can lead to more serious conditions such as obstruction of the urinary tract, permanent damage to the kidneys, and even life-threatening infections. I’ve seen patients in the hospital who have come in with necrotic kidneys due to obstruction from a stone, so this can become a serious condition if not managed properly.
Conventional medical professionals take a multi-pronged approach to treating kidney stones, including surgical removal, using shock waves to break up the stone into smaller, passable pieces, and various medications to prevent future stones from forming. There are a few conventional dietary guidelines for preventing future stone formation, but most of these guidelines are based on the composition of the stone, not the true pathology behind why the stone actually formed. After all, why do some people eat junk food, or foods with high calcium and/or oxalate content, drink barely any fluids, and never experience kidney stones, while I’ve had patients who eat healthy diets, drink plenty of fluids, and still develop stones?
While it’s difficult to know why one person is more prone to kidney stones than another, there are a few important strategies to help reduce your stone risk, whether you’ve had one before or you have a family history of stones. And not surprisingly, these aren’t necessarily the guidelines you’re going to hear from your typical nephrologist. (3) The following are my best tips for preventing kidney stones using simple diet changes.
Balance Your Fat Soluble Vitamins
This would be my top priority for any patient suffering from kidney stones, specifically calcium-oxalate stones. As many of Chris’s readers know, we require more than just vitamin D to properly metabolize calcium in our diets and in our blood, yet unfortunately, most nephrologists and dietitians never consider the role other fat soluble vitamins play in calcium metabolism. But vitamin A and vitamin K2 are two nutrients that are critical for balancing out the effects of vitamin D and making sure the calcium from our diet gets deposited into our bones and not into our arteries. (For more information about vitamin A, D, and K2, you can check out my review of a great book on the topic.)
In someone with kidney stones, vitamin A deficiency, vitamin K2 deficiency, and vitamin D excess are all prime suspects to be considered in terms of both absolute amounts and proportions between the vitamins. Chris Masterjohn, PhD has written volumes about the importance of balancing these three nutrients, and especially balancing vitamin A with vitamin D, as an excess of one will lead to a deficiency of the other. In fact, vitamin D excess is considered to be a risk factor for kidney stones in the conventional medical world, and studies show that people exposed to high levels of sunlight (such as lifeguards) are at higher risk for stones. (4, 5, 6, 7, 8) Interestingly enough, adequate vitamin A intake protects against excess vitamin D, as Masterjohn has made clear in his series on the topic.
Vitamin K2 may play an independent role in kidney stone development. As Masterjohn points out, “patients with kidney stones secrete [vitamin-K2 dependent] protein in its inactive form, which is between four and twenty times less effective than its active form at inhibiting the growth of calcium oxalate crystals, suggesting that vitamin K2 deficiency is a major cause of kidney stones.” While the research is still new, I think there’s no reason not to ensure adequate intake of these nutrients in your diet for health maintenance, and you might find it helps with preventing kidney stone formation.
So how can you get more vitamin A and vitamin K2 in your diet? For vitamin A you can eat plenty of organ meats like liver, egg yolks, and full fat dairy products. For vitamin K2, eat liver, grass fed dairy products like ghee, butter, and full-fat cheeses, or natto (if you’re adventurous). If you need to supplement, keep vitamin A around 5,000-10,000 IU per day and try to get these nutrients from a food-based source, such as the fermented cod liver oil and butter oil blend from Green Pasture. Also, try to cut down on alcohol consumption, as excess metabolism of alcohol can impair your utilization of vitamin A, leading to deficiency. (9)
Add Lemon To Your Water
This is a natural treatment that conventional nephrologists have gotten right. While lemon water is often touted as a cleansing or alkalizing drink, the main reason it is helpful in reducing stone formation is its citric acid content.
Citric acid (not to be confused with vitamin C or ascorbic acid) inhibits stone formation and breaks up small stones that are beginning to form.(10) It works in a few different ways. Citrate binds with calcium in the urine, reducing the amount of calcium available to form calcium oxalate stones. It also prevents tiny calcium oxalate crystals that are already in the kidneys from growing and massing together into larger stones. It also makes the urine less acidic, which inhibits the development of both calcium oxalate and uric acid stones. (11)
You’ll need about a half a cup (4 oz) of lemon juice added to water throughout the day to get the same benefits as taking a potassium citrate pill, which is one of the standard pharmaceutical treatments for kidney stones. You can either take this all in one shot, or spread your intake of the lemon juice throughout the day. Try adding half a cup (or more!) of lemon or lime juice to a 32 ounce bottle of water and sip on it throughout the day. If you prefer, you can also try adding apple cider vinegar, which also contains citric acid and is an alkalizing addition to your beverages. (12)
Get your Magnesium
Sometimes it seems like magnesium might be the cure for everything: muscle cramps, headaches, fatigue, insomnia, anxiety, constipation, back pain, brain fog… it might even solve world hunger. I’m kidding of course, but magnesium is definitely one of those magic cure-all dietary supplements that seems to help with a great variety of maladies without much risk for toxicity. That’s why I, like Chris, believe everyone should take a maintenance dose of a magnesium supplement, since it’s hard to get adequate magnesium even in the healthiest ancestral diet.
However, it may surprise you to learn that there’s some research suggesting that magnesium can lower the risk of stone formation. (13, 14, 15) While scientists are still trying to figure out why magnesium has this stone preventing effect, and to determine which forms of magnesium are the most effective at preventing stones in humans, I think it’s safe to say that if you suffer from kidney stones, you’d be smart to ensure that your magnesium intake is adequate.
There are a few ways to up your magnesium intake. The easiest is to simply take at least 400 mg of magnesium in supplemental form on a daily basis. The best types to take are the chelated forms such as magnesium citrate and magnesium malate, as they’re well absorbed. You can also increase your dietary intake by eating pumpkin seeds, spinach, swiss chard, and nuts like almonds and cashews. Be sure to soak your nuts and seeds before eating them, which will help make the magnesium more available. Some people have reported benefits from taking epsom salt (magnesium sulfate) baths, as magnesium is able to be absorbed through the skin.
Whatever your method, just make sure you’re getting it daily in adequate amounts, since at least 50% of Americans have magnesium deficient diets, consuming less than 400 mg per day. (16) And coffee, a common “paleo” treat, may actually cause magnesium deficiency so be careful not to overdo it in the mornings. (17)
Moderate Your Salt
In Chris’s great series on salt, he explains how excess salt consumption can promote stone formation in those who are susceptible:
“Those who are prone to kidney stones may need to reduce their salt intake, as high sodium excretion also leads to a higher level of calcium excretion in the urine. Evidence on this topic is mixed, but it has been demonstrated that excess sodium intake is associated with increased urinary excretion of sodium and calcium, and subjects who consumed the highest levels of sodium tended to have the greatest urinary calcium excretion. Higher calcium excretion may lead to kidney stone formation, particularly if fluid intake is inadequate.”
So even if you’re eating a diet low in processed foods, you may still be taking in a lot of salt through food items like cured meats (e.g. bacon), canned or preserved foods, fermented condiments like pickles, sauerkraut, and kimchi, or simply by adding a lot of salt to your food. While some salt is good, eating tons of bacon and few plant foods is likely going to push you over your sodium needs without matching that sodium intake with potassium, a crucial electrolyte that can actually eliminate the negative effects of excess sodium. So make sure if you’re eating lots of high salt foods that you’re getting in plenty of good sources of potassium, such as bananas, leafy greens, squash, white potatoes, and avocado.
Eat More Carbohydrates
Another problem that people on a run-of-the-mill Paleo diet might encounter is an inadequate intake of carbohydrate. While carbohydrate is not an essential macronutrient in the most basic biochemical description, a very low carb diet can lead to profound health problems in certain individuals, such as depressed thyroid function, nutrient deficiencies like scurvy, and even insulin resistance. Many people eating a Paleo diet tend to eat lower carb simply because of the nature of the ‘banned’ foods being higher in carbohydrate, such as grains and dairy.
While eating Paleo does not equal low carb, it’s a common situation, especially if someone is new to the diet and doesn’t understand that foods like white potatoes are okay for most people to eat. (In fact, it might be good to alternate sweet potatoes with white potatoes regularly, since sweet potatoes are very high in oxalate which could contribute to stone formation!)
Paul Jaminet, PhD has written a great deal of information about the dangers of carbohydrate restriction, and kidney stones is one of them. While I won’t go into the great detail about why very low carb (VLC) diets can increase the risk for stones (you can read Jaminet’s article for that), the issue is likely due to the fact that VLC diets (<15% of calories from carbohydrate) make the urine more acidic due to the excessive amount of protein metabolism, potentially leading to uric acid stone formation. Generally, this is more of an issue on ketogenic diets, but is a risk for anyone whose diet and exercise routine requires a significantly high level of gluconeogenesis (i.e. forming glucose from amino acids/protein). A high protein diet with adequate carbohydrate intake, contrary to popular belief, will not necessarily increase your risk of stones, unless you already have underlying kidney disease. (18)
In addition, per Jaminet, the degradation of oxidized vitamin C is a likely contributor to the development of stones by increasing oxalate excretion. So if you’re not getting enough vitamin C in your diet and your vitamin C needs are increased on a low carb diet, you may be unintentionally contributing to stone development.
Jaminet recommends a minimum of 20% to 30% of energy intake coming from carbohydrates. (19) For a moderately active woman eating 2,000 calories per day, that’s 100-150 grams of carbohydrate from fruits, starchy vegetables like potatoes and sweet potatoes, white rice, and some dairy if tolerated. For a moderately active male eating 2600 calories, they might need more like 180-200 grams of carbohydrates per day.
As activity level and calorie needs increase, you’ll need to increase carbohydrates appropriately to support glycogen stores and activity levels. If you’re eating a low carbohydrate diet (less than 15% of calories per day) and getting kidney stones, I would reconsider your carbohydrate intake and try bumping it up. If you’re eating low carb and have never dealt with kidney stones, then you might be alright staying low carb – it’s up to you to decide!
On the flip side of eating enough carbohydrates, make sure you’re not getting the majority of your carbohydrates from fructose. As Chris mentioned in his article about gout, research has shown that higher intakes of fructose may mediate many of the abnormalities seen in the metabolic syndrome, including elevated triglycerides, due to increases in uric acid production. (20) High levels of fructose intake not only produces excess uric acid, but it also reduces its excretion in the urine. (21)
While fructose in naturally occurring amounts is relatively benign, fructose is commonly found in our food supply as a sweetener, and is often touted as a natural additive to certain foods. One of the biggest culprits in someone eating a “natural” diet is agave syrup, which is advertised as a low glycemic, naturally occurring sweetener derived from the agave plant. However, its fructose content can range to as high as 90%, compared to high fructose corn syrup which contains about 45-55% fructose!
So while fructose from fruit is generally fine, make sure you’re not using high fructose sweeteners like agave or drinking high quantities of fruit juice. And it should go without saying that soda and other HFCS-sweetened beverages should never touch your lips, regardless of your kidney health!
As you can see, eating a comparatively healthy Paleo or ancestral diet does not guarantee you won’t be immune to kidney stones. While the standard American eating big macs and drinking a liter of cola every day might be at a much higher risk, it’s easy to miss out on some of the key nutrients you need to prevent stones from forming if you’re not eating a varied diet with emphasis on nutrient dense foods. If you do have kidney stones, try following the tips above and see if your stones reduce in size or possibly even disappear!
Now you tell me – have you made dietary changes to successfully prevent kidney stones? Share your recommendations in the comments below!
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