Doing all the right things but still have aches and pains? Certain compounds in some vegetables and other plant foods could be the culprit, Celeste McGovern reports
As far back as she can remember, Sally Norton was health-conscious. She adopted a vegetarian lifestyle as she entered college, and eight years later, she turned to a full-on vegan diet, which lasted another eight years. In seventh grade, she decided to pursue the field of nutrition, and in the ’80s she studied at Cornell University, where plant-based nutrition was becoming accepted by some professors and many fellow students.
Norton was all-in. “We were proudly avoiding salt, fat and meat, gorging on bagels, salads and dishes scored by others as ‘veggie glop,’” she says.
But for someone shopping only the fresh food aisles, Norton wasn’t feeling like the model of plant-based health. She had joint and muscle pain, fatigue, and eventually bloat, irritable bowel and a debilitating sleep disorder.
When she was just 20 years old, a doctor told her that the pain in her big toe was the result of gout—an excruciating condition commonly tied to red meat and alcohol consumption in which urate crystals accumulate in the joints. Very strange for a young vegetarian.
After a bout of inexplicable genital pain and burning, she stumbled on the Vulvar Pain Foundation (thevpfoundation.org). The group links connective tissue syndrome including genital (vulvar) pain, interstitial cystitis, fibromyalgia, irritable bowel and sensitive skin to high oxalate consumption. It has helped thousands of women as well as men with scrotal pain to recover using a low-oxalate diet.
Oxalates are organic compounds in various plants that help to ward off pests and manage minerals. When these foods are eaten raw and in too high amounts, they can cause problems in susceptible individuals.
However, without understanding the global effects of oxalate, it took Norton over three years to get serious about sticking to a low-oxalate diet. Finally, just before she turned 50, her health transformation really began. She removed the last vestiges of high-oxalate foods from her diet—a daily kiwi and modest portions of sweet potato several times a week.
Within days, her sleep and joint pain improved dramatically. Before making the change, she says, “I could barely stand barefoot at the kitchen sink.” But afterward she found herself at a nephew’s wedding, running across parking lots and down stairs in heels, standing about for hours and posing for pictures—all pain-free. This scenario would have been unimaginable before.
Norton threw herself into researching oxalates after her own experiment. The information her search revealed led to her book Toxic Superfoods (Rodale Books, 2023).
Norton’s deep dive into oxalates at the university medical library uncovered a forgotten history. Long before green smoothies and almond flour baking, foods rich in oxalates were recognized as a chemical hazard, not as health foods.
In the late 1700s and early 1800s, oxalic acid was widely used in industry under names like “salts of sorrel,” “liquid blue” and “essential salts of lemon.” Textile workers used it for bleaching, engravers used it for etching and households kept it as a cleaning powder. Its usefulness stemmed from its strong ability to bind minerals—the same property that makes it dangerous.
Medical case reports from the early 19th century documented accidental and intentional poisonings, describing symptoms ranging from burning pain to kidney failure. By 1846, physicians were already writing about oxalates’ neurotoxic effects.
They linked the antinutrients (see below) to fatigue, skin disorders, bladder pain, arthritis and personality changes. One early author noted that high oxalate exposure resulted in a constellation of problems “in the nerves, bones and viscera.”
Where did this understanding of oxalates as potentially fatal poisons go? It certainly wasn’t integrated into nutritional science; Norton had only learned of them in terms of kidney stone risk while studying for her nutrition degree and her master’s degree in public health.
In our world of health gurus and public health dictates that offer conflicting advice on everything from coffee and dairy to fat and meat consumption, the only common denominator seems to be “Eat your greens.” And lots of them.
“Blaming produce and nuts for health problems sounds like blasphemy,” says Norton.
But considering how many people are suffering today with chronic maladies that they just can’t figure out, maybe it’s time to question a dogma that says all plants are good for all people at all times. Obesity, diabetes, arthritis, fatigue disorders, neuropathies, thyroid issues, digestive syndromes, urinary problems, mood disorders and autoimmune conditions have all soared in the decades since low-fat, plant-heavy guidelines took center stage.
The potential for harm from oxalate is absent in the messaging from public health and the wellness industry, which both stress minimizing animal proteins in favor of plant-heavy, low-fat eating. They often give tips like these:
For people taking this health advice to heart, oxalates can stack up fast:
That’s not to say oxalates are responsible for all modern illness. But the possibility that they’re contributing quietly hasn’t been part of the public conversation, and maybe it should.
No matter how celebrated their superfood status, high-oxalate plants may be quietly wreaking havoc on some people’s health at the cellular level.
Modern medicine hasn’t entirely forgotten oxalates. They’re recognized almost exclusively within nephrology, the branch of medicine that deals with kidney health.
Here, the relationship is unmistakable: Roughly 80 percent of kidney stones are composed of calcium oxalate. Studies clearly link high urinary oxalate excretion to chronic kidney disease progression and end-stage kidney disease.1
Kidney stones are on the rise, too. Affecting around one in every 11 Americans and about one in 10 people in the UK, they’ve achieved notoriety as a significant public health issue.2
Patients like Australian actor Liam Hemsworth are too often not warned that high-oxalate foods can trigger stones because exceeding 150–200 mg of daily oxalate intake can overburden the kidneys. Hemsworth famously had to undergo surgery to remove kidney stones after consuming a spinach-and-almond smoothie every morning during his four-year stint as a vegan.
Case reports in the medical literature also describe oxalates causing serious kidney damage. One 65-year-old woman who completed a 10-day green-smoothie cleanse using oxalate-rich vegetables and fruit became dialysis-dependent after her kidneys failed due to oxalate damage.3
In another case, the Mayo Clinic reported a man, also attempting to lose weight, whose daily juicing of celery, carrots, parsley, beets with their greens, and spinach led to serious kidney damage. He stopped juicing and started dialysis plus a low-oxalate diet, and about four months later his kidney function began improving.4
Another paper describes three children who presented with pain on urination and cramps in their lower back, while two of them occasionally had blood in their urine. One girl, just 10 years old, had already had surgery to remove kidney stones a year earlier. All three children had been switched onto dairy-free diets and were drinking about four glasses of almond milk each day and consuming almond yogurt and butter.
Almonds are naturally extremely high in oxalates, and almond milk is low in phosphorous compared to dairy milk, so there’s little to buffer the excess oxalates. The researchers speculated that homemade almond milk might cause even more problems than dairy because it has much higher oxalate and lower calcium.5
One 59-year-old woman with no history of urinary stones or use of nonsteroidal anti-inflammatory drugs (NSAIDs) to explain it had an elevated creatinine blood test, indicating kidney damage. Her diet included 6 tablespoons of chia seeds and five handfuls of almonds daily, following the “Virgin diet” to manage irritable bowel symptoms.
The rest of her blood tests were normal. It was only a kidney biopsy that showed glomerulosclerosis (scarring or hardening of the microscopic filtering units in the kidneys) and calcium oxalate deposits. She switched to a low-oxalate diet, and soon her lab markers improved.
“An earlier dietary history could have raised concern for oxalosis prior to renal biopsy,” doctors at the Cleveland Clinic and George Washington University School of Medicine concluded. “Providers should be trained to identify at-risk patients and provide appropriate dietary counseling.”6
How do we know if we have high oxalates? The most common way clinicians look for oxalate problems is by measuring how much oxalate is excreted in the urine, usually with a 24-hour urine collection. Sometimes this standard medical test doesn’t reveal elevated oxalates because it can be taken at the wrong time, says Norton.
Studies have shown a 24-hour collection can miss transient spikes in urinary oxalate that may be crucial for crystal formation and stone growth. So a “normal” result doesn’t always rule out heavy oxalate turnover at other times of the day.
In other words, oxalate excretion isn’t constant. It fluctuates based on what you eat, when you eat it, how well your gut is absorbing nutrients and individual metabolic factors, so one snapshot can miss important surges.
As well, oxalates stored in tissues sometimes get released in bursts—a phenomenon known as “oxalate dumping”—that aren’t captured by the timing of routine testing. When stored oxalates mobilize outside the collection window, the urine test can come back reassuringly normal.
This can happen even when the body is under significant oxalate stress. A normal result makes it easy for doctors to miss the problem unless they take a detailed dietary history and consider symptoms alongside lab results.7
This is a blind spot with consequences, says Norton. People with oxalate overload are often told that nothing is wrong, that their pain or fatigue is “normal” or that their labs are reassuring, while their underlying oxalate pileup compounds. Non-kidney doctors, including general practitioners, endocrinologists, gastroenterologists and rheumatologists, see oxalate-related symptoms in their patients without knowing it.
The historical focus on the kidneys in oxalate-related medical testing and research is part of the reason oxalate problems are so often missed. Imaging is relatively good at catching stones when they form or kidney dysfunction once it’s advanced, which has reinforced the assumption that oxalates are just a kidney problem.
Experimental studies show oxalate can trigger oxidative stress, mitochondrial dysfunction and inflammatory signaling in cells beyond the kidneys—mechanisms that could affect the nerves, connective tissue, bladder lining and gut lining. Yet because these effects tend to be scattered, slower to develop and harder to image than kidney stones, they fall outside mainstream medicine’s diagnostic framework.
Nephrology “owns” oxalate because stones are visible and acute. Everything else—fatigue, tendon pain, bladder irritation, neurological symptoms—gets routed into other specialties, where oxalates are rarely considered as a cause. The result is the potentially widespread problem of silent, slowly accruing damage.
“You can have absolutely no symptoms and be filling your body with oxalates,” says Norton.
Medicine already knows oxalates can deposit far beyond the kidneys—it just tends to acknowledge this only rarely. In primary hyperoxaluria, a genetic condition in which the body massively overproduces oxalate, researchers have long documented systemic oxalosis: the accumulation of calcium oxalate crystals not only in the kidneys but in the bones, joints, skin, blood vessels, heart tissue, retina, nerves and endocrine glands. In this condition, oxalates become embedded in bone marrow, connective tissue, heart muscle and blood vessels, sometimes years before kidney failure becomes obvious.8
This research establishes a critical biological fact: When oxalate levels rise high enough, the body doesn’t confine damage to the urinary tract. The kidneys are simply the most obvious place to see it.
There’s also compelling evidence that oxalates affect other tissues. Case reports in the medical literature have found calcium oxalate crystals in joint fluid associated with inflammatory arthritis, suggesting its role in unexplained musculoskeletal pain.9
More compelling than the studies are the hundreds of testimonials of people who experience relief—not just from kidney stones but from a wide range of chronic conditions—when they try reducing oxalate-heavy foods in their diet.
Arielle Ford, 73, a writer and spiritual teacher known for her best-selling books on relationships and personal growth, struggled for years with inexplicable on-and-off bowel issues. For months she had growing concerns about frequent bouts of diarrhea even though she ate mindfully—lots of almonds and sweet potatoes were on the menu, along with leafy greens in smoothies and a popular protein powder.
She happened on Sally Norton’s book and was surprised to learn about oxalates. But “it all made sense,” she says. “Everything I believed was good for me was actually hurting me.” She started cutting her daily doses of oxalates, particularly from protein powder, sweet potatoes and the one that surprised her: dark chocolate.
“Within two days I started to notice a difference,” says Ford. The diarrhea stopped almost immediately. Overall, she says, reducing her oxalate consumption has been “life-changing.”
Hanna, a lifelong vegetarian in her 20s, had suffered kidney stones since childhood along with tendon pain, sleep troubles, urinary tract infections and grinding fatigue. Doctors found no clear cause.
After attending a free workshop by Sally Norton, she reduced high-oxalate foods, and her nighttime “brain twitching” stopped. Her bladder calmed. Her energy returned. She slept through the night for the first time in years.
Debra, in her 50s, endured 13 years of debilitating fecal incontinence (as many as 10 episodes a day) plus nausea, back pain and exhaustion. She had tried every elimination diet. Nothing worked. Her bowel function normalized after just three days on a low-oxalate diet.
Oxalate issues don’t announce themselves with a single telltale sign. They reveal themselves through patterns—in symptoms, in your diet and in how your body responds when you identify the offending foods and remove them.
Many people who benefit from lowering oxalates never have kidney stones or suggestive lab results. The first step is simply paying attention.
Do you eat a diet heavy in spinach, almond products, sweet potatoes, beets, Swiss chard, quinoa, chia seeds, cacao, turmeric, or green smoothies or juices? Do you also struggle with unexplained fatigue, joint or tendon pain, digestive problems, bladder irritation, sleep disturbances or brain fog? Then oxalates deserve a closer look, especially if those symptoms began or worsened after you started eating a “healthier” diet.
Lowering oxalate intake isn’t about rejecting green food, eliminating vegetables or chasing another dietary trend. It’s about listening to your body and allowing for differences: What seems to be tolerated by one person may eventually overwhelm another.
“If something you’re eating every day is making you feel worse,” Norton points out, “then that’s important information.”
A low-oxalate diet is not a prescription or a promise. It’s an invitation to experiment and to give your body the chance to show you how it feels when the load has been lightened. Sometimes feeling better doesn’t require adding the next superfood. Sometimes it begins with taking one quietly irritating ingredient off the plate.
“All hell broke out when I started juicing almost two years ago,” Val.Kyrie, a commenter on YouTube, noticed. “Have been trying to heal my gut and now joint pain ever since.”
“For several years I saw countless urologists for this horrible burning bladder I had,” remarked talk2deb. “No infections ever. They had no answers. It turns out the green smoothies (spinach) and drinking almond milk was the cause. I stopped all that and began living again.”
As with everything, the poison is in the dose. Oxalate-rich vegetables are best cooked rather than eaten raw, and it’s wise to moderate your intake of high-oxalate nuts and fruits. Taking a magnesium citrate supplement with your food can also help, as it binds to oxalates, making them more soluble and reducing the risk of forming hard kidney stones.
The human gut is equipped with a special bacterium called Oxalobacter formigenes whose “job” is to break down oxalates in the colon—an especially useful function for a microbe.
But because of rampant antibiotic use, processed diets and high-oxalate eating itself, it’s estimated that only about 35 percent of adults in the US and UK still have it.1 That means more than half of us can’t efficiently break down oxalates the way we’re meant to.
Studies show that supplementing with O. formigenes reduces oxalates in the body.2 The bacterium has been isolated from the gut of sheep, but it’s not yet widely available in probiotic supplements.
A simple experiment often tells you more than any test: Reduce your consumption of high-oxalate foods and observe what happens in your body.
Sally Norton insists, “You’re not trying to cut oxalates to zero. That’s impossible.” The goal is to limit the huge or repeated loads that overwhelm the system.
Keeping in mind kidney specialists’ suggested range of 150–200 mg of oxalate per day, below is a list of the top 10 high-oxalate “health” foods to keep an eye on.
Rather than aiming to cut all oxalate-rich foods from your diet, start by removing the biggest daily sources (for many people, spinach and almonds). Swap rather than subtract. Here are a few common replacements:
Spinach → arugula, romaine, iceberg, bok choy, kale, collards, mustard greens
Almond milk → dairy, coconut milk
Almond flour → coconut flour, rice flour, potato starch
Sweet potatoes → squash, pumpkin
Chia → flaxseed (moderate), gelatin, psyllium
Quinoa → millet
When you do eat oxalate-containing foods, pair them with calcium-rich foods, which can bind the oxalate in the gut for a swift exit. This also lowers your calcium absorption, so be sure to eat more calcium-rich foods, too.
You can also supplement with magnesium citrate, which binds with oxalates.
Another tip is to soak and cook high-oxalate foods rather than eating them raw. Soaking allows some of the soluble oxalates to leach into the water, and boiling further reduces their content, research shows. For best results, discard the soaking or cooking water and rinse the food before eating.
Anything that irritates the gut lining increases absorption of oxalates into the circulatory system, where they can distribute anywhere, settle in and cause inflammation. These are some examples:
NSAIDs alone can set up a perfect storm, says Norton. “Over a third of NSAID users have intestinal ulcerations, risking hyperabsorption of oxalate.” Research shows they can cause gut permeability in as little as 12 hours.
The trouble with oxalates is that they don’t simply pass through the body like fiber. They readily bind to minerals—including calcium (most common), magnesium and iron—to form jagged and insoluble oxalate crystals.
“Calcium oxalate does not play nice with the body,” Dr Benjamin Bikman, a professor of cell biology and physiology at Brigham Young University, says in his online lecture on oxalates. He compares the crystals to “tumbleweeds with thorns rolling through the intestines” on their way to be excreted, potentially scratching the intestinal walls.
When forming in the kidneys, these crystals lump into excruciatingly painful stones. Oxalic acid makes its way into the blood and binds with calcium and other minerals, becoming very troublesome and causing inflammatory reactions wherever it goes—even in circulating immune cells.1
Oxalates are known as “antinutrients” because when they bind to critical nutrients in the body, like magnesium, which regulates hundreds of biochemical reactions, they block these minerals’ actions, causing deficiency effects.
“Oxalate ions are mineral snatchers robbing us of the minerals in foods. As a result, a high-oxalate diet is inherently mineral deficient, especially in calcium and magnesium,” says Norton.
Prof. Bikman says they also particularly bind to non-heme iron (the kind of iron in plants), which is why vegetarians are at especially high risk of developing anemia.
Beyond these issues, Norton emphasizes that once oxalate crystals get into circulation, they can irritate tissues, stress the liver, accumulate in bones and glands, and, in susceptible individuals, crystallize into sharp microscopic shards that can settle anywhere, not just in the kidneys. They can trigger inflammation, disrupt cellular energy production and interfere with the very metabolic pathways we rely on to feel alert, resilient and stable.
“Oxalates are messing with a lot of us in a lot of ways,” she says.
What do you think? Start a conversation over on the... WDDTY Community
Great news! Discounts are available based on your cart total. Check the details below:
