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The Demonization of Dietary Oxalate Has Begun

From kidney stones to vulvar pain, oxalate has had a storied journey on the path to being framed for all diseases by one would-be expert

You could call it The One True Cause of All Diseases Club. Admission is based on whether or not you have a mustache and are willing to twirl it a lot. A volcano lair and a love for petting white cats on your lap will also do. Over there, you will see sugar and aspartame in a surprisingly tight embrace. Monosodium glutamate is looking at them longingly, while gluten still acts like the cock of the walk. Lectins might be underage, but they managed to squeeze in with a fake mustache.

It’s getting to be a crowded field. The latest member of The One True Cause of All Diseases Club? Oxalate.

You will hear oxalate demonized by Sally K. Norton, who has just published a book about her theory. It’s called Toxic Superfoods: How Oxalate Overload Is Making You Sick—and How to Get Better. Publishers Weekly calls it “informative.”

Norton believes that the push for “superfoods” was wrong. I agree with her on that, but she claims that many of these so-called superfoods are actually toxic to us because of the oxalate they contain, and she recommends a low-oxalate diet.

Too much oxalate can lead to excruciatingly painful consequences, but its crowning as disease kingpin by Norton is based on nothing more than wishful thinking and some questionable research into vulvar pain.

Blood out of a stone

Oxalate plays an important role in kidney stones. When certain minerals supersaturate our urine, these minerals form crystals that stick to the lining of our urinary tract. The crystals grow into what are commonly referred to as “stones,” and these stones can cause bleeding and tremendous pain. The vast majority of these stones—70 to 80%, to be exact—are made up of a mineral called calcium oxalate.

Oxalate is a molecule made up of two carbon atoms bound to each other, with each carbon also linked to two oxygen atoms. It serves many functions in microbes and plant life, although our own bodies have no use for it. In the early 1800s, oxalate was commonly utilized in England as a laundry cleaning agent, which proved toxic to many workers in that industry. It was also sometimes ingested by accident due to its resemblance to Epsom salt, which at the time was recommended to treat a number of ailments.

Even if you’re not a 19th-century English laundry worker, there is oxalate to be found in your body. Some of it comes from the chemical reactions in the processing of glycine, hydroxyproline, and vitamin C in the body, while you get the rest from the food that you eat, with some food items like spinach, rhubarb and potatoes being particularly high in oxalate.

Given that most kidney stones are made of calcium oxalate, the idea of a low-oxalate diet to prevent the recurrence of these particular kidney stones makes intuitive sense. The reality, however, is a lot more nuanced than that. According to UpToDate, an evidence-based clinical resource, there is little data on stone recurrence, and what little data there is shows that the odds of a second episode of kidney stones depends on many factors. Even the amount of oxalate we consume in our food is only a modest risk factor for getting kidney stones in the first place. Some genetic predispositions seem to influence our personal risk, although even here our understanding of the many genes involved is quite rudimentary.

There is still disagreement over whether a low-oxalate diet to prevent further episodes of kidney stones is worthwhile. Some say no and argue that its effectiveness has been poorly studied and that it may invite worse health down the road. Foods are not made up exclusively of oxalate; they contain a number of different chemicals that all play different roles in our health, and banishing them from our diet can lead to deficiencies and to unintended consequences.

Others, however, point to guidelines from expert medical societies that seem to endorse a low-oxalate diet to manage kidney stones but even there, nuance is called for. The American Urological Association does not recommend a low-oxalate diet, but rather the limited intake of food high in oxalate, which is not the same thing. Portion control and avoiding items like spinach and potatoes that contain very high levels of oxalate might be enough and it makes for a less restrictive diet than simply sticking to food low in oxalate. Besides, their guideline is described as “expert opinion,” not as a recommendation based on strong scientific evidence. Their recommendations, by the way, also include drinking enough fluids, limiting sodium intake, and getting enough calcium, which are based on scientific evidence. Meanwhile, the Canadian Urological Association’s guideline does not endorse a low-oxalate diet for kidney stones.

Oxalate in the diet is thus not the ultimate boogeyman we might assume it is for kidney stones, even though oxalate has clearly been shown to be crucial to the formation of most of these stones. But in the 1980s, someone wondered if oxalate had something to do with pain in the vulva, opening the door to Sally K. Norton’s claim that we should avoid this molecular scoundrel.

The medical detective

In 1982, a woman named Sherry developed pain in her vulva after her second child was born, pain she described as someone putting out a cigarette on her genitals. She spent years seeking treatment to end this pain, often being dismissed. She underwent surgery to remove the labia where she could feel the pain, to no avail. She ended up diagnosed with suicidal depression by her psychologist, who sought ideas on how to help her patient from the urologists and OB/GYNs in her building. No luck.

This therapist then remembered that the spouse of another psychologist working with her was a bit of a “medical detective.” His name was Clive Solomons and she reached out to him for advice.

It is unclear to me what Solomons’ exact qualifications were. He is often described as a biochemist with a Ph.D., not as a physician. He was the research director for a consulting firm called Scientific Connections, and an EPA document lists him as a professor and director of orthopedic research at the University of Colorado Medical Center, which was unwilling to answer my question about his credentials. Solomons retired in 2006 and passed away six years later.

But back in the mid-1980s, Solomons went on a hike in the mountains of Colorado, bringing with him a book on medicinal plants. Leafing through it, he read a description of the sensation one felt by putting a particular plant in one’s mouth that sounded a lot like the vulvar pain Sherry had carefully described to her therapist. Solomons wondered if there was a connection there.

He came to think that a catheter that had been inserted into Sherry’s body right after the delivery of her baby had injured her vulva and made it sensitive to the oxalate her body was getting rid of, the same molecule found inside that mountainside plant from his book. He measured the amounts of oxalate Sherry’s body was excreting in her urine and proposed to her that she abide by a low-oxalate diet. According to the case report that Sherry’s psychologist and Solomons went on to publish, it is unclear if the diet helped, but supplements of calcium citrate, which are said to help prevent the oxalate from crystallizing and causing problems, were associated with improvements. Stopping them brought the pain back on two occasions, and the pain went away when the supplements were started again.

Solomons pivoted his research career to exploring the role of oxalate in vulvodynia, a chronic and unexplainable pain in the vulva, but several caveats are in order. Critics of Solomons’ have noticed that he was charging money for women to take part in his studies, which is unorthodox, and was directly selling them nutritional supplements. After Sherry’s pain went away and her case was published in the medical literature, Solomons’ subsequent research was not published in the same literature. Instead, one of his patients started the Vulvar Pain Foundation which worked closely with Solomons on his research. The foundation advocates for a low-oxalate diet to treat pain in the vulva, even though it is not an evidence-based intervention for vulvodynia. (UpToDate does mention that some patients find acidic or sugary foods exacerbate their vulvar pain, but that excessive excretion of oxalate in the urine has “not been implicated as a cause of localized vulvar pain syndrome.”)

Yet, it is this Vulvar Pain Foundation that inspired Sally K. Norton to focus on oxalate.

A recipe for a new wellness trend

In the first chapter of Toxic Superfoods, which is already listed by Amazon as the #1 Best-Seller in their “Preventive Medicine” section, Sally Norton blames oxalate for seemingly every symptom and disease the human body can experience: digestive distress, inflamed joints, chronic skin issues, brain fog, mood problems, stiff neck, carpal tunnel syndrome, pain that never resolves, eye floaters, reflux, shortness of breath, yeast infections, clumsiness, headaches, anxiety, panic disorder, vision and hearing loss, and dementia. She also claimed to believe, on a recent podcast, that osteoporosis is late-stage oxalate toxicity. Essentially, she is attempting to single-handedly rewrite the medical books.

Norton was experiencing what she calls “genital burning” when she came across the Vulvar Pain Foundation and their low-oxalate diet, courtesy of Clive Solomons. This diet led to “multiple personal miracles,” she writes in her book. “I started to feel younger.” Who knew the fountain of youth could be accessed by removing spinach from one’s diet?

On her website, she claims a Bachelor of Science in Nutrition from Cornell University and a Master’s in Public Health from UNC Chapel Hill, though what I found particularly telling was one of the jobs she had held. She spent many years managing a project funded by the then National Center for Complementary and Alternative Medicine (now renamed the National Center for Complementary and Integrative Health). The goal of the project? Integrating so-called alternative medicine in the education of health professions.

It will probably come as no surprise to learn that Norton is also anti-GMO. On her blog, she fearmongers about fake meat, calls lab-grown meat “cancer tissue to be sold as a human food,” and uses the prefix “franken-” from Frankenstein when describing some of the processes used by the food industry.

I don’t know where she gets her “knowledge” that oxalate is a poison that is seemingly causing every possible disease. The webpage where she explains in detail how oxalate causes a range of problems inside the body does not contain any reference backing up her allegations, except for one broken link to a website called Toxipedia. Are there studies investigating a potential link between oxalate and a host of diseases? Sure. This study of nearly 3,000 adults, for example, found a “modestly elevated risk” for cardiovascular disease in people who consumed a lot of oxalate, but the risk disappeared in people with medium or high levels of calcium in their diet. It is possible that high levels of dietary oxalate will clearly be shown in the future to be directly implicated in a specific disease, but the idea that it is the mustache-twirling villain behind everything from dementia to acid reflux to clumsiness is silly. No one thing causes every affliction.

Norton’s website lists low-oxalate recipes, of course, but here’s a recipe I find more helpful. You take one person afflicted by many debilitating health issues and who claims salvation by removing one ingredient that few people know about from their diet. You get them to plant their flag in the ground and start evangelizing about the evils of this ingredient. You make sure they say that diagnosing toxicity from this ingredient is very hard and that doctors can’t even do it, so they can’t be trusted. You promote this newly-minted expert on podcasts that focus on special diets and get them invited as speakers to conferences. You give them a slick website on which to demonize their chosen ingredient. A photo shoot of them running on the beach in pastel-coloured clothes at sunset is a plus. You turn them into a lifestyle consultant, charging USD 500 for a first session and USD 175 for subsequent appointments. And of course, you get them a book deal in which to expound on their boogeyman/panacea combo. Norton seems to be the latest outcome of this recipe. I eagerly await her announcement of a personalized line of calcium citrate supplements.

I predict a bright future for Sally K. Norton and her anti-oxalate crusade, unfortunately. She is already blaming oxalate for “health declines associated with ‘normal’ aging,” according to her book. I can imagine her selling her low-oxalate diet to Silicon Valley entrepreneurs looking for the next anti-aging bandwagon, as intermittent fasting becomes passé.

She has been blessed by the guru of wellness, Joe Mercola, appearing on his podcast twice already. This tells me that we’re not done hearing about how oxalate, despite a lack of credible scientific evidence, has just made a stunning entrance in the crowded hall of The One True Cause of All Diseases Club.

Take-home message:
- Oxalate is a molecule we find in the food we eat and our body also creates oxalate as part of its metabolism, and this oxalate is eliminated in the urine
- While calcium oxalate makes up the vast majority of kidney stones, a strict low-oxalate diet is not typically recommended to prevent the recurrence of oxalate kidney stones
- Sally K. Norton’s book Toxic Superfoods claims that oxalate can cause seemingly every symptom and disease and recommends people stick to a low-oxalate diet, despite a lack of credible scientific evidence to support her allegations


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