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The Damaging Effects of Oxalates on the Human Body

Analysis by Dr. Joseph Mercola Fact Checked

Story at-a-glance -

  • Oxalic acid or oxalates are very tiny molecules that bind minerals like calcium and form crystals. It is found in a variety of seeds, nuts and many vegetables. It’s only two carbons and four oxygen molecules. It’s a highly reactive compound that is attracted to positively charged minerals
  • Oxalates not only can cause kidney stones (calcium oxalate kidney stones) but also may be responsible for a wide variety of other health problems related to inflammation, auto-immunity, mitochondrial dysfunction, mineral balance, connective tissue integrity, urinary tract issues and poor gut function
  • Oxalic acid can harm glandular function, connective tissue function, neurological function and the function of the tissues of excretion, particularly the kidneys and bladder
  • Having a damaged gut lining will increase your absorption of oxalates. An inflamed or damaged gut lining is a very common problem, thanks to frequent antibiotic use and the presence of a number of chemicals in our food supply, including glyphosate. Other plant compounds such as phytates and lectins (such as gluten) can worsen gut health and exacerbate the impact of oxalates
  • Tissue destruction, fibromyalgia and autoimmune diseases such as rheumatoid arthritis and lupus are all issues that can be related to oxalates

Sally Norton,1 who has studied nutrition and has a graduate degree in public health, is one of the leading experts on oxalate poisoning — a topic you don’t hear much about. Chances are you may never have heard about oxalates, or have any idea why they might matter.

As is often the case with experts in any health field, her expertise is an outgrowth of her personal struggles with health problems that didn’t respond to more conventional treatments, including healthy living (Norton was a vegetarian for 16 years).

“Like so many other people who are now discovering this, I was the kind of person who, no matter what I did, I could not create the vibrant robust health that I felt that I wanted, that I felt was intended for me to have.

It was just perpetual frustration, which is kind of amazing because the more you try to be healthy, the less it works — even when you’ve got a degree in nutrition from Cornell University and a degree in public health.

I worked in integrative medicine and knew all the holistic and complementary healing modalities … Here I was, the health expert who was not healthy …

The Vulvar Pain (VP) Foundation started educating people 25 years ago and making a big effort to get foods properly tested to know about oxalates in food because the story here is that we’re eating foods that are full of a toxin called oxalate …

We’re not paying attention to how this chemical’s affecting our physiology … [Oxalate] is a natural chemical that plants make, and we even make oxalate in our own metabolism.”

Chances are, if you have heard of oxalates, you’ve heard of them in relation to calcium oxalate kidney stones. A vast majority of the scientific information available on oxalate refers to this. However, while it certainly contributes to kidney stones, it can also have other detrimental health effects.

Interestingly, from the 1850s through the early 1900s, oxalate poisoning was well-recognized. Back then, it was referred to as oxalic acid diathesis. It was known to be a seasonal problem that got worse in the spring and summer, when fresh greens were available, when people’s oxalate consumption would go up.

Unfortunately, it has since gotten lost and left out of clinical science. As noted by Norton, there’s scientific evidence showing oxalic acid can harm glandular function, connective tissue function, neurological function and the function of excretion routes, particularly the kidneys.

Oxalate 101

Oxalic acid or oxalates are tiny molecules found in a variety of seeds, nuts and vegetables. It’s only two carbons and four oxygen molecules. It’s a highly reactive compound that is attracted to positively charged minerals. Norton explains:

“Calcium has a particular love of oxalate, and vice versa. The two of them seek each other out quite easily. We often see very abundantly the calcium oxalate form of oxalate. We see it in the plants. The plants form crystals and have the smaller individual ions and nanocrystals.

But they do form these bigger constructions, these kinds of plant pyramids, rocks and sticks and diamonds and things that the plants make, probably deliberately for many … plants are making use of oxalate for self-defense.

In the body, you’re going to see these other forms … A molecule that has less strong a bond — potassium oxalate, sodium oxalate and so on — those are the soluble forms. When you see oxalate in nature, you see the big calcium oxalate crystals — that’s the same thing that the kidney stone is made of. The major ingredient of the classic kidney stone is oxalate.

Unfortunately, in our parlance in medicine, we think of it as calcium … We just generalize to calcium because there are multiple types of calcium stones. But in the case of oxalate stones and oxalates causing calcification in the body, the oxalate part gets sort of dropped.

Medicine is not taught that you need the substrate to make a kidney stone. You need to provide enough oxalic acid or oxalate, soluble oxalate, the potassium oxalate, the sodium oxalates and so on. You can provide enough of that to perform this calcification in the kidneys and elsewhere in the body.

The plants that we’re eating have these oxalate crystals. The big ones just cause abrasion … They’re very small, but at the cellular level they’re quite big and abrasive. They just cause mechanical damage …

These soluble oxalates are the ones that easily — because they’re so tiny — pass through in between cells. Just with passive transport, we end up absorbing oxalates. The amount we absorb depends on a lot of factors, especially the health of our digestive tract.

Those of us with any inflammation in the digestive tract are more prone ... to absorbing more of that soluble oxalate and even nanocrystals of calcium oxalate. At least 1% of calcium oxalate from food is also absorbed, in addition to the soluble oxalate.

But you see, soluble oxalate is not content being potassium oxalate. It would much rather be calcium oxalate, iron oxalate or magnesium oxalate. Right away, it starts grabbing minerals. It starts messing with mineral metabolism. It even can create bouts of acidosis.”

Conditions That Can Worsen Oxalates’ Impact

As mentioned, having a damaged gut lining will increase your absorption of oxalates. Most people, in fact, have damaged gut lining, thanks to a number of assaulting compounds and chemicals.

The presence of glyphosate in our food supply is one of these problematic compounds. If you’re not eating mostly organic food, you’re bound to be consuming glyphosate, which can wreak havoc on your gut function, as described in “Glyphosate: Pathways to Modern Diseases.”

Other gut-destroying exposures include frequent antibiotic use, which can lead to various forms of microbiome imbalance, including small intestinal bacterial overgrowth.

Some processed foods contain mucus-destroying emulsifiers. Even a number of naturally occurring plant compounds such as phytates and lectins (such as gluten) as well as the sharp oxalate microcrystals are trouble for gut health. These and other compounds found in foods can worsen gut inflammation and exacerbate the impact of oxalates by allowing oxalates easy entry into the blood stream.

Many of the foods that have become popularized in the modern diet are also high-oxalate foods, which means exposure is higher in general.

High-Oxalate Foods

Examples of high-oxalate foods include potatoes, peanuts, nuts, spinach, beets, beet greens, chocolate, blackberries, kiwi, figs, black beans, buckwheat, quinoa and whole grains. Norton ate a lot of beans, soy, Swiss chard, and sweet potatoes when she was a vegetarian; these are all high oxalate foods. When she cut wheat and soy from her diet, sweet potatoes became a daily staple in her diet.

Eventually, she discovered the healing value of animal foods such as bone broth, but it took many years of painful disease before she made the connection between her arthritis and her favorite plant foods.

Nuts and seeds tend to contain high amounts of oxalates, so any seed is suspect if you’re sensitive. Pumpkin seeds, watermelon seeds, sunflower and flax are among the safest, as they contain lower amounts. Oils and fats, even when extracted from plants, are all low in oxalates.

“When you extract an oil or fat, you do not take with you the oxalates. It could have been from a peanut. The oil’s still low. Olives are pretty high, but olive oil’s low. It’s really simple. It’s not in the animal foods, and it’s not in the oils and fats. But it’s in most things that are seeds,” Norton says.

“It’s also in several green vegetables, mainly spinach, Swiss chard and beet greens. Those are really the bad ones. There are a couple of kales that are not so good.

Collards are kind of medium bad. The mixed greens that people like now … those baby mixes are loaded with little beet green leaves, little Swiss chard leaves, which are high [in] oxalates …

Certain fruits are really high: kiwi … clementine … Anjou pears, guava, figs, elderberries, apricots, blackberries, unripe avocados … Starfruit is so high it’s really dangerous.”

Signs and Symptoms of Oxalate Poisoning

Tissue destruction, fibromyalgia and autoimmune diseases such as rheumatoid arthritis and lupus are all issues that can be related to oxalates because oxalate in tissues trigger the inflammasome reactions of the body’s innate immune system.

“This reactive compound kind of trashes your basic building blocks of connective tissue,” Norton says. Oxalates also cause inflammation and interfere with your body’s natural healing and repair mechanisms that usually happen overnight while you sleep.

Needless to say, this can worsen a wide variety of ailments, and trigger just as many. Norton tells the story of her own health problems, and how she finally identified oxalates as the culprit causing them all.

“Glycoproteins are where the oxalates get stuck on cells. We tend to see oxalates keeping old injuries in place where you don’t fully recover all the way. That’s one symptom. You’ve got things that don’t completely clear up. For me, it was my feet … I was forced to leave school and go get these feet dealt with. I just could not function anymore.

I had surgery. I stayed out of school for four years because I wasn’t getting better … I was getting weird vulvar symptoms, arthritis, fatigue, difficulty focusing and cognitive problems. There are a lot of neurological neurotoxicity [effects from oxalate] that interfere with cognitive function and sleep.

Fast forward years later to 2009 when I learned about the Vulvar Pain Foundation and connected the bout of vulvar pain that I had to my diet. But it took me years more of flipping around with complete disability. I could no longer work … I basically was sofa-bound.

I had to have a hysterectomy … There was endometriosis in there. The ovaries were trashed … and I didn’t recover well from that. My endocrinologist sent me off to this sleep lab because he said, ‘You’re eating great. You look awesome by way of blood tests. But, obviously, you can’t read, function or exercise.’

I was surprised to see that my nervous system was so toxic that my brain was waking up 29 times an hour … I developed irritable bowel syndrome, and then eventually it turned into chronic constipation, which is very common amongst us oxalate-poisoned people.

Part of what’s going on there is those nerves and muscles are almost paralyzed. They’ve lost their control. Their sphincters aren’t working well. The muscle tone in the colon is not functioning well because of this constant stream of oxalates coming …

It looks like you have SIBO, or you probably do, because of all the antibiotics. Of course, … emulsifiers in our [processed] foods are eroding away the mucous layer. The mucous layer is another layer of protection that we’ve lost and increases our absorption of oxalates.”

Eventually, you may develop signs and symptoms that look very much like an autoimmune disease, such as rheumatoid arthritis or lupus. Norton realized she needed to get her gut healthy. The question was how. She’d already tried everything she could think of.

An experiment with a kiwi diet in 2013 finally made the oxalate issue hit home. Her arthritis flared up and she couldn’t sleep from the pain. At that point, it dawned on her that the kiwi — a high-oxalate fruit — and the arthritis were connected.

In about 10 days on an oxalate-free diet, all of her symptoms improved. Six months after that, her feet, which had never properly healed after her surgery, were completely fine.

Lectins and Oxalates Are a Problematic Mix

On a related note, lectins — another plant chemical — can also wreak havoc on your health, and Dr. Steven Gundry, author of “The Plant Paradox: The Hidden Dangers in ‘Healthy’ Foods That Cause Disease and Weight Gain,” strongly believes lectins are at play in many autoimmune diseases. Norton warns that together, lectins and oxalates can “gang up on you.”

“Plants have many other chemicals too. In my research, it looks like the main target of plant chemicals that are aggressive and harmful to us is the gut … Lectins are going to create that leaky damage and make you vulnerable to infection and absorbing oxalates.

Basically, these [oxalate] nanocrystals and ions are the most toxic forms. The bigger ones that later on you can see in … kidney stones, they’re actually less toxic than the little ones.

Nanocrystals are known to interfere with the charge on cells. They depolarize cell membranes and start disabling the functions of membranes, which means your mitochondria are not working. The oxalate slows down the mitochondrial ability to produce energy.

The nanocrystals of asbestos and oxalates have basically the same level of harm. It’s just that we don’t eat asbestos three times a day and call it health food.”

How Oxalates Contribute to Heart Failure

Oxalates can also contribute to heart arrhythmia, heart failure, endothelial disorders or generalized endothelial distress. Endothelial cells are the cells that line everything, including your vascular system. Oxalates floating around your vascular system can do considerable damage, causing irritation and injury to endothelial cells.

“You set up the conditions for vascular problems,” Norton says. “Oxalates are grabbing minerals. It’s taking calcium out of the blood … and probably other minerals as well. It also has the potential to take the place of the normal chelator that would hold iron in your transferrin …

What we see in people who are post-keto, where they’ve been doing the almond bread and spinach smoothies a lot (these are the kind of people who come to me — ex-vegans and ex-keto dieters), they are getting attacks of heart rates of 130, 150. They’re getting attacks of arrhythmia … A few of them get hospitalized and they’re seeing T-wave inversions … In this case, people have stopped eating the almond bread and the spinach smoothies …

Now the body is so ready to be done with the oxalate that’s gotten stuck in all these tissues that it starts removing too much at one time. Then you get localized acidosis. You get effects in the blood. You get effects in the heart rate.

We see this electrolyte disturbance, which involves continued wasting of potassium and other minerals. We have to keep re-adding these minerals. Also, it’s almost like tissue dehydration. I really like to push salt, potassium, calcium and magnesium to help manage this sort of flushing …

Diaphragm hiccups, by the way, are a bad sign … hiccups are a neurotoxicity symptom; the vagus nerve and the whole diaphragm is getting flipped up by being poisoned … The literature … shows that one of the last symptoms before the rats die or the humans die from oxalic acid poisoning is hiccups …”

Dental tartar and even dental caries are other signs of excessive oxalates. I struggled with chronic tartar buildup myself, until I learned it was related to oxalates. When clearing out oxalates you may also experience sinus pain. Your sinuses, eyes, teeth, jaw and salivary glands are all prone to oxalate buildup, as are your fingers, toes, feet and joints in general.

Do You Need to Ditch High-Oxalate Foods From Your Diet?

If you’re eating a lot of high-oxalate foods and are struggling with any kind of chronic health issue that doesn’t seem to respond to other sensible lifestyle changes and treatments, you’d be wise to give a low- or no-oxalate diet a try.

In my own case, I was eating a lot of sweet potatoes because they’re a good source of “healthy” carbs, but they are also loaded with oxalates. All potatoes are. There is no potato that’s not high in oxalates, so get rid of the potatoes. Norton offers the following advice:

“Turning this around, you have to make a decision that you’re willing to walk away from group think because everybody around you thinks that plants are so great and you need the spinach smoothies … If you’re willing to get some facts that are science-based, then I’ve got a lot of free information on my website.

The way I understand one of the major mechanisms is this something called a trigger-maintenance theory of the oxalate accumulation in the body. The body is really smart. It’s holding onto oxalates because it’s trying to protect you from that heart arrhythmia and all that vascular damage.

The nonvascular system … the body is willing to sacrifice in order to keep the vascular system well … If you’ve got too much oxalate in your blood, the other cells will deliberately hold on to it as a temporary deal …

The body’s holding on to oxalate is meant to be temporary. Every tissue that’s holding oxalate so wants it to be gone. You give it that opportunity when you stop eating oxalates. But there can be so much already onboard. If that stuff starts moving at the same time, you could release oxalate from tissues at a [toxic] level … We’ve got to be careful about how quickly and how we go about moving [oxalate out] …

There are simple things you can do to start lowering your oxalate. Pick the foods that you don’t need in your life and then eventually get down to the chocolate and cut that too …

On my website you can get a beginner’s guide2 that explains the basics and has a graphic that shows that your spinach smoothie is 20 times what your level of oxalate should be on a whole day’s intake. It has a list of the safe bet foods and the worst offender foods that you’ve got to start cutting back on and then eventually eliminating altogether …

The two main causes of disease are toxicity and nutrient deficiency. Oxalate is causing both … You’re losing both B-vitamins and minerals. It’s very toxic. It is a poison. It’s fundamentally messing with the basics of metabolism that allows tissue recovery, repair, [that] allows growth and flourishing.”

The Carnivore Elimination Diet

Norton has for several months now been doing the carnivore diet as described in “Health Effects of the Carnivore Diet,” which features my interview with Dr. Paul Saladino. Norton discusses her transition:

“I kept seeing allergy, intolerance and colon intolerance to a lot of plant foods. I had already worked my way down to eating lemon juice because citric acid … helps weaken in bonds of the [oxalate] crystals and make them quite easy to come apart.

Citric acid protects your kidneys and is a great way to dissolve kidney stones. A half a cup of lemon juice a day and a low-oxalate diet will help your kidneys release all this oxalate painlessly. You just start peeing out all your kidney problems without pain.

I was using a lot of lemon juice, four or so lemons a day, and eating coconut products and coconut water, often from fresh young coconuts, sometimes bottled or dried coconut, and very little else for like a year. It really does help the colon repair and recover. It’s such a nice elimination diet.

April 1, 2019, I dropped the lemons and a few more supplements I was taking, like vitamin E, and dropped the coconut products … I went full carnivore.

I, myself, think that the mitochondrial and metabolic damage that’s happening from the oxalates is also being promoted by PUFAs, the polyunsaturated fatty acids, which I did not have a lot in my diet.

But some of us still need some sugars in the diet to keep the mitochondria happy. I’m back to using some maple syrup and some mangoes and a little bit of carbs to keep my legs from cramping up with low muscle glycogen.

I still love a high-fat diet. I eat a lot of beef fat and pork fat. I really enjoy a meat-centered diet. I think it’s a fabulous elimination diet that can help us. Then figure out how to bring back into the diet, as much as you wish to, low-oxalate foods like lettuce, apples and coconut stuff and some rice, some blueberries … things that you may want in your diet.

There’s a whole lot of vegetables in the cabbage family that are low in oxalate, if your digestive tract likes them, [that] … have resistant starch in them and can be useful … Transitioning from a high-oxalate diet to a low-oxalate diet, maybe even all the way down to the carnivore-style elimination diet, needs to be gradual.

Because if you create a big microbiome die-off, you’re just going to feel sick from that as well. When the oxalates start coming out, that makes you feel sick. That’s another reason why we need supplements.”

Recommended Supplements for Oxalate Poisoning

Supplements recommended by Norton for those struggling with oxalate poisoning include calcium citrate, potassium citrate, magnesium citrate and potassium bicarbonate. These are all simple mineral salts that you can easily buy in bulk powders, which I recommend doing as readymade capsules contain amounts that are so low you’ll have to swallow a whole handful of pills to get the dosage you need.

If you dislike the taste of potassium bicarbonate (which has a flavor reminiscent of baking soda), you can purchase large empty capsules and make your own. Natural unprocessed salt (such as Himalayan salt) is another important “supplement.”

“Some people go through these waves of feeling ill again as their body starts pushing out oxalates because, when you stop eating oxalate, that doesn’t fix your oxalate problem in the short run, because you’re still full of oxalates ...

It’s just that the acute phases that were occurring post-meal aren’t there anymore. But you’re going to have some other phases that are often circadian in nature where you have waves of not feeling good.

We want to be aware that some of what’s going on there is a form of acidosis … The combination of lemon juice and bicarbs — about a quarter cup of lemon juice and about one-eighth teaspoon of sodium bicarb and one-eighth teaspoon of potassium bicarb — makes a lovely Alka-Seltzer Gold, made with natural citric acid …”

Again, any changes you make, whether removing food items high in oxalate or adding supplements, make sure you do it slowly and incrementally. If you have a lot of oxalate in your body, too-rapid a change can shock your already fragile system, causing you to get worse rather than better.

Over time, work your way up to 1,200 milligrams of calcium citrate, about 400 to 500 mg of magnesium and 2,500 – 4,000 mg of potassium per day. The purpose of the calcium citrate is to help release oxalates from your tissues, so when looking for calcium citrate, make sure it does not have vitamin D in it, as the vitamin D encourages absorption of oxalates.

“The bicarb is wonderful because it’s not citric acid [which, for some, can irritate the gut]. It is also alkalizing, as is the citric acid and the minerals. All of this helps with alkalization. You’re replacing the minerals. You’re also providing it citric acid, which protects your kidneys and other tissues from oxalate accumulation and damage.

They’re really helpful. You want to take as much as you can tolerate, because the more the merrier when it comes to the minerals. I think general liquid mineral for a broad spectrum is really good, [and] taking [natural unprocessed] salt to help pull hydration and pull potassium back into the bones and the muscles.

A lot of us, if you get any muscle numbness, like fibromyalgia pains, that’s the potassium deficiency showing up in the muscles, where they end up in chronic rigor and you get hypoxia from the poor circulation going on there.

Once you’ve got enough potassium that will disappear completely in about five or six weeks … I have salt and potassium bicarb, potassium citrate always in my drinking water … I drink it all day long, all the time ...”

If you don’t want to drink it throughout your day, Norton recommends taking a third of your daily dose at bedtime, as this is when your body is repairing and recovering and needs these nutrients most. Take another dose in the morning, and a third dose with a meal. An additional dose can be taken if you’re having an episode you think might be related to oxalate release.

More Information

Norton currently has a book in the works. Until then, the best place to find more information is her website, SallyKNorton.com. There you can find symptom lists, guidance on oxalate-elimination, low-oxalate recipes, free articles and additional interviews and talks,3 along with more details on the science behind oxalates’ devastating health effects.

For a quick look at your own intake of high oxalate foods and the signs of oxalate-related health issues, check out Sally’s Symptom and Exposure Inventory, HERE.

“If you work your way through the various tabs on my site, you will get a huge education there,” Norton says. “And then work your way … through my blog … There’s enough reading there. You’ll be busy for a while. That will really help a lot.”