Health Dangers of Oxalates

Health Dangers of Oxalates

Health Dangers of Oxalates

Health Dangers of OxalatesIn our look at the Health Dangers of a Plant-Based Diet we turn to oxalates. These are especially troublesome to the “health conscious” who have large spinach and kale salads topped with almonds and sesame seeds. They think they are eating healthy. But they are flooding their body with oxalates. Here we’re going to look at the health dangers of oxalates.

Health Dangers of Oxalates: Seed Strategy

Plants use great strategy with their seeds.

Plants lace their seeds with natural pesticides to deter pests and predators. The sharp oxalate crystals can prick a predator’s mouth thereby playing a role in plant defense. [rr]

Plants also load their seeds with nutrition for the baby plant. They use oxalate as a way to store calcium for the baby offspring.

When seeds start to germinate they split off the oxalic acid which frees the calcium for the baby plant.

Health Dangers of Oxalates: “Spinach Prick”

Oxalate Accumulation

While oxalate is useful as a calcium storage mechanism for plants, it’s toxic to humans in acute and chronic amounts. If you eat too much oxalate you die. Simple as that. But often oxalate toxicity is more insidious. [r]

Similarly to how phytic acid is a mineral thief, oxalic acid is a magnet for minerals, especially calcium. Oxalic acid grabs calcium and forms calcium oxalate – the main ingredient in kidney stones. [r, r]

These oxalate crystals build up into bigger and bigger crystals. They bioaccumulate. As they accumulate the body deposits these sharp crystals throughout the body – in joints, muscles, and especially the kidneys. [r, r, r, r, r, r]

With oxalate crystals growing and stored throughout the body muscles start aching, eyes, ears, mouth, and throat can burn, and stones form in the kidneys.

“Spinach Prick”

Many people think spinach is a good source of calcium. But it’s a fraud. The calcium in spinach is completely useless. It’s all tied up in oxalate. And this is true for all high-oxalate foods.

In the lab we can measure the calcium content in spinach, but that doesn’t mean it’s available as a nutrient for the body. There is a big difference in the nutrition measured in food and the nutrition that the body can actually absorb and use.

This is where standard nutrition guidelines fail miserably.

If we eat 100% of our RDI (recommended daily intake) of calcium from spinach, but 100% of it is tied up in oxalate, we really got 0% of the RDI. Making matters worse, certain foods can increase the amount of a nutrients we need.

For example, If I were to eat a large bowl of spinach every day for lunch, I would increase my need for certain vitamins and minerals. Processing the high oxalate concentration in the spinach depletes vitamin B6 and likely requires an increased amount of biotin and thiamine in my diet.

Spinach Sabotage

Oxalate isn’t just an antinutrient that depletes calcium and iron, stealing essential vitamins and minerals. It’s also toxic.

Oxalate crystals cause renal damage; they are neurotoxic; they activate the immune system, upset the GI tract, deplete glutathione, and corrode connective tissue (via interference with hyaluronic acid).

Oxalates can impact nearly every bodily system. [rrrrrrr, r, r]

  • They can cause neurological symptoms which disturb sleep and adversely affect coordination, memory, learning, and concentration.
  • They cause pain via mast cell degranulation and histamine release.
  • Mysterious vulva pain, fibromyalgia, and carpal tunnel syndrome can all have oxalates causing or worsening the symptoms.
  • Increased calcium excretion and increased oxalic acid excretion ride hand-in-hand and are linked with osteoporosis.
  • Common practice for autism treatment is the elimination of oxalate-containing foods (as well as gluten, casein and soy).

Oxalate Absorption

Absorption of oxalate differs among people. For some, oxalate is largely broken down in the gut and eliminated without causing too many issues. In others, a large percentage of consumed oxalate is absorbed.

Someone with a compromised, “leaky gut,” can see increased absorption of oxalate.

Not only does “leaky gut” allow more oxalate to get in, oxalate can be implicit in exacerbating leaky gut. The needle shape of oxalate crystals can perforate mucus membrane cells damaging the gut and increasing “leakiness”. [r, r, r, r, r, r]

Health Dangers of Oxalates: High-Oxalate Foods

It’s not only spinach pricks that can hurt you.

Many of the cruciferous vegetables like kale, cauliflower, and broccoli have high concentrations of oxalate.

Other culprits include chocolate, most nuts (especially cashews and almonds that are popular among the health conscious) and seeds like sesame and poppy seeds. [rr, r]

One of the worst offenders is soy. I remember when I was soy stupid – clueless that my soy protein shakes were loaded with oxalates.

Berries and beans. Potatoes and sweet potatoes. Okra. Swiss chard. Anything in the buckwheat family like sorrel. All high in oxalates.

Sorrel is actually worse than spinach and kale. And for some reason it is popular in fancy restaurants. There is this case report of a man who ordered sorrel soup for dinner. Two hours later he died in the hospital from acute oxalic acid poisoning. [r]

The man had poor metabolic health. He was obese and diabetic. And this poor metabolic health further impairs the handling of oxalate toxins. Yet, today we encourage obese diabetic patients to eat diets that are high in oxalates.

Health Dangers of Oxalates: Insidious Impact

Like other plant toxins, we don’t know (with any degree of accuracy) the frequency and degree of harm from oxalates thanks to a general lack of awareness. It often takes a bioaccumulation to the point of acute kidney injury until a healthcare practitioner even considers oxalate as a potential culprit. [r, r]

Sometimes patients with oxalate problems are asymptomatic until they find themselves trying to pass a kidney stone.

Sometimes mysterious lingering pain gets diagnosed as fibromyalgia or carpal tunnel syndrome without any knowledge as to why the pain is occuring.

Clearing the Crystals

Sometimes oxalate toxicity symptoms present when eating high-oxalate foods. But often they don’t. And sometimes symptoms don’t present until one stops eating oxalates.

For example, a flare up of pain may be from the release of stored oxalate that’s been consumed over a period of time.

The reason is that you have all these oxalate crystals accumulated in tissues, and now that you aren’t eating them, the body can process out the stores. The tissues start dissolving big crystals down into smaller crystals (and into their ion form) which are what cause much of the cellular damage and pain. But once back out into the bloodstream they can be excreted through the urinary tract. [r]

This process of breaking down and unloading the stored crystals for excretion can cause the same or worse symptoms than when they were originally eaten.

You’ve got to “re-eat” all that spinach.

Health Dangers of Oxalates: What (not) to do

Oxalate damage is from toxicity. It’s not a food sensitivity or allergen. So reversal of oxalate toxicity is a 2-step process:

  1. Stop eating it
  2. Excrete that which is stored up

Unfortunately, there isn’t a good way to determine how much oxalate damage you might have or how well you process them in general. Urine test are unreliable and a biopsy of tissue from the kidney is quite invasive. [r]

It’s also hard to correlate oxalate consumption with symptoms as mentioned (you may be asymptomatic with insidious accumulative damage that doesn’t present until a serious event like kidney failure, or symptoms may only arise after you stop eating them. etc).

The best thing you can do is limit the amount of oxalates you eat.

The major source of oxalates are from plant-based foods. But oxalate is also a byproduct of metabolism.

For example, excess Vitamin C can get converted to oxalate. Just another reason megadoses of Vitamin C might not be a good idea.

Cooking and Cleanses

There’s also a false notion that you can just cook the oxalate out of your vegetables. But this doesn’t work.

Oxalate and oxalic acid crystals are so durable that they are used by paleontologists to determine what people ate thousands of years ago. They aren’t destroyed by heat or cooking.

The one thing that can help is boiling them in water. The soluble parts of oxalic acid that aren’t crystalized yet can leach out into the cooking water. So if you boil your broccoli to mush you can reduce the oxalate concentration by maybe a third. [r]

There are a lot of misconceptions around “healthy” food, perhaps epitomized by the “green smoothie cleanse.” People want to do the right thing, but are often “stabbing” themselves in the foot (or more accurately the kidney).

But a green smoothie “cleanse” is more likely to lead you to needing an oxalate cleanse.

[NOTE: You can now access the complete “Health Dangers of a Plant-Based Diet” series here]:

Resources [r]: Many resources were used in the research and writing of this article. It’s often impossible for me to cite everything that has helped draw the conclusions presented. But I wanted to make a special note on the “Journal of Evolution and Health” Volume 2, Issue 3, 5/2018 and it’s references that were especially helpful. This is a great place to start if interested in learning more about oxalates.

18 Replies to “Health Dangers of Oxalates”

  1. You write ” Kale/ broccoli has a high concentration of oxalate” Yet, The Harvard School of Nutrition lists the following:
    “Broccoli. 1/2 cup 1 mg oxalate” and ” Kale( chooped) 1 cup 2 mg oxalate” These two foods are listed under catagor “Good Choices”. FDo you consider these concentrations of oxalate to be high?

    1. It really depends.

      How much do you eat? How often?
      How is your gut health? Immune health?

      Many factors influence ill effects of oxalates.

      A little every day can turn into a lot. And it can often be quite insidious.

  2. Hi Kevin,
    thank you for another great article. It would be gread if you added means to detox these stored oxalate crystals from our body tissues.
    Thank you!

  3. After switching from spinach because it burnt my skin as if someone was putting a cigarette out on my wrist and a vein in particular, I switched to kale and which gave me foul smelling wee and the symptoms of a urinary tract infection and have now cut both out. At 52 I have sprained my ankle this year, had an infection from a knock on the shin and have shoulder issues and feel either these joint or bone issues are related to oxolates. I eliminated these foods not understanding what the cause/toxicity was but knew there was some compound that was the cause which i ate 3-5 times per week and put with many meals including home made curries.

  4. So what happens when your body dumps them? I’ve just gone through a dump I suspect taking a supplement that encourages that (l-ornithine?) and have been experiencing lots of bladder and female pain. Do the crystals just embed themselves and stay there? Will they ever dislodge and leave? What can I do to make the pain go away?

    1. The body can start dissolving/eliminating them when you stop eating them.

      As far as pain management – you can take an analgesic, but personally I try to avoid these.

    2. Lola, I have the same issues – I.C and vulvodynia, they are nasty! I am on week 5 of carnivore, but I have kept butter in, as of today I am removing butter as I think It is one last trigger. I hope that we get relief soon!

  5. What do you think about calcium citrate supplementation to help rid the oxalate? I don’t like to supplement calcium because of the risk of it being absorbed in soft and cardiac tissue, but I’m willing to do it temporarily if it might help. I’ve been suspecting oxalate is a big cause of my degeneration over the last 5 years. I live a very healthy lifestyle but have practically been crippled with degenerative discs, causing me to have 2 surgeries, and 2 rotator cuff tears resulting in surgeries. My joints and muscles are always in pain. Better when I eat Keto, but not that much. Thinking about giving carnivore a try. I ate lots of spinach over the past decade, I mean LOTS! I may even need the calcium if I’ve just been chelating it out of me with all the oxalate over the years. Maybe it would actually help with repair if I only used it temporarily. Thoughts? Thanks!

    1. I don’t think it’s necessary and like you mentioned, may do more harm than good.

      I’d definitely lay off that spinach though.

  6. I have always been susceptible to kidney stones. In addition, the last 2 years I have suffered horribly with IBS including fecal incontinence. I had a long flight scheduled and fasted in preparation to avoid any accidents. You guessed it – became very dehydrated and developed kidney stones. Seeking relief from the pain/hoping to prevent future stones, I researched and stumbled across the Harvard oxalate content in foods spreadsheet and eliminated all high and even moderate oxalate foods. Surprisingly, in LESS THAN A WEEK my IBS symptoms disappeared. (took a while to pass the kidney stones but no pain or symptoms there after about 2 weeks). Vulva pain, which I was told was “normal for your age” has also disappeared, a salivary gland that was always swollen shrunk to normal (turns out oxalates can cause salivary stones as well) and I was able to discontinue my ADD medicine. Losing weight as well! I “slipped” over Thanksgiving and became very ill very fast. Wheat is the worst for me as are potatoes. Whenever I am tempted to “cheat” I think of the pain of passing those stones. If that doesn’t work I remember two words: “fecal incontinence.” Thank you so much for your blog and advice! I feel so bad for all the folks needlessly suffering from kidney stones, IBS and other issues when simple dietary changes could change their life! (Link to spreadsheet listing oxalate content in dozens of foods –

  7. You can add Arthritis and Autism to the list of disorders as the oxalates bind to cobalt, sodium, potassium, magnesium, zinc and calcium. Try a topical ointment of coconut oil infused with ginger oil to help decrease the pains associated with detox from oxalates.

  8. Hello Kevin, I’ve read that too much protein can also worsen oxalate problems. Can you supply a more comprehensive list of what and what not to eat please?

    1. I think research evidence points to increased protein not worsening oxalate problems as the catabolism of diet-derived amino acids is not associated with an increase in endogenous oxalate synthesis.

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