Oxalate: The Poison In The Plants You Eat

Oxalate is a naturally occurring, invisible compound found in many kinds of plants and foods. It is an extremely potent toxin that can have devastating consequences when consumed in large quantities. In this article I’ll explore what oxalate is, where it comes from, and how it affects your health.

✅ If you’d like to learn more about Oxalates I can highly recommend Sally Nortons book Toxic Superfoods.

So What IS Oxalate?

Oxalate is an organic acid found mainly in plants, although the human body can also synthesize some. Oxalate comes in two forms: soluble and insoluble. The soluble variety dissolves easily in water, while insoluble does not.

Insoluble oxalate takes the form of crystals, much like tiny pieces of broken glass or needles, that are too small to be seen by the naked eye, but that can have similar effects to broken glass or microscopic needles in the body.

Imagine what broken glass might do floating around in your blood, lodging in tissues, joints or organs, and you have a picture of what oxalate crystals can do in your body.

Oxalates are essential for the growth and survival of many plants, but they’re also their secret weapon. And while oxalates are present in a variety of different food sources, they are most commonly found in high amounts in fruits and vegetables such as spinach, beets, rhubarb, and Swiss chard.

The purpose of oxalate in plants is to serve as a defense against predators. Plants manufacture oxalates to make them less appealing to animals and insects, thus helping to protect the plant from being eaten. In addition, oxalates have been proven to have antimicrobial and antifungal properties, further protecting the plant against disease.

High levels of oxalate in the body can lead to inflammation and disrupt the function of the digestive system.

Oxalate is a powerful toxin, it can cause many health issues, and if you consume too much at once it can kill you. Apparently a lethal dose of this common plant toxin is around 4000mg – or ten cups of spinach.

The Dangers of Eating Too Much

There are many different types of toxins in the plants we eat. These toxins are defense mechanisms used by plants to try to prevent animals and insects from eating them. When we understand that these toxins are the only way that plants can protect themselves; that they, like every other living thing on the planet want to live and reproduce to keep their species going; and that they don’t want to be eaten, then you begin to get the picture.

Plants can not run away, so they need other strategies…

For example beans and legumes contain Lectins.

Cassava (which Tapioca is made from) and bamboo shoots contains Cyanide.

Then there are Solanines and Chaconine which are toxic glycoalkaloids contained in the Nightshade family (potatoes, tomatoes, eggplant etc).

There are also many other toxins made by plants that we commonly eat. If you’d like to know more you can find more information here.

✅ I recommend Dr Gundry’s book about Lectins if you’d like to learn more about Lectins and how they affect your body. It’s an informative read.

Oxalate is Stored In Your Body

However the difference between Oxalate and all these other plant toxins is that when you stop eating those other toxins, they are very quickly gone from your body. This is NOT the case with Oxalate!

When we eat more oxalate in our diet than our body can excrete, it will store the excess to get it out of the blood. This is because too much of this in the blood at one time can be dangerous, and even life threatening.

Your body is always looking after you, doing the right thing to keep you alive!

So Oxalate can be stored almost anywhere in the body – organs, joints, tissues, eyes, skin… This acidic substance will be tucked away with a view to releasing it later when blood levels are low enough, to be eliminated via the kidneys or the digestive system.

The problem is that when we eat a high oxalate diet day and and day out, year in and year out, there is no option to eliminate the excess, and it builds up in the body. Eventually, (for many people this can be after many decades of high oxalate eating), we begin to experience health problems we put down to aging, that may in fact be caused by this toxin being stored in our bodies.

Symptoms of Consuming High Levels of Oxalate

The symptoms of consuming a high oxalate diet can be many and varied. But first, how much is too much? Well the figure provided by Sally is 250mg per day for most people, but for those with leaky gut or some health issues, that number could be lower. That’s not much considering a half cup of cooked spinach is around 450mg and the same amount of cooked chard is about 270!

Depending on what you’re eating each day, oxalate can mount up quickly. When I switched to a carnivore diet in May 2022, and I began to really dig in and learn about oxalates, I realised with horror that I’d probably been close to fatal levels of oxalates many times in my life while consuming my ‘healthy’ daily green smoothies containing usually at least two cups of spinach, two tablespoons of raw cacao, almonds, chia seeds, raspberries and more! And when I consider that my healthy lunchtime smoothies were often on top of a breakfast of buckwheat porridge with raspberries and cinnamon… well it was no wonder my health was gradually deteriorating…

So back to the symptoms of oxalate poisoning. These can be varied and confusing but may include any of the following:

  • Cloudy urine
  • Recurrent yeast infections
  • Pain in muscles, bones, joints
  • Genital pain
  • Tooth pain or gum disease
  • Unexplained skin problems
  • Unexplained vision problems
  • Thyroid issues
  • Kidney stones
  • Irritable bladder or urinary urgency
  • Digestive issues
  • IBS-D or IBS-C
  • Inflammatory bowel
  • Rectal/bowel function problems
  • Unexplained abdominal pain
  • Brain fog, mood problems, neurological issues
  • Tendon problems, tendonitis, bursitis, joint swelling
  • Slow recovery from injury or surgery
  • Low bone density or mixed bone density (some areas low and others high)
  • Raynauds syndrome
  • Autoimmune disorders

and many, many more… This is by no means an exhaustive list.

Oxalate in spinach

Sources of Oxalates in the Diet

As we’ve already discovered, oxalates are naturally occurring compounds found in many plant-based foods. They are known to be toxic to humans (and some animals) when consumed at high levels, which can lead to episodes of not only kidney stones, but many other health problems.

While seed variety and growing conditions can create variation in the amount of oxalate in the same type of fruit or vegetable, leafy greens such as spinach and beet greens are among some of the richest sources of dietary oxalate.

One cup of raw spinach can provide around 350 milligrams of oxalate, and beet greens 380mg. Rhubarb is another significant source, providing about 370 milligrams per 1/2 cup. Nuts and legumes, such as almonds and peanuts, can contain moderate to high levels of oxalates. Almonds tend to be very high containing about 100mg per 1oz serving, and peanuts approximately 30mg per 1oz.

Sadly chocolate also contains high amounts of this poison, with dark 99% chocolate providing around 30mg per tiny 6g serve.

Other Sources

Oxalates can also be found in certain fruits, beverages, and grains such as mandarins, grapes, tea, and wheat. Wholegrains contain higher amounts than their white counterparts. Eg wholemeal flour is higher than white flour and brown rice higher than white. This is because most of the oxalate is contained in the hull of the grains.

There are many lists available online with the oxalate content of various foods, but be warned that some are more accurate than others, and they vary dramatically. There is a lot of misinformation and the testing of foods isn’t cut and dried. So a bit of caution, and ensuring you get your information from reliable sources is important. However it seems that even many of those sources you’d assume were reliable, often aren’t when it comes to oxalate levels in foods.

Sally Norton is one of the best sources of information I’ve found regarding oxalate as she’s studied this topic in depth for many years in an effort to resolve her own health challenges. I’ve linked to her book at the top and the bottom of this page for that reason.

It is important to note that not all plant-based foods contain oxalate, and eating a low oxalate diet once you know what foods are safe is do-able. Sally goes into great detail about how to do this in her book as well as explaining which foods to avoid and how much oxalate is safe.

By understanding the sources of oxalate, individuals can take steps to reduce their overall risk for oxalate-related health problems. Although it is virtually impossible to completely avoid oxalates in the diet, limiting intake of high-oxalate foods can be beneficial.

High Oxalate Foods You May Be Eating Daily

The following is a list of commonly eaten high oxalate foods:

  • Potato
  • Sweet Potatoes
  • Chocolate or Cacao
  • Raspberries
  • Blackberries
  • Figs
  • Kiwifruit
  • Mandarin
  • Rhubarb
  • Star fruit
  • Wholegrains such as wholewheat breads or brown rice
  • Buckwheat
  • Peanuts and some other legumes
  • Spinach
  • Swiss Chard or Silverbeet
  • Sorrel
  • Beet greens
  • Beetroot
  • Okra
  • Olives
  • Almonds
  • Cashews
  • Chia Seed
  • Black Pepper
  • Turmeric
  • Cinnamon
  • Black or Green Tea

This list is not exhaustive by any means, and there are many more plant foods that contain enough oxalate to be an issue. However these are some of the most commonly consumed high oxalate offenders, and a great place to start.

How to Reduce Oxalate Intake

Most people on a standard ‘healthy’ diet are eating enough oxalate containing foods that they will eventually feel the effects of oxalate toxicity in their bodies (albeit often unknowingly).

But if we have oxalate crystals that have accumulated in our body and then either stop eating oxalate or drop to a very low amount suddenly, this can cause unpleasant, and sometimes dangerous effects as our body begins to pull oxalate from the tissues to eliminate it.

This is commonly referred to as Oxalate dumping.

The safest bet is to reduce your oxalate consumption gradually over weeks or months, removing one food at a time, and replacing it with a low oxalate alternative. For example if you consume spinach or beet greens, switch to lower oxalate greens like broccoli, cabbage, or lettuce instead. Sally has many alternatives in her book.

Oxalate Creates Toxicity AND Deficiency

One more thing that I’ve not mentioned in this article is that oxalate binds to some minerals. It has an affinity for calcium in particular (hence most kidney stones being calcium oxalate), but also may bind magnesium or potassium, creating deficiencies in these minerals which are the spark for energy production in our mitochondria and essential for good health. Combine the deficiencies created with the toxicity and acidic nature of oxalate and you have a recipe for deteriorating health.

Toxicity combined with deficiency in the human body assures ill health and suffering.

✅ I recommend Sally Nortons book to learn more about oxalates.

2 thoughts on “Oxalate: The Poison In The Plants You Eat”

  1. Very good article!😊 But it should say that 150 mg is considered to be a somewhat safe number if you have good gut integrity, not 250. 250 is way too high.

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