How Plants Can Kill (Part-1)- Oxalates

July 30, 2020

Plants often contain toxins acquired from fertilizer and pesticides and several naturally occurring chemicals. Some of these chemicals are known as secondary metabolites or anti-nutritional factors and are very active compounds. Anti-nutritional factors are known to interfere with metabolic processes (for e.g.,growth) and availability of nutrients is also negatively influenced. Oxalate is one such potent ‘anti-nutrient’ present in many plant foods.

Oxalic acid or Oxalates are plant derived toxic substances, which cannot be either seen, smelled or tasted. Oxalic acid is a naturally occurring tiny molecule that is also a corrosive acid.

When minerals get attached to oxalic acid, it is called Oxalate (E.g. sodium oxalate, potassium oxalate, magnesium oxalate, calcium oxalate). It is obtained mainly from plant based foods and occurs in many shapes and sizes.

Foods high in oxalates-

Beans, Grains, Bran, Sesame, Peanuts, Almonds , Starfruit, Spinach, Beets, Potatoes, Chocolate, Figs, Kiwi, Blackberries, Black pepper, Cumin, Turmeric.

Foods low in oxalates-

Meats, Dairy products, Eggs, Fats and Oils, Avocado, Cabbage, Cauliflower, Cilantro, Cucumber, Garlic, Lettuce, Mushrooms, Green peas.

These are natural defense compounds that plants produce so that animals avoid eating the. The list of high oxalate foods is quite long and you can get it from a whole lot of plant based foods. 

It can also be produced as a metabolic byproduct in your body with no known function. Higher amounts are made when you are deficient in B6, or if you consume high doses of vitamin C though the exogenous (ones coming from outside) oxalates are far more dangerous than the ones that your body makes. 

Oxalate dangers 

Your body cannot handle oxalate and hence always tries to excrete it, sometimes the excretion gets impaired either due to high volume of oxalates coming in from the diet or due to dysfunctional excretion pathways. Eitherways, this dangerous plant toxin must not be ignored as here’s a whole list of problems related to oxalate toxicity.

  • Nutrient deficiency

Oxalates steal minerals from your diet as well as your body and make them useless (it is an “anti-nutrient”). Soluble forms of oxalate (sodium oxalate and potassium oxalate) can be picked up by other minerals like magnesium, calcium, iron, zinc, copper, etc. This locks up the minerals. It may also bind with toxic metals such as lead, mercury, aluminum, or cadmium.

Mineral deficiency causes growth, reproductive, and other problems. It may also deplete the B-vitamins- B6 and biotin. Oxalates use up vitamin B6, possibly initiating a vicious cycle. B6 deficiency increases internal production of oxalate, increases oxalate load, further depleting B6, and so on. Biotin metabolism is also altered and the levels of Biotin in your body can decrease.

This is one reason why a lot of vegans and whole food plant based diet followers end up with severe deficiencies.

  • Gastrointestinal damage

 It is corrosive to the lining of the digestive system, and may cause leaky gut or other GI diseases. Some oxalate crystals have a needle shape known to perforate mucus membrane cells.

  • Kidney dysfunction

The crystals can challenge the kidneys and can overwhelm their capacity to remove them from the blood. A delayed effect of oxalate ingestion is kidney damage, which can lead to renal

failure due to deposition of oxalate crystals. Kidney stones usually contain these crystals.

  • Chronic pain 

Oxalate crystals implant themselves in areas where they prevent other material from passing through and this is how it can lead to a great amount of pain in your body.

  • Neurotoxin

Oxalates are considered to be brain toxins. They can damage brain nerves. While the signs of oxalate neurotoxicity covers a spectrum of symptoms including hiccups, convulsions, and even death.

  • Antioxidant depletion

Oxalate crystals are capable of depleting the level of antioxidants in your body, especially those of one of the important antioxidants- Glutathione. Low levels of glutathione can generate increasing toxic stress causing early cell death. It is particularly very important in the liver for the detoxification of chemicals and also for preserving brain health.

  • Autoimmune diseases

Oxalates can cause cell communication problems to carry out their functions and further confuse and stress the immune system, thereby creating auto-immune symptoms.

  • Connective tissue damage

Oxalates destroy the key building block of the connective tissue (hyaluronic acid). This makes it much harder to fully recover from injury, even surgery can weaken or destabilize joints, bones, skin (skin may be thin or easily damaged) and can make you injury prone. Damage to the connective tissue can contribute to aging and can make you feel old prematurely.

  • Modern lifestyles

Modern lifestyles may be increasing the number of people affected by dietary oxalate, by increasing exposure and lowering our tolerance. It is easier than ever to eat a high oxalate diet. High-oxalate foods are now more accessible year-round and very popular. Ironically, the health-conscious may have a greater affinity for some high-oxalate foods such spinach and almonds which are promoted as healthy.

  • Increased use of medications

 The oxalates we munch on may be more readily absorbed and less efficiently excreted from the body due to our reliance on medications, including over-the-counter pain and cold medications and popular prescription drugs. These drugs can harm the gut flora and function, and reduce the kidneys’ ability to remove them from the body.

  • Exposures to toxins

 Adequate oxalate excretion can also be impaired by other toxic exposures, such as indoor air pollution, which can impair kidney function.

  • Resection surgery

  Gastro-intestinal resection surgeries dramatically increase susceptibility to food oxalates.

The potential for harm from a high oxalate diet can be magnified by other factors besides the health and function of the gastro-intestinal (GI) tract and kidneys.

  • Diet low in Fibre and Calcium

 The mix of foods within your meals affects how much oxalate is absorbed and how much your body has had to handle over your lifetime. For example, meals rich in calcium and fiber can lower the amount of oxalate absorbed from foods, while diets low in fiber and calcium may increase the amount of oxalate you absorb.

  • Fetal exposure problems

 Fetal exposure to oxalate and other toxins may set the stage for oxalate trouble, perhaps including autism and other brain function issues, such as learning and behavior problems.

These problems, however, do not always cause obvious symptoms. Onset may include a generalized malaise, poor concentration, some sort of “-itis” (gastroenteritis, tendonitis), joint stiffness, swelling, muscle pain or weakness.

There are undoubtedly many other factors that are yet to be discovered and documented. 

Lethal Oxalate dose

The lethal dose for an adult is about 15 to 30 g, but the lowest reported fatal dose is only 5 g (or about 70 mg/kg) (2).

Detection of Oxalate

Long-standing technical difficulties have made measuring oxalate in blood and urine unreliable, leading to ignorance of the problem of oxalates entirely. Since the 1990s, modern technical advances have made it possible to accurately measure oxalate in urine, but the ability to detect oxalates still has not changed the medical habit of ignoring oxalate in the body, even for patients with oxalate kidney stones.

On the rare occasions when urinary oxalate is measured, it is analyzed badly—most often due to inadequate handling and workup of the urine sample prior to actual measurement. Very few medical offices are equipped with the knowledge, training, and skill to successfully conduct this specialized testing.

Practically speaking, the safest, most affordable and most reliable test is correctly trying the low-oxalate diet with a good understanding of how your body can react to it.

Low oxalate diet- a way forward

Non-toxic nutrition is the key to feeling better and having a better functioning body and brain. The most straightforward way to relieve the pain of oxalate poisoning is to: stop eating foods high in oxalates (gradually), and choose nutritious, low-oxalate options. 

You can replace the high oxalate foods with cucumbers, radish, lemon, banana, flaxseeds, raw pumpkin seeds, coconut milk or coconuts, oats or oat milk, etc.

You should also improve your calcium and fiber intake from your diet as they can help in excreting the oxalate load. However, do not overdo it.

So, oxalate rarely gets the blame, even in part, for the problems they are capable of causing. This hidden but nasty toxin should not be ignored. If you or your loved ones are facing any of the oxalate-related dangers and have tried treatments that have not worked, you can certainly reach out to iThrive for help.


Ria Jain
Functional Nutritionist

Ria has a Master’s in Nutrition and Dietetics and is in a permanent research mode and keeps the rest of us at iThrive (Previously ThriveFNC) updated with her latest findings in the field of Nutrition. Her articles on iThrive's blog are an expression of her research findings. We really don’t know what we’d do without her support and her focus.

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