What are Oxalates? - Jill Dumas Nutritional Therapy Skip to main content

What are Oxalates?

Oxalates (oxalic acid) are anti-nutrients found in abundance in many plant foods, mainly vegetables and fruits. Although they help protect the plant from animals, insects and fungi, they also keep your body from absorbing essential nutrients in food. When oxalates bind to calcium in your blood, tiny, sharp crystals oxalic acid form and can be deposited anywhere in the body, and can cause muscle aches and pain.

When oxalates accumulate in the body, either from a high oxalate diet or your body having difficulty removing them, they can cause many health problems. Tiny oxalic acid crystals in the muscle and connective tissues may cause muscle aches and pain. High oxalates can also lead to kidney stones, gout, oxidative damage, glutathione depletion and increased inflammation. Individuals with chronic illnesses, such as chronic fatigue syndrome or gut issues will often have high oxalates.

Oxalates also bind to minerals such as calcium, iron or magnesium, making them no longer available for absorption. This is why oxalates are called ‘anti-nutrients’ – they can cause a deficiency even when you are eating plenty of mineral rich foods.

Who is at risk of harm from oxalates?

In healthy individuals with a robust microbiome, oxalates in the diet do not cause any problem as normally, there is little oxalate that is absorbed from the diet. However, the level of absorption has to do with the condition of the gut.

  • Those with digestive issues – When there is poor digestion, inflammation and/or leaky gut, excess oxalates can be absorbed from the gastrointestinal tract and become a problem for other cells in the body. Likewise, changes in the composition and number of microbes in the gut (dysbiosis) may also increase the impact of oxalates. Don’t forget that high stress and poor diet can also damage bacteria in the gut.
  • Antibiotic usage – Those with recent or heavy antibiotic use may be at greater risk from dietary oxalates. Antibiotics and other medications damage and kill gut bacteria that degrade oxalates and help maintain low oxalate levels, including oxalobacter formigenes, lactobacillus acidophilus and bifidus. Oxalobacter in particular cannot survive without eating oxalates. Studies have shown that those with oxalate-related issues generally lack oxalobacter in their stool.
  • Kidney issues and kidney stones – 75-90% of kidney stones are oxalates. Individuals with kidney stones or any kidney issues should consider a low oxalate diet.
  • Deficiencies – Vitamin B6, magnesium or thiamine (vitamin B1) may contribute to a decreased ability for your body to excrete oxalates.

High Oxalate Symptoms

  • Fibromyalgia
  • burning eyes, ears, mouth and throat
  • nausea
  • diarrhoea
  • headache
  • kidney stones
  • muscle twitching, muscle pains
  • weak or irregular heartbeat
  • irritable bowel syndrome (IBS) or symptoms of
  • difficulty concentrating or trouble focusing
  • mineral deficiencies (oxalates bind to calcium, zinc and magnesium)
  • osteoporosis or brittle bones

Sources of Oxalates

1. Oxalates from food

These foods have the highest oxalate amounts.

  • Raw dark green leafy vegetables such as spinach, kale, chard, boy chow, cauliflower, broccoli, parsley
  • beetroot
  • potatoes
  • radishes
  • black pepper
  • buckwheat
  • chocolate
  • nuts, including almonds, cashews, peanuts
  • berries
  • sorrel
  • beans, especially black, navy and pinto
  • soy products

2. Oxalates from fungi or yeast

Oxalates can suppress the immune system, making one more susceptible to yeast overgrowth. Fungi such as Aspergillus (a type of mould) and Candida (a type of yeast) can produce oxalates. Aspergillus can combine with heavy metals in the GI tract. Therefore, along with a low oxalate diet, it is imperative to address yeast, mould and heavy metals to reduce the overall oxalate load. Check out Mould Toxicity and Heavy Metal Toxicity for more info. Addressing one or both of these could be the answer to reducing your oxalate load.

3. Oxalates produced in the body

In addition to food sources, the liver is able to make oxalates. Ensuring adequate vitamin B6 status can minimise oxalate production. An enzyme that depends on sufficient vitamin B6 is required to shift the reaction away from oxalate production and to process oxalates for removal from the body. (1) Individuals with low vitamin B6 won’t have the ability to clear oxalates from the body properly.

Solutions for high oxalate symptoms

1. Low oxalate diet

A normal diet contains anywhere between 75-200mg of oxalates per day. A low oxalate diet contains less than 50mg/day. There are plenty of low oxalate diet resources on the internet to help you get started.

Oxalates bind to calcium. Individuals eating a large amount of raw vegetables and little calcium (such as the raw food diet) should consider calcium supplementation to help reduce oxalates.

Be weary of green smoothies with lots of raw green leafy veg (I’m looking at you, spinach & kale!). If you want to add these greens to your salads or smoothies, steam them first. Adding magnesium and calcium (see below) to your smoothie can lower its oxalic acid.

2. Supplementation

  • Take calcium citrate and magnesium with each meal so they can bind to and neutralise oxalates. This means you won’t absorb as much of it.
  • Vitamin B6 stimulates an enzyme to form glycine instead of oxalic acid.
  • Probiotics – spore based probiotic that improve gut flora and commensal bacteria such as Megasporebiotic.

3. Address the root cause of high oxalates.

This could be infections, mould illness, heavy metal toxicity or fungal overgrowth. It could also genetic (caused by liver enzyme deficiencies).

Doing a Great Plains Laboratory organic acids test (OAT) from is a great way of assessing current oxalate status, including fungal, bacteria and mould markers which can help determine why the high oxalates are present.

4. Open drainage pathways

Oxalates are removed from the body through poo and urine. You should be doing at least one (ideally 2-3) well-formed bowel movements each day, along with healthy urine output.

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