If you are experiencing kidney stones, joint pain, bladder irritation, thyroid issues, or have fibromyalgia or autism, you may want to consider the impact of oxalates on your body, particularly if you eat a tonne of high oxalate foods such as spinach and beetroot.
What are oxalates?
Oxalates are naturally occurring molecules found in plants, and is also a waste product made by our bodies and yeasts.
Oxalates play a very important part in the defence of plants from being eaten by insects and other animals. As oxalates are toxic, they repel the animal. Unfortunately, they are also toxic to humans!
When we eat foods containing oxalates, the oxalates form salts by binding with calcium and to a lesser degree zinc and magnesium. When our bodies are not able to process these oxalate salts, they crystalise further in our organs, causing inflammation. This particularly affects our kidneys (in the form of kidney stones), our joints, our bladder and thyroid. This can cause irritation and inflammation in each of these organs.
Oxalates and the kidneys, joint pain and thyroid
Oxalate that is not bound to calcium travels as a waste product from the blood to the kidneys where it leaves the body in the urine. There are many different types of kidney stones, but eight out of 10 stones are calcium oxalate stones.
Oxalate that is not bound to calcium passes through the blood to kidneys to leave the body as urine. If there is too much oxalate and too little liquid in the urine (drinking at least 2 litres of water a day helps), the calcium-oxalate forms fragments which stick to each other to form kidney stones. Similarly the sharp oxalate crystals can lodge in our joints or bladder causing pain and irritability.
Whilst oxalate build up has been primarily associated with kidney stones, oxalate crystals have also been found in 79% of adults (1). Interestingly people with Hashimoto’s thyroiditis had less oxalate crystals in the thyroid, particularly in the parts that were inflamed.
This led the researchers to propose that the oxalates may have played a part in the development of Hashimoto’s auto-immunity. The oxalate crystals may have triggered an immune response to clear up the crystals which also damaged the surrounding tissue. This damage of our tissue by the immune system is known as auto-immunity and could play a part in the damage done to the thyroid, impairing it’s ability to produce thyroid hormones.
Root Causes of Oxalate Overload
Oxalate overload is the result of poor breakdown of oxalates in the body. This can be due to rare genetic disorders, yeast or mold in the body, or poor gut health.
Looking at poor gut health, this is typically an imbalance or an overgrowth of bacteria or yeast in the gut. This includes small intestinal bacterial overgrowth (SIBO), small intestinal fungal overgrowth (SIFO), or an imbalance of bacteria in the large intestine, Crohn’s disease, gastric surgery or a short bowel.
In particular, the bacteria Oxalobacter formigenes has an enzyme known as “oxalyl-CoA decarboxylase” that breaks down oxalate and so low levels of this bacteria are connected with poor clearance of oxalates and oxalate overload. Fortunately, the GI Map stool test now measures levels of this important bacteria.
Fungi, such as the yeast, Candida or mold, anywhere in the body can produce oxalates and lead to their buildup. We can test for oxalates, mold and Candida using the Organic Acid Test (see below). In many cases, addressing yeast or mold in the body can help clear up oxalate issues and the symptoms we have talked about.
Low Oxalate Diet
Most healthy people (without Candida or mold!) who consume a varied diet don’t need to worry about a ‘low oxalate diet’. They will consume on average about 250mg of oxalates without any issues. However, we need to remember that many healthy foods such as beetroot, sweat potato, spinach, cacao, and buckwheat are high in oxalates so it’s common for many people eating a lot of these foods, particularly people following a Paleo diet, to have issues. This is simply because they are consuming more oxalates than they can breakdown. This can happen in individuals that are ‘doing everything right’, and eating a health diet which just happens to be high in oxalates. A low oxalate diet could then be helpful.
Also, consuming less calcium (for example when avoiding dairy) can exacerbate oxalate issues as the calcium in dairy reduces our absorption of oxalates. If dietary calcium can not be increased, I recommend a Calcium Citrate and Magnesium supplement (such as the one from RNLabs) with each meal to help binding of oxalates in the gut.
When following a low oxalate diet, avoid these high oxalate food and drinks:
Drinks: Rice milk, dark beer, hot chocolate, chocolate milk, soy drinks
Nuts and Seeds: Nuts, nut butter, tahini, soy nuts, seeds
Starch: Wheat, buckwheat, brown rice
Fruit: Oranges, avocados, kiwi, raspberries, tomatoes, rhubarb
Root Vegetables: Beetroot, carrots, potatoes, sweat potatoes, parsnips
Other vegetables: Celery, eggplant, kale, leeks, capsicum, spinach, beans (baked, green, dried, kidney)
Other: Chocolate, parsley, soy products
For a comprehensive list of oxalate content of 170+ different foods, check out this list put together by Jill Harris and Fred Coe.
Whilst many recommend reducing your oxalate content by 10-15% a week, in order to avoid oxalate dumping (the release of stored oxalates from your tissue when oxalate levels circulating in the blood decreases). A more practical approach is to start by reducing the oxalates in your diet to less than 100mg a day. Let the body adjust and settle down, and then decrease further to less than 50mg of oxalates. When you feel better you can let higher oxalate foods creep back in..
For people who have Candida or mold in their system or bacterial overgrowth in their gut, the focus should be on fixing these underlying causes, rather than a low oxalate diet.
Conjugated Bile Acids
Conjugated bile acids can also help to clear out oxalates from the gut by preventing their reabsorption. An ox bile supplement and also taurine to supplement bile flow may be something else to include when looking to reduce oxalate overload.
Lab Testing for Oxalates
If you suspect you have an oxalate overload, testing oxalate in the urine is recommended. In Australia, Nutripath offer urinary oxalate testing. However, for a more comprehensive view, I recommend the Great Plains Organic Acid test.
The organic acid test, not any tests oxalic acid levels, but also glyceric and glycolic acids. When glyceric or glycolic acids are elevated it indicates that oxalates may be elevated due to genetics (though there can be other causes such as Candida). Vitamin B6 can be helpful in this instance, although it’s useful to keep on an eye on your homocysteine levels as large does (>50mg) can potentially lower homocysteine too far.
The organic acid test is also an excellent testing choice as it also provides markers that indicate Candida or Aspergillus and Fusarium molds in the body – both of which can cause elevated oxalates.
Oxalates are toxic compounds food in many ‘healthy’ plant foods. Candida and mold in the gut can also lead to their build up. When oxalates accumulate in the body and form crystals they cause inflammation, pain, irritation, and even auto-immunity.
Oxalates are easy to test using urine lab testing. When elevated, the root cause such as poor gut health should be addressed first. There are several supplements that may be helpful including calcium citrate, ox bile, Vitamin B6 and probiotics.
If you are consuming a lot of oxalates, a trial of a low oxalate diet is also an option.
As a gut health expert and Functional Medicine practitioner, I’m available to guide you on a personalized journey to identify and address the root causes of your oxalate issues. Together, we’ll develop a tailored nutrition, supplement, and lifestyle plan to restore balance and improve your overall health. Don’t hesitate to reach out and embark on this transformative path to better understand and conquer your oxalate issues, while unlocking your body’s full potential.