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Oxalates: Plant Toxins on Your Plate

Oxalates: Plant Toxins on Your Plate

What in the World are Oxalates?

Oxalates are plant toxins that are present in almost all plant foods to some degree. Why are they there you ask? Oxalates are a basic defense mechanism plants use to protect themselves from danger, as in predators. You know, the creatures that want to eat them? Oxalates are anti-nutrients. These molecules inhibit the absorption of minerals like calcium. They are disadvantageous in most people. But in some people, they can become a real problem.

There is oxalate content in most plant-based foods in varying degrees. Oxalates are high in many vegetables, particularly spinach, beets, chard, and rhubarb. They are also very high in nuts, which are used frequently on grain-free diets like the Paleo Diet, the Specific Carbohydrate Diet and GAPS as they tend to replace SAD (Standard American Diet) baked goods with baked goods made of high oxalate flours like almond flour. Some of the alternative gluten free grains that are popular these days on diets such as the Body Ecology Diet are quite high in oxalates as well. Milk substitutes on the GF/CF diet can be another source of oxalates. Juicing can provide potentially high doses.

Oxalate is a molecule that forms inflammatory little crystals that can accumulate in tissues and cause pain. They can interfere with cellular chemistry and perpetuate a cycle of mitochondrial dysfunction. They interfere with mineral metabolism and intracellular trafficking. They cause oxidative stress and damage and prevent healing.

Signs and Symptoms of Oxalate Problems

Urinary pain and urgency. Cloudy urine or crystals in urine. Kidney stones. Grainy or sandy stools. Gut problems and problems digesting fat. Bloated belly. Constipation or IBS. Insomnia and night-waking. Fatigue. Joint pain and arthritis. Eye pain. Brain-fog. Mood issues. Skin issues. Allergies. COPD. Thyroid problems. Low energy. Low tone. Poor motor skills. These are some of the symptoms people may experience due to oxalates.

Oxalates are associated with autism, fibromyalgia, chronic fatigue, cystic fibrosis, IBD, intestinal resections, gastric bypass, chronic pancreatitis, interstitial cystitis, vulvodynia, thyroid disease, chronic systemic candida, mitochondrial dysfunction and more.

How Can These Healthy Foods be so Problematic?

You may be asking yourself at this point why people would have so much difficulty with such healthy foods. It doesn’t make logical sense, does it? Aside from serious overconsumption, there are several reasons and many of them relate to our modern food, lifestyle and medicine.

Hyperoxaluria is the excessive urinary excretion of oxalate. Some people do have a genetic form of hyperoxaluria, called primary hyperoxaluria, and they produce oxalates endogenously (their body produces them) due to mutations in the genes that code for specific enzymes. However, our modernized, processed and often genetically engineered food, pharmaceuticals and stressful lifestyles contribute to oxalate problems as well. Where leaky gut is an issue, or bowel inflammation is present, higher percentages of oxalate from the diet will be absorbed. This is called enteric hyperoxaluria. Further, when gut bacteria is destroyed by antibiotics and such, we can no longer put it to use degrading the oxalates from our food. There is another group of people perhaps much more common than is recognized that I suspect are producing oxalates endogenously because of temporary errors in biochemistry and metabolism for various reasons, and therefore have a lower tolerance for it in foods. Vitamin and mineral deficiencies may be responsible because they are important cofactors in specific reactions; Vitamins B1 and B6 are perhaps best known for this. Candida has also been implicated although it appears to be more of a correlation than a causation and this is at this point a chicken or the egg debate.

The Research

Susan Owens is Head of the Autism Oxalate Project at the Autism Research Institute. She studies the literature on oxalate, talks to the scientists in the field, and interacts regularly with those on the Low Oxalate Diet. You can find her at Trying Low Oxalates Yahoo group, her listserve where she is both teacher and student, sharing information as an expert in the field, but listening intently to low oxalate dieters at the same time and gleaning insight from them. Her group is the most extensive source of information on oxalates you will find.

Owens shares a wealth information at her forum, much of it derived from a tremendous database of biochemical tests she has collected from children and adults on the diet. Susan studies these biochemical tests and makes some very interesting connections. One fascinating realization that Susan has made is that oxalate levels in the body often increase dramatically during or after prescription antifungal and antibiotic treatment. This is aligned with what I have seen. Whether natural antibiotics or antifungals create the same scenario is not understood at this time. Owens also holds that it has not been studied or proven that yeast causes excess oxalate in the body, but that oxalate makes you more susceptible to yeast overgrowth. I admit that I was originally skeptical of this theory, but it also seems to be more aligned with what I have seen over time.

Interesting Tidbits

This recent study in the European Journal of Paediatric Neurology is the first of its kind and it found that oxalates may be involved in the pathogenesis of ASD in children. I hope more research is done in this area soon!

This recent article about a doctor that went on a low oxalate diet for her fibromyalgia and her symptoms disappeared inspired a low oxalate movement in the fibromyalgia world. Did you know that eating 11 lb of rhubarb (I assume she means in one sitting) would kill you?

High doses of Vitamin C are contraindicated for people with oxalate problems, as Vitamin C can convert to oxalate. It can take up to two weeks for that conversion to occur so one may not associate the symptoms with the addition of Vitamin C.

Oxalates are now being used in chemotherapy. Oxaliplatin, like other chemotherapeutic agents, is cytotoxic, meaning that it is toxic to cells. But it also releases large amounts of oxalate into the blood, causing additional symptoms.

Going on a Lower Oxalate Diet

Oxalate gets stored in tissues because our bodies needs to get it out of circulation. If you do see the need to lower your dietary oxalate, it is very important to know that your body will release or “dump” these stores from the tissues into the bloodstream when you decrease your intake of oxalates, and as the oxalate moves from an area of higher concentration to an area of lower concentration you may experience severe symptoms. It is not a good idea to do this quickly. If you are not very careful with the transition, you will likely feel worse before you feel better. Talk to your doctor before making any dietary changes, and please do not attempt to do this diet without support. The Trying Low Oxalates Yahoo Group is a great place to go for help.

Final Thoughts

In my opinion, in modern times with food allergies and intolerances and special diets, our nutritional regime can get out of balance quickly. Oxalates are an important consideration for everyone, particularly those of us with autism, ADHD, allergies, autoimmune and digestive disorders. When our special diets are implemented without consideration for oxalates, these troublesome molecules can mask the benefits of the diet you are attempting to implement and cause new and undesirable symptoms. I like to model my diet after a traditional diet because these diets stand the test of time. If we are eating spinach salads everyday, we have to wonder whether spinach would be available to traditional peoples year round? I think these kind of questions are important questions that all of us need to ask ourselves, but it is even more important to ask when we are on an alternative diet and trying to replicate the Standard American Diet with substitutes for grains, flours and milks and such. Some of these substitutes do not stand the test of time. Paleo and other grain free diets are great, and yes, they can be implemented as a traditional diet, but there is nothing traditional about eating nut flour baked goods three times a day! I can’t imagine Paleolithic man spending all day cracking nuts open, can you? So keep oxalates on your radar while implementing your healing diet. This just may be another layer of the onion for you!

For more information:

Trying Low Oxalates Yahoo Group – the most current research and Susan Owens herself can be found here.

Low Oxalate Diet – a great source of consolidated information but the most current information and food list will be at the Yahoo group above.

The Role of Oxalates in Autism and Chronic Disorders – an article written by William Shaw of Great Plains and appearing in Wise Traditions, the journal of the Weston A. Price Foundation. Please note that Shaw’s theories on the connection between candida and oxalates are not consistent with the literature according to Owens, and yeast treatment appears to contribute to the oxalate problem in many people rather than alleviate it according to the data she has seen so far.

Come join my group on Facebook, where we are always discussing these issues! 

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See related article:

The Oxalate & Salicylate Connection


This post was featured in Real Food Forager’s Sunday Snippets and The Polivka Family’s Family Table Tuesday.



  1. Wow! Lots of great reading and things to think about.

    Thank you for sharing this at Motivation Monday!

  2. April says:

    Thanks for sharing about this, I have trouble absorbing iron, and found out that some of the foods like spinach actually make your body unable to absorb the iron in the food, and that one should be careful to not eat too much of that kind of food due to the oxalates. Thanks for more info, very interesting. 🙂

  3. Jenny says:

    This is frustrating though, because no tips are being offered, or at least not clearly. It would be nice to see some basic steps/bullet points for reducing oxolates right here instead of having to search through other links. How can I turn this information into a part {or not a part} of tonight’s dinner?
    Thank you 🙂

    • Dawn Tasher says:

      Hi Jenny,

      I understand your frustration. Because reducing oxalates can be a very uncomfortable process and it can be dangerous if done too quickly, I tried to make it very clear in the article that it should not be done hastily or without support. I think it is a VERY big piece of the puzzle for so many, but many people do not pursue it because of the education it requires. I did list some of the highest oxalate foods like the spinach family and nuts, but it would not be wise to just start eliminating oxalates without really knowing what you are doing.

  4. […] in case you missed my most recent posts: Oxalates: Plant Toxins on Your Plate – oxalates may play a role in autism and other health problems. Too Much Blame on the […]

  5. […] Oxalates: Plant Toxins on Your Plate from Peeling back the Onion Layers. Comprehensive post about oxalates. […]

  6. Happy New Year wishes and thank you for sharing at the hop. I hope you will stop by again soon. I posted the new giveaway! xo

  7. Very interesting. I hear more and more concern about oxalates but I think that we will worry ourselves into starvation if we try and cut out everything including healthy food.
    I used to suffer from a lot of the health problems that you listed and did a lot of research into how to recover my health and finally opted for vegan. I didn’t feel quite as good as I wanted so I went on a 6 month raw food diet where I ate mainly fruit and salad veg with a small amount of nuts and seeds. I totally recovered my health despite eating spinach every day. Now I eat cooked food but try and eat everything unprocessed and as natural as possible and that’s the best I can do with what the food that I have access to. I think there are many traditional diets and it doesn’t really matter which one you follow as long as the food is unprocessed and not tampered with. Everything is tampered with these days so it’s very difficult to do this so we just have to do the best we can with what we’ve got.
    I have been drinking daily green smoothies for 3 years (apart from 3 months of pregnancy) and feel so much better on these but I understand not everyone will be able to tolerate such high levels of greens. I agree with you that we should also try and eat seasonally but I think our natural environment (and most healthy environment) would be one that fruit and veg could grow all year round with plenty of sunshine! (Not freezing cold Scotland where I live!)

    • Dawn Tasher says:

      I know what you mean about worrying ourselves into starvation! I definitely would not worry about it if it is not an issue for you, it is just something to keep on your radar. We do store oxalates in our bodies and at some point we could develop a problem. We may have to be predisposed to a problem like this, but I can’t tell you how many people have said they did years of green smoothies or juicing or spinach salads or almond flour breads and then the symptoms started. As far as traditional diets, I am Italian and I think I do best when I stick to a more Mediterranean style diet; perhaps these are the foods my genes are used to. I know that genetics play a role here…for example, I have read that people of Asian descent have a larger pancreas and do well with a lot of carbs…I might not fare as well on that diet. So sometimes it takes troubleshooting within the context of a traditional diet. You might be surprised by just how sensitive to various foods some of the people I work with are!

      • Yes that makes a lot of sense. It’s interesting about traditional foods. It’s so hard to define what’s traditional anymore as we move around so much. I do very well on potatoes and oats which are traditional foods in the UK but I know a lot of people can’t tolerate them. However I do have some Indian ancestors and I adore curry and usually tolerate that quite well too. Thank you!

  8. […] 2. Oxalates: Plant Toxins on Your Plate @ Peeling Back the Onion Layers […]

  9. This is worrying, my husband drinks beet juice all the time:-(

    • Dawn Tasher says:

      I would not worry too much if he is not drinking tons of it or consuming a very high oxalate diet in general…beet juice is very healthy stuff for most people. Just keep it on your radar!

  10. Very interesting! Something that is new to me! Glad we connected and glad I can learn from you!!

    Thanks for linking up at our Gluten Free Fridays party! I have tweeted and pinned your entry to our Gluten Free Fridays board on Pinterest! 🙂

    Be sure to check out the winning entry this week for our Better Batter Giveaway! The winner will be announced Thursday evening!

    See you there!

    Cindy from

    • Dawn Tasher says:

      Thank you so much, Cindy! Thank you for hosting and for all of your support!!! I will definitely be there! 🙂

  11. Melanie says:

    Thanks so much for sharing at Wednesday’s Adorned From Above Blog Hop.
    Debi and Charly @ Adorned From Above
    Melanie @ Keep It Simple & Fun

  12. […] Oxalates: Plant Toxins on Your Plate – oxalates may play a role in autism and other health problems. […]

  13. […] Oxalates: Plant Toxins on Your Plate from Peeling Back the Onion Layers […]

  14. Vincent Alexander says:

    I’d like to see a chart. A list of fruits/veg with oxalate content to use as a conscious guide when juicing and consuming a lot of raw fruits and veg just to avoid over doing it on the high content varieties. Can Swiss chard be blanched to reduce oxalate content?

    • Dawn Tasher says:

      I don’t list charts because I really don’t want people to take on this diet irresponsibly. You really need to be entrenched in the science and working with a doctor to do this safely. For the average person just watching their oxalates, there are lists online (although they are less detailed and less accurate than the Trying Low Oxalates forum). Thanks for stopping by!

  15. I love this quote: ” I like to model my diet after a traditional diet because these diets stand the test of time. If we are eating spinach salads everyday, we have to wonder whether spinach would be available to traditional peoples year round?”

    Very symbolic, and very true. Thanks for a great article, Dawn.

    • Dawn Tasher says:

      Thanks so much, Eileen! I read your work a lot and really respect your opinion so that means a lot to me! 🙂

  16. Kaye says:

    I have just found your website. Amazing. I have suffered over many years with some of the problems you have listed the main one being Fibromyalgia, which has been getting worse over many years. In 2014 my cousin found the article the English Doctor wrote on Oxalates. I had already begun to realise that some foods were affecting me and was having a little success in cutting them out. Have now taken a few more things out, red beet, silverbeet, wholemeal flour plus others and have made even more progress. I am now getting a lot more energy back – still a way to go but have to remember it took a long time to get there in the first place. I wonder if this may have been a problem from childhood. I had not thought of putting into Google “allergy to Oxalates”
    My GP always asks if I have come up with any more ideas s she says she is getting quite a few patients with the Fibromyalgia symptoms. Thank you.

  17. Lhersh says:

    Hi there, quick question…does cooking these vegetables before consumption make them lower in Oxalates? Curious because cooking/heating reduces so many other attributes.

    • Dawn Tasher says:

      Hi There!

      Not really. Boiling and dumping the water does often help, because oxalates end up in the cooking water. We don’t love to boil our food or lose the nutrients by dumping the boiling water so we tend to steam and stick to lower oxalate.

  18. […] has been several years since I wrote my original article on oxalates.  That article was a brief overview, barely scratching the surface of a topic that I have had […]

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