Written By: Kelley Herring
“Don’t forget to eat lots of leafy greens to get your folate!”, the doctor said as she left the patient’s room…
The patient in this case was my friend’s daughter. She is a lovely girl on the autism spectrum. She has already experienced significant progress by switching from a Standard American Diet (SAD) to a whole-foods Paleo diet. Now, her mom wants to know what else she can do to improve her health and abilities through additional dietary changes.
And while “Eat more greens” might seem like a helpful (or at the very least harmless) piece of advice… for many people, eating more greens could be a dangerous course of action that increases pain and suffering. This is especially true for those with autism.
And the reason is oxalates.
What Are Oxalates?
Oxalates are hard, crystalline compounds. They are found in most of the plants we eat. They are also produced in the body, as certain substances are broken down.
For most individuals, oxalates are metabolized by healthy gut bacteria or eliminated as waste products.
However, for some people, the body may absorb oxalates from the gut into the bloodstream… and then have difficulty eliminating these compounds. What’s worse, these jagged, sharp crystals can become lodged in healthy tissues causing a wide range of health problems.
Symptoms & Diseases Related to Oxalates
- Kidney stones
- Joint pain and inflammation (similar to fibromyalgia or arthritis)
- Insomnia, anxiety and depression
- Gastrointestinal problems (IBS & IBD)
- Thyroid dysfunction
- Autoimmune illness
- Child developmental disorders, including autism
- Mineral deficiencies (calcium and magnesium)
- Chronic inflammation
- Gut dysbiosis
- Mitochondrial dysfunction
- Vulvodynia (female genital pain or irritation)
- Chronic candida (yeast infections)
Excess oxalates can also cause oxidative damage and depletion of glutathione (your body’s master antioxidant and detoxifier). This can impair your ability to repair DNA and detoxify, resulting in cellular mutation, heavy metal accumulation and more.
And for those diagnosed with autism, impaired detoxification, mitochondrial dysfunction, gut dysbiosis and heavy metal accumulation are notoriously problematic.
So, why would we want to encourage people with autism to consume foods that could actually worsen their condition and long-term prognosis?
Unfortunately, most diets that are recommended for autism – including the Gluten-Free/Casein-Free (GFCF) diet, the Paleo Diet, the GAPS diet and the SCD diet – fail to take oxalates into account.
Let’s take a look at the research on how oxalates impact autism…
High Levels of Oxalates Present in Autism
A recent study published in the European Journal of Paediatric Neurology investigated the role of oxalates in autism. Researchers discovered that children with autism had 2.5-times greater oxalate levels in the urine and 3-times greater levels in the blood.[xii]
And because urine testing is the standard method for evaluating oxalate load, those with high blood levels (but lower levels in the urine) are often misdiagnosed.
This study also specifically excluded children on a special diet, those with a history of seizures or antibiotic use, and those with gastrointestinal disease or kidney stones.
This is very important to note, because a significant portion of the autistic population fall into these categories[xiii][xiv][xv] and all of these factors are known to be related to or caused by high oxalate levels (hyperoxaluria). This indicates that the levels of oxalates in these sub-populations of autistic children were likely even higher!
“Ordinarily, not much oxalate is absorbed from the diet, but the level of absorption has to do with the condition of the gut. There is a lot of medical literature showing that when the gut is inflamed, when there is poor fat digestion, when there is a leaky gut, or when there is prolonged diarrhea or constipation, excess oxalate from foods can be absorbed from the GI tract and become a risk to other cells in the body. Since these gastrointestinal conditions are found frequently in autism, it seems reasonable to see if lowering the dietary supply of oxalates could be beneficial.”[xvi]
Oxalates & Detoxification
Another way that oxalates impact autism is via their impact on sulfation pathways.
Sulfation is an important part of detoxification. In fact, sulfur-containing molecules are critical to the function of glutathione pathway – which helps detoxify and remove harmful substances (including heavy metals) from the body.
People within the autism spectrum have a tendency to excrete sulfur. And when sulfate is low, oxalates bind to cells more easily, causing dysfunction. Oxalates also lead to poor sulfation, creating a vicious cycle.[xvii][xviii]
High Oxalate Foods (50-300 mg/serving)
Now that you’ve learned how oxalates can impact autism, let’s take a look at the highest-oxalate foods to avoid:
- Star fruit (carambola)
- Sesame seeds
- Swiss chard
- Rice bran
- Bran flakes
- Beans (most)
- Miso soup
- Chia seeds
- Sweet potatoes
- Dark chocolate
- Berries (raspberries, blackberries)
- Nut butters
- Nut milks
With this list in mind, it is important to note that 80-90% of urinary oxalate is produced inside the body (as opposed to being consumed). The amount produced can depend on many factors, including vitamin deficiencies (vitamin A, B6, B1), genetic variations and biochemical conversions from other foods (including ascorbic acid, glycine, fructose and xylitol).[xxi]
The amount of oxalate absorbed from the foods we consume ranges between 5-15%. This, of course, depends on your consumption of foods that are naturally high in oxalates (like “leafy greens”). It can also depend on consumption of calcium, magnesium and fiber, all of which bind to oxalates and help remove them from the body.[xxii]
We are All Biologically Unique!
One of the greatest lessons we have learned about health and nutrition over the last several decades is that each one of us is biologically and genetically unique. Rigorous scientific research has proven that for all of our human similarities – after all, we have the same basic physiology and anatomy – our individual nutritional and dietary needs are quite unique!
So, do not blindly accept that all “healthy foods” are going to be good for you. They might not be. And if you don’t feel well, consider “subtracting before you add”. That means, it’s probably best to eliminate foods from your diet – starting with “plant-based” foods first and gauge how you feel.
In my next article, we will continue this discussion of oxalates (particularly their effect on those with autism) and specifically how to improve our health by reducing oxalates in the diet.
Read more Health and Wellness articles from Kelley Herring on our Discover Blog.
Love comfort foods, but not the carbs? Check out Kelley’s FREE new book – Carb Lover’s Keto – with 100 recipes for all of your favorite comfort foods. From Chicken Parmigiana and Coconut Shrimp to Buffalo Wings and Pizza. Discover how you can indulge – 100% guilt free!
[i] Baggish MS, Sze EH, Johnson R. Urinary oxalate excretion and its role in vulvar pain syndrome. Am J Obstet Gynecol. 1997 Sep;177(3):507-11. doi: 10.1016/s0002-9378(97)70137-6. PMID: 9322615.
[ii] Ogawa, Y., Miyazato, T. & Hatano, T. Oxalate and Urinary Stones. World J. Surg. 24, 1154–1159 (2000). https://doi.org/10.1007/s002680010193
[iii] Mitchell T, Kumar P, Reddy T, Wood KD, Knight J, Assimos DG, Holmes RP. Dietary oxalate and kidney stone formation. Am J Physiol Renal Physiol. 2019 Mar 1;316(3):F409-F413. doi: 10.1152/ajprenal.00373.2018. Epub 2018 Dec 19. PMID: 30566003; PMCID: PMC6459305.
[iv] Konstantynowicz J, Porowski T, Zoch-Zwierz W, Wasilewska J, Kadziela-Olech H, Kulak W, Owens SC, Piotrowska-Jastrzebska J, Kaczmarski M. A potential pathogenic role of oxalate in autism. Eur J Paediatr Neurol. 2012 Sep;16(5):485-91. doi: 10.1016/j.ejpn.2011.08.004. Epub 2011 Sep 10. PMID: 21911305.
[v] Marchini GS, Sarkissian C, Tian D, Gebreselassie S, Monga M. Gout, stone composition and urinary stone risk: a matched case comparative study. J Urol. 2013 Apr;189(4):1334-9. doi: 10.1016/j.juro.2012.09.102. Epub 2012 Sep 25. PMID: 23022002.
[vi] Ormanji MS, Rodrigues FG, Heilberg IP. Dietary Recommendations for Bariatric Patients to Prevent Kidney Stone Formation. Nutrients. 2020;12(5):1442. Published 2020 May 16. doi:10.3390/nu12051442
[vii] Garland V, Herlitz L, Regunathan-Shenk R. Diet-induced oxalate nephropathy from excessive nut and seed consumption. BMJ Case Rep. 2020 Nov 30;13(11):e237212. doi: 10.1136/bcr-2020-237212. PMID: 33257378; PMCID: PMC7705561.
[viii] Sitkin SI, Tkachenko EI, Vakhitov TY. METABOLIC DYSBIOSIS OF THE GUT MICROBIOTA AND ITS BIOMARKERS. Eksp Klin Gastroenterol. 2016 Jul;12(12):6-29. English, Russian. PMID: 29889418.
[ix] Patel M, Yarlagadda V, Adedoyin O, et al. Oxalate induces mitochondrial dysfunction and disrupts redox homeostasis in a human monocyte derived cell line. Redox Biol. 2018;15:207-215. doi:10.1016/j.redox.2017.12.003
[xi] Chen, Chien-Liang, et al. “Neurotoxic effects of carambola in rats: the role of oxalate.” Journal of the Formosan Medical Association 101.5 (2002): 337-341.
[xii] Konstantynowicz, J., Porowski, T., Zoch-Zwierz, W., Wasilewska, J., Kadziela-Olech, H., Kulak, W., Owens S.C., Piotrowska-Jastrzebska J., and Kaczmarski, M. (2012). A potential pathogenic role of oxalate in autism. European Journal of Paediatric Neurology, 16(5), 485-491.
[xiii] Molloy CA, Manning-Courtney P: Prevalence of chronic gastrointestinal symptoms in children with autism and autistic spectrum disorders. Autism 2003, 7(2):165-171.
[xiv] Nikolov Roumen N, Bearss Karen E, Jelle Letting E, Craig Erickson, Maria Rodowski, Aman Michael G, McCracken James T, McDougle Christopher J, Elaine Tierney, Benedetto Vitiello, Eugene Larnold, Bhavik Shah, Posey David J, Louise Ritz, Lawrence Scahill: Gastrointestinal Symptoms in a Sample of Children with Pervasive Developmental Disorders. J Autism Dev Disord 2009, 39:405-413.
[xv] Adams, J. B., Johansen, L. J., Powell, L. D., Quig, D., & Rubin, R. A. (2011). Gastrointestinal flora and gastrointestinal status in children with autism–comparisons to typical children and correlation with autism severity. BMC gastroenterology, 11(1), 22.
[xvi] Chapman, L. A. (2007). A Low Oxalate Diet for Autism.
[xvii] Waring, R. H., and L. V. Klovrza. “Sulphur metabolism in autism.” Journal of Nutritional and Environmental Medicine 10, no. 1 (2000): 25-32.
[xviii] Alberti, Antonino, Patrizia Pirrone, Maurizio Elia, Rosemary H. Waring, and Corrado Romano. “Sulphation deficit in “low-functioning” autistic children: a pilot study.” Biological psychiatry 46, no. 3 (1999): 420-424
[xix] Rossignol DA, Genuis SJ, Frye RE. Environmental toxicants and autism spectrum disorders: a systematic review. Transl Psychiatry. 2014;4(2):e360. Published 2014 Feb 11. doi:10.1038/tp.2014.4
[xx] Rossignol DA, Frye RE. A review of research trends in physiological abnormalities in autism spectrum disorders: immune dysregulation, inflammation, oxidative stress, mitochondrial dysfunction and environmental toxicant exposures. Mol Psychiatry. 2012;17:389–401.
[xxi] Crivelli JJ, Mitchell T, Knight J, et al. Contribution of Dietary Oxalate and Oxalate Precursors to Urinary Oxalate Excretion. Nutrients. 2020;13(1):62. Published 2020 Dec 28. doi:10.3390/nu13010062
[xxii] Holmes R.P., Goodman H.O., Assimos D.G., Schwille P.O., Messa P. Dietary oxalate and its intestinal absorption. Scanning Microsc. 1995;9:1109–1120.