An Oxalate Overview
Oxalates, also referred to as oxalic acid, are organic compounds that naturally occur in a wide variety of plants, including everything from leafy greens, legumes, nuts, and seeds, to cruciferous vegetables, blueberries, and dark chocolate. In small quantities, the body can also create oxalates by metabolizing vitamin C.
They are essentially a protective measure that plants have to defend themselves against predators. Like lectins and phytates, oxalates are considered to be antinutrients because once consumed, they tend to bind to minerals, like calcium or iron, forming oxalate compounds and causing the minerals to be non-bioavailable and therefore not useful to the body from a nutritional standpoint.
In fact, most of this chemical binding occurs in the colon, kidneys or in the urinary tract and these once-useful minerals are then eliminated in the stool or urine.
In addition to causing reduced absorption of vital minerals, oxalates are linked to a number of other health problems. Sensitivities that have been linked to high-oxalate consumption include the following:
- An increase in the formation of kidney stones
- Vulvodynia or any chronic, unexplained vulvar pain syndrome
- A carcinogenic effect on breast tissue cells
- Autism Spectrum Disorder
Let’s take a look at the science behind each of these links, and then explore some simple behavioral changes that may benefit those who are sensitive to oxalates.
Having a diet high in oxalates has been shown to increase the oxalate levels in urine and the general scientific consensus is that higher urinary oxalate levels increase the risk of developing kidney stones, or nephrolithiasis, in susceptible individuals. This is thought to happen when oxalates combine with calcium to form crystals which then leads to the formation of kidney stones. This particularly seems to be the case for individuals who have high urinary concentration of oxalates with low-volume output of urine, known as hyperoxaluria. (1)
Vulvodynia is a chronic pain syndrome of the vulva. It is characterized by prolonged vulvar pain that interferes with everyday living and working. Sexual intercourse, tight-fitting clothing, and prolonged sitting can cause pain for many women who suffer from vulvodynia.
The science behind whether oxalates play any role in vulvodynia is actually mixed. A study of 130 women with vulvodynia analyzed urine samples over a 24-hour period and 59 women who were determined to have hyperoxaluria were put on a low-oxalate diet and calcium citrate supplementation for three months. After this period, 14 women, or 24-percent, demonstrated an objective positive response, but only 6 of them, or 10-percent, said that they could have sexual intercourse without pain. These results led researchers to conclude that urinary oxalates may be an irritant for some with vulvodynia, but they are unlikely to be the primary cause. (2)
As it has been shown that excess oxalate can cause epithelial reactions similar to those seen in vulvodynia, a separate case study looked at a woman who had vulvodynia and exhibited periodic hyperoxaluria and high urinary pH. She was given calcium citrate supplementation to reduce urinary oxalate concentrations and within one year, she was able to resume normal work, sexual and recreational activities without pain. When the calcium citrate was removed, she experienced a return of her symptoms. These findings suggest that in some women, oxalates may play a role in their vulvodynia. (3)
A study from 2015 found that normal breast epithelial cells were transformed into breast cancer tumor cells with chronic exposure to oxalates, and oxalates had a carcinogenic effect that induced tumor formation when it was injected into the mammary cells of mice. (4)
Autism Spectrum Disorder
With respect to Autism Spectrum Disorder, ASD, a study conducted in 2012 found that in comparison to neurotypical children, children with ASD showed 3 times higher plasma oxalate levels and 2.5 times higher urinary oxalate concentrations. The researchers concluded that this variation may mean that hyperoxalemia and hyperoxaluria play a role in the pathogenesis of ASD. Further testing would need to be conducted to understand whether these differences are the result of impaired renal excretion, excessive oxalate absorption in the intestines, a central nervous system disturbance from oxalates crossing the blood brain barrier or a combination of any or all of these possibilities. (5)
It All Leads Back to the Gut
Even though the science is not definitive, knowing that oxalates may play a role in these conditions, along with the potential for oxalates to cause mineral deficiencies, many individuals could benefit by considering how oxalates may be affecting them and then by taking steps to reduce their consumption of oxalates to see if it helps to mitigate or relieve any negative symptoms.
Many foods that are high in oxalates are actually very healthy and have been shown to positively affect cardiovascular health, causing the medical community to recommend a low-oxalate diet, a diet that restricts oxalate intake to less than 100 mg/day, only in cases where hyperoxaluria is present.
This can easily be done by restricting the intake of common foods that are very high in oxalate, including:
- wheat bran
- beets. (1)
Alter Your Cooking Methods
Despite the apparent health benefits of green smoothies and fresh juices, for individuals who are susceptible to conditions that may be aggravated by oxalate consumption, it may be wise to reduce the consumption of green juices as the oxalate concentration in raw leafy greens is quite high. Additionally, it has been shown that boiling spinach, potatoes and other high-oxalate foods prior to eating them significantly reduces the oxalate content in comparison to other food preparation methods, including steaming and baking. (6)
Oxalate Dumping – A Word of Caution
It’s important to remember that oxalates are a toxin that accumulate in the body, typically as salt crystals within various epithelial tissues, so when dietary oxalates are decreased, the oxalate concentration of the blood will decrease and will elicit an elimination of the accumulated toxins from the tissues. This is the general mechanism the body has for any pharmacologic, dietary or environmental toxin, and is the primary reason why so many dietary changes result in a detox syndrome. With respect to oxalates, this detox process, referred to as oxalate dumping, can cause a whole host of uncomfortable symptoms and is typically seen within 3 days to 2 weeks of significantly reducing oxalate intake.
Anecdotal evidence collected by dietary clinicians and offered up by countless patients that have significantly reduced their intake of oxalates or those who have transitioned to the all-meat ‘carnivore diet’ list the following as possible symptoms of oxalate dumping:
- General cold-like symptoms: runny nose, sneezing, sore throat, mucus congestion and ear pain
- Eye symptoms: dry, gritty eyes, runny eyes, puffy eyelids, stabbing eye pain, blurry vision and stys
- Digestive upset, diarrhea or constipation, and painful gritty stool
- Urinary frequency, urgency and kidney stones
- Skin symptoms: skin eruptions, rash on the palate or throat, canker sores on lips or tongue, vulvar itching and pain
- Joint pain often in the shoulders, hips and knees, along with trigger finger, foot pain and restless legs
- Generalized detox symptoms: headache or pulsating headache, tinnitus, feeling vibrations, heart palpitations, sleep disturbances and anxiety
Reducing the Discomfort
Similar to other detox processes within the body, these symptoms typically last between 3-7 days. Though it is temporary, being run down, sick or out of sorts is never fun. One of the best ways to combat this detox is to take the withdrawal of oxalates slow. Keep a food diary of your typical diet and use it to calculate your baseline average daily intake of oxalates. If your end goal is to reach 100 mg/day or lower, reduce this incrementally dropping 10 mg/day every 5-7 days depending on the severity of any detox symptoms. Though it does take additional planning and work, this should allow your body to dump the accumulated oxalate more slowly, minimizing the negative symptoms and allowing your body to adjust to the dietary changes.
Along with this, oxalate dumping symptoms can be mitigated by staying hydrated, getting adequate sleep, taking epsom salt baths and utilizing supplemental support from calcium citrate (7), magnesium, vitamin B6, and oxalate-degrading probiotics. (8)
So even though the scientific jury is still out on the specific role oxalates play in various disorders and diseases, if you suffer with symptoms that suggest oxalates could be an aggravating factor, be proactive and ask for a test that can determine if you have hyperoxaluria, take steps to make some simple dietary changes and consider supplementation choices that could help reduce the concentration of oxalates in your body. Take it slow to avoid the negative symptoms that come along with oxalate dumping, and after a brief detox period, tune in to your body and symptoms and see if any of the changes yield a positive outcome!
1. Worcester E, Coe F. Clinical Practice Calcium Kidney Stones. N Engl J Med. 2010 Sep 2; 363(10):954–963.
2. Baggish M, Sze E, Johnson R. Urinary oxalate excretion and its role in vulvar pain syndrome. Am J Obstet Gynecol. 1997 Sep;177(3):507-11.
3. Solomons C, Melmed M, Heitler S. Calcium citrate for vulvar vestibulitis. A case report. J Reprod Med. 1991 Dec;36(12):879-82.
4. Castellaro A, Tonda A, Cejas H, Ferreyra H, Caputto B, Pucci O, et al. Oxalate induces breast cancer. BMC Cancer. 2015 Oct 22;15:761.
5. Konstantynowicz J, Porowski T, Zoch-Zwierz W, Wasilewska J, Kadziela-Olech H, Kulak W, et al. A potential pathogenic role of oxalate in autism. Eur J Paediatr Neurol. 2012 Sep;16(5):485-91.
6. Chai W, Liebman M. Effect of different cooking methods on vegetable oxalate content. J Agric Food Chem. 2005 Apr 20;53(8):3027-30.
7. The Great Plains Laboratory, Inc. Oxalates Control is a Major New Factor in Autism Therapy. [Internet]. [cited 13th October 2019]. Available from: https://www.greatplainslaboratory.com/articles-1/2015/11/13/oxalates-control-is-a-major-new-factor-in-autism-therapy
8. Liebman M, Al-Wahsh I. Probiotics and Other Key Determinants of Dietary Oxalate Absorption. Adv Nutr. 2011 May;2(3):254–260.0