Updated: Jun 13
The trouble with oxalates
This is an important read for anyone with kidney stones, urinary issues, chronic joint or muscle pain, unusual rashes, or even autism. Could oxalate toxicity be the underlying cause?
Oxalate is a natural substance found in many plant foods.
In humans, when plant foods are consumed, oxalates are degraded by certain bacteria in the gut or removed from the body by being bound to minerals (particularly calcium and iron) in the intestines and are excreted in stool. Oxalate can also be removed from the body via the kidneys in urine.
Issues arise when there is too much oxalate to be excreted or if our gut doesn't contain enough of the oxalate degrading microbes.
One of the most common issues with increased oxalates in the urine (hyperoxaluria) is the formation of kidney stones. However, if the body struggles to eliminate oxalate it can accumulate as crystals anywhere in the body. Commonly it accumulates in blood, then the eyes, bones, skin, muscles, blood vessels, heart and other organs.
High oxalates have also been linked with autism and inflammatory bowel disease. It can also be an underlying issue in those with ongoing gut problems or irritable bowel syndrome.
Signs and symptoms of oxalate toxicity can include:
Pain, muscle aches & fatigue
Joint pain – if deposition of oxalate crystals is in synovial fluid or connective tissue.
Chronic UTIs, interstitial cystitis or kidney infections
Frequently cloudy or hazy urine
Vulvar pain in women
Gastrointestinal problems or irritable bowel
Recurring fungal infections
Sore eyes / poor vision
Excessive histamine signs and symptoms
Brain fog and fatigue
Excessive intake of high oxalate foods is often the underlying cause, particularly if combined with poor gut health, fat malabsorption, and certain nutrient deficiencies.
In rare circumstances, people can be endogenous producers of oxalate due to a genetic disorder or low vitamin B6.
What tests are used to assess for high oxalate?
24hr urine test showing high urinary oxalate (gold standard - particularly if adjusted for height in children)
Great Plains Laboratory Organic Acids Test (OATS) – also a urine test.
N.B. urinary tests may not be 100% accurate and give false negatives for those with sulfation problems. (Low sulfate inside kidney tubules could reduce the ability of the kidneys to remove oxalate from blood and deliver to urine. Those with autism and HIV are known to have high urinary wasting of sulfate).
What foods are very high in oxalates?
Unfortunately, many healthy foods are high in oxalates. Spinach is one of the worst offenders.
Nuts that are high in oxalates include peanuts, cashews, pine nuts, Macadamia nuts, almonds, pecans, hazelnuts, and walnuts.
Oxalates can also come from moulds, mycotoxins and fungi.
What else can increase oxalate levels or aggravate oxalate toxicity?