Oxalic Acid content in food
July 20 2017 by
Ray Sahelian, M.D.

Oxalic acid is a strong organic acid. The dianion form of oxalic acid is known as oxalate. Many metal ions form insoluble precipitates with oxalate, a well known example being calcium oxalate.

Calcium oxalate is the most common form of kidney stone.

Oxalic acid in food, dietary sources
Foods that contain a very high amount of oxalic acid. include black rhubarb stalks, pepper, amaranth, parsley,  spinach, chard, cocoa, chocolate, beets, most nuts, most berries, and beans.
Besides black tea, oxalate is found in spinach, rhubarb, nuts, wheat bran and chocolate. In rare cases, too much oxalate can lead to kidney trouble, but often there's also a contributing intestinal problem.

Danger, excess, caution, side effects
Am J Med. 2013. Oxalate nephropathy due to 'juicing': case report and review. A patient presented with oxalate-induced acute renal failure that was attributable to consumption of oxalate-rich fruit and vegetable juices obtained from juicing. We describe the case and also review the clinical presentation of 65 patients seen at Mayo Clinic (Rochester, MN) from 1985 through 2010 with renal failure and biopsy-proven renal calcium oxalate crystals. The cause of renal oxalosis was identified for all patients: a single cause for 36 patients and at least 2 causes for 29 patients. Three patients, including our index patient, had presumed diet-induced oxalate nephropathy in the context of chronic kidney disease. Identification of calcium oxalate crystals in a kidney biopsy should prompt an evaluation for causes of renal oxalosis, including a detailed dietary history. Clinicians should be aware that an oxalate-rich diet may potentially precipitate acute renal failure in patients with chronic kidney disease. Juicing followed by heavy consumption of oxalate-rich juices appears to be a potential cause of oxalate nephropathy and acute renal failure.

Doctors traced an Arkansas man's kidney failure to an unusual cause his habit of drinking a gallon of iced tea each day. The 56-year-old man's kidney problems may have started when he drank about 16 8-ounce cups of iced tea every day. Black tea has a chemical known to cause kidney stones or even kidney failure in excessive amounts. The unidentified man went to the hospital May 2014 with nausea, weakness, fatigue and body aches. Doctors determined his kidneys were badly clogged and inflamed by the food chemical oxalate. The man is now on dialysis, and likely will be for the rest of his life.

Research
Proc Natl Academy Sci USA. 2015. Oxalic acid and diacylglycerol 36:3 are cross-species markers of sleep debt. In humans, reduced sleep duration has been associated with risk for metabolic disorders, including weight gain, diabetes, obesity, and cardiovascular disease. In this study we used rat and human models to simulate modern-day conditions of restricted sleep and addressed cross-species consequences via comprehensive metabolite profiling. Serum from sleep-restricted rats was analyzed using polar and nonpolar methods in two independent datasets. A total of 38 features were changed across independent experiments, with the majority classified as lipids (18 from 28 identified). In a parallel human study, 92 metabolites were identified as potentially significant, with the majority also classified as lipids (32 of 37 identified). Intriguingly, two metabolites, oxalic acid and diacylglycerol 36:3, were robustly and quantitatively reduced in both species following sleep restriction, and recovered to near baseline levels after sleep restriction

Questions
Q. I've read anecdotal testimonials of cancer patients drinking 12 oz of carrot juice every 24 hours until their tumors were gone, much to the amazement of their physicians. The purported active ingredient is oxalic acid. The only scientific research I've found is a test done at NCI which did show a positive response with PURE oxalic acid. What do you think about this carrot juice cancer therapy? Or diets high in oxalic acid?
   A. We have not seen any studies regarding the human use of oxalic acid supplements in terms of cancer prevention or treatment. Carrot juice has a lot of carotenoids, and whether drinking lots of carrot juice is a form of cancer treatment has not been studied to the best of our knowledge. Just because a form of treatment has not been studied does not mean it is not effective. However, there's not much we can add if we don't have see any research on these topics.

Q. I am on a low oxalate diet. I need to know the oxalic acid value of turmeric curcumin. High oxalate foods cause me to have burning pain.
   A. We are not aware of turmeric curcumin having any oxalic acid.