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Oxalates - What Are They and How Do They Relate to Interstitial Cystitis?

Updated: Aug 11, 2022

Written by Stephanie Smith, Dietetic Intern and edited by Callie Krajcir, MS, RD

Ever hear people mention the word “oxalate” in a support group or on social media? This isn’t a typical word the Average Joe stumbles across on a daily basis.

If you eat food, you’re almost surely consuming oxalates in some amount. Oxalates are the salt form of oxalic acid, which is formed by many plant foods and produced in the body by the liver. Oxalates can form in the kidney, the bladder, and ureter. While oxalates do not pose harm to everyone, this post will provide an overview of how oxalates can relate to IC.

Oxalates and Pain in the Body

Oxalic acid can form crystals that cause pain to the body when they bind to minerals such as calcium. A common example of a large oxalate crystal causing pain to the body that you may have heard of before includes the formation of kidney stones. In addition, the formation of numerous small oxalate crystals in the urinary tract have the potential to cause pain and damage which has been theorized to lead to conditions such as vulvodynia, a condition in which oxalates are deposited in the vaginal tissue.

Factors that Contribute to Oxalate Formulation

  • Oxidative stress and certain genetic mutations

  • Dietary sources: specific plant-based sources that contain high quantities of oxalic acid (we'll get into this later)

  • Yeast overgrowth in the intestinal tract

While a variety of factors may contribute to the formation of oxalates in the body, the good news is there are various strategies that have been theorized to reduce the formation of oxalates in the body.

Magnesium Citrate

Supplementing 300 mg, the maximum of magnesium citrate, has the ability to inhibit the absorption of oxalates when consuming meals that are high in oxalates.


Nephure is an enzyme sold in the United States. Nephure Oxalate Reducing Enzyme may help users add back some of their earlier avoided foods due to low oxalate dieting.

Yeast and Bacteria

Given that an overgrowth of yeast in the intestinal tract can lead to oxalate formation, taking an antifungal to reduce the production of yeast can also prevent the formation of oxalates. Certain bacteria including bifidobacteria and lactobacilli can help degrade oxalates, therefore taking a bacterial supplement can be helpful.

Oxalobacter formigenes are bacteria that are very beneficial for oxalate degradation. Oxalobacter formigenes has been found in many animal species and in humans. While there is not a specific supplement established, people can obtain Oxalobacter formigenes through eating animal meats and fats since grass fed pastured animals carry the most nutrient density.

We can additionally take certain measures to reduce the elimination of Oxalobacter formigenes in our bodies. Moreover, chronic diarrhea has been proven to flush Oxalobacter formigenes in our bodies, therefore, it is important to keep diarrhea under control. Luckily, quality yogurts, made with whole milk and live cultures, are extremely effective means of stopping diarrhea. Recommended brands include Fage, Stonyfield, Seven Stars, and Nancy’s.

It is important to keep in mind that these bacteria are easily destroyed by antibiotics. Therefore, it may be beneficial to avoid antibiotics that Oxalobacter formigenes are known to be sensitive to including: Azithromycin, Ciprofloxacin, Clarithromycin, Clindamycin, Doxycycline, , Gentamicin, Levofloxacin, Metronidazole, Tetracycline.

Liver and Bile Support

Unabsorbed fats in individuals with fat maldigestion issues can bind to calcium and increase oxalate absorption in the body. For this population, consuming foods that support the liver and bile may improve fat digestion. Some of these items include bitters, taurine, lemon juice, milk thistle extract, and olive oil. While these items support the liver and bile, some of these items may not work well for individuals with IC and each of these items should only be consumed if tolerated.

Vitamin B-6

Since sufficient levels of vitamin B-6 are required for oxalate degradation, supplementation may be beneficial for individuals who do not consume adequate quantities via the diet. Vitamin B6 can be found in a variety of foods.

IC friendly sources of Vitamin B6 include: chickpeas (1.1 mg/1 cup), poultry (0.5 mg/3 oz), yellowfin tuna (0.9 mg/3 oz) salmon (0.6 mg/3 oz), cottage cheese (0.2 mg/1 cup), rice, squash (0.2 mg/1/2 cup), potatoes (0.4 mg/1 cup), nuts (0.1 mg/1 oz), and watermelon (0.1 mg/1 cup).

Foods High in Oxalates

Common Foods High in Oxalates
  • Spinach (raw or cooked)

  • Almonds

  • Wheat

  • Potatoes

  • Cashews

  • Dates

  • Raspberries

Other Foods High in Oxalates
  • Rhubarb

  • Bran (especially rice)

  • Buckwheat

  • Miso

  • Soy

  • Beetroot

  • Cocoa / chocolate

  • Brown rice flour

  • Cornmeal

  • Millet

  • Navy Beans

  • Okra

It is important to point out that many people with IC do not need to worry about oxalates, especially since doing so can be very restrictive.

Wondering if you should be concerned about oxalates? Ask your doctor or a Registered Dietitian if a low-oxalate diet is right for you. If it is determined that limiting foods high in oxalates can benefit you, limit consumption of high oxalate-containing foods to one item (from this list) each day.

Have questions? Send to

Looking for a Registered Dietitian that specializes in IC? Look no further. Callie Krajcir is a Registered Dietitian living with IC. To learn about her Road To Remission program and how it can help you minimize your IC symptoms, click here.


Cowley, H., Yan, Q., Koetzner, L., Dolan, L., Nordwald, E., & Cowley, A. B. (2017). In vitro and in vivo safety evaluation of NephureTM. Regulatory Toxicology and Pharmacology, 86, 241–252.

Plotner, B. (2020, November 29). Options with oxalate intolerances. Nourishing Plot.

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