Oxalates

Oxalates are naturally occurring compounds found in various foods. Some common food sources that contain oxalates include:¹Attalla K, De S, Monga M. Oxalate content of food: a tangled web. Urology. 2014 Sep;84(3):555-60. doi: 10.1016/j.urology.2014.03.053.²Holmes RP, Kennedy M. Estimation of the oxalate content of foods and daily oxalate intake. Kidney Int. 2000 Apr;57(4):1662-7. doi: 10.1046/j.1523-1755.2000.00010.x.

1. Spinach: Spinach is known for its high oxalate content, making it one of the top contributors.
2. Rhubarb: Rhubarb, especially the leaves, contains significant amounts of oxalates.
3. Beet greens: The greens of beets also contain notable levels of oxalates.
4. Chard: Chard, a leafy green vegetable, contains moderate levels of oxalates.
5. Nuts and seeds: Certain nuts and seeds, such as almonds, cashews, and sesame seeds, contain oxalates.
6. Soy products: Foods like tofu, soy milk, and soybeans can have varying amounts of oxalates.
7. Chocolate: Dark chocolate, in particular, contains oxalates.
8. Tea: Certain types of tea, including black tea and green tea, contain oxalates.
9. Coffee.

Do I need to avoid oxalates?

Oxalates are naturally present in a range of foods that are rich in nutrients known to be beneficial for physical and mental health and shouldn’t be seen as a problem.³Petroski W, Minich DM. Is There Such a Thing as “Anti-Nutrients”? A Narrative Review of Perceived Problematic Plant Compounds. Nutrients. 2020 Sep 24;12(10):2929. doi: 10.3390/nu12102929. However, for people with certain health conditions it may be necessary to limit oxalate-rich foods as advised by their doctor or healthcare professional.⁴Mitchell 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.00373.2018.⁵Huang Y, Zhang YH, Chi ZP, Huang R, Huang H, Liu G, Zhang Y, Yang H, Lin J, Yang T, Cao SZ. The Handling of Oxalate in the Body and the Origin of Oxalate in Calcium Oxalate Stones. Urol Int. 2020;104(3-4):167-176. doi: 10.1159/000504417.

How can I reduce oxalates, if I chose to do that?

Cooking or boiling oxalate-rich foods can help reduce their oxalate content.⁶Chai W, Liebman M. Effect of different cooking methods on vegetable oxalate content. J Agric Food Chem. 2005 Apr 20;53(8):3027-30. doi: 10.1021/jf048128d. Additionally, recent research has found that adding vinegar to meals reduces the incidence of formation of calcium oxalate crystals in humans.⁷Zhu W, Liu Y, Lan Y, Li X, Luo L, Duan X, Lei M, Liu G, Yang Z, Mai X, Sun Y, Wang L, Lu S, Ou L, Wu W, Mai Z, Zhong D, Cai C, Zhao Z, Zhong W, Liu Y, Sun Y, Zeng G. Dietary vinegar prevents kidney stone recurrence via epigenetic regulations. EBioMedicine. 2019 Jul;45:231-250. doi: 10.1016/j.ebiom.2019.06.004.

It is crucial to remember that individual tolerance to diatary oxalates does vary from person to person. This can depend on the levels of Oxalobacter in their gut. Oxalobacter is a beneficial gut microbe with a remarkable ability to degrade oxalate. By breaking down dietary oxalate, Oxalobacter helps prevent the formation of oxalate crystals, which can contribute to the development of kidney stones. Its presence in the gut also contributes to a balanced and diverse gut microbiome, which is essential for optimal digestion, nutrient absorption, and immune function. Oxalobacter and Lactobacillus can often work symbiotically to produce enzymes that help to break down oxalate salts.⁸Sadaf H, Raza SI, Hassan SW. Role of gut microbiota against calcium oxalate. Microb Pathog. 2017 Aug;109:287-291. doi: 10.1016/j.micpath.2017.06.009. Therefore, Lactobacillus levels also need to be taken into consideration when assessing a person’s tolerance to dietary oxalates. Please consult with a healthcare professional before cutting down or cutting out oxalate-rich foods.

Synonyms: oxalate-containing foods, oxalate-rich foods, foods containing oxalates, oxalate salts, calcium oxalate

Important disclaimer

The Chuckling Goat Gut Microbiome Handbook is an educational resource built to translate complex science into plain English. The information provided on this page is not intended to be a substitute for professional medical advice, diagnosis, or treatment. Always seek the advice of your GP or other qualified health provider with any questions you may have regarding a medical condition. Always check with your GP for interactions with medications/health conditions before changing your diet or starting to take food supplements.

References

• 1
  Attalla K, De S, Monga M. Oxalate content of food: a tangled web. Urology. 2014 Sep;84(3):555-60. doi: 10.1016/j.urology.2014.03.053.
• 2
  Holmes RP, Kennedy M. Estimation of the oxalate content of foods and daily oxalate intake. Kidney Int. 2000 Apr;57(4):1662-7. doi: 10.1046/j.1523-1755.2000.00010.x.
• 3
  Petroski W, Minich DM. Is There Such a Thing as “Anti-Nutrients”? A Narrative Review of Perceived Problematic Plant Compounds. Nutrients. 2020 Sep 24;12(10):2929. doi: 10.3390/nu12102929.
• 4
  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.
• 5
  Huang Y, Zhang YH, Chi ZP, Huang R, Huang H, Liu G, Zhang Y, Yang H, Lin J, Yang T, Cao SZ. The Handling of Oxalate in the Body and the Origin of Oxalate in Calcium Oxalate Stones. Urol Int. 2020;104(3-4):167-176. doi: 10.1159/000504417.
• 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. doi: 10.1021/jf048128d.
• 7
  Zhu W, Liu Y, Lan Y, Li X, Luo L, Duan X, Lei M, Liu G, Yang Z, Mai X, Sun Y, Wang L, Lu S, Ou L, Wu W, Mai Z, Zhong D, Cai C, Zhao Z, Zhong W, Liu Y, Sun Y, Zeng G. Dietary vinegar prevents kidney stone recurrence via epigenetic regulations. EBioMedicine. 2019 Jul;45:231-250. doi: 10.1016/j.ebiom.2019.06.004.
• 8
  Sadaf H, Raza SI, Hassan SW. Role of gut microbiota against calcium oxalate. Microb Pathog. 2017 Aug;109:287-291. doi: 10.1016/j.micpath.2017.06.009.

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