Oxalic acid (oxalate): What it is, risks, how to avoid it, and more Health ConditionsHealth ConditionsAlzheimer's & DementiaAnxietyArthritisAsthma & AllergiesBreast CancerCancerCardiovascular HealthCOVID-19Dermatology & SkincareDiabetesEnvironment & SustainabilityExercise & FitnessEye HealthHeadache & MigraineHealth EquityHIV & AIDSHuman BiologyInflammatory Bowel DiseaseLeukemiaLGBTQIA+Men's HealthMental HealthMultiple Sclerosis (MS)NutritionParkinson's DiseasePsoriasisSexual HealthWomen's HealthDiscoverNewsLatest NewsOriginal SeriesMedical MythsHonest NutritionThrough My EyesNew Normal HealthPodcastsHow to understand chronic painWhat is behind vaccine hesitancy?The amazing story of hepatitis C, from discovery to cureNew directions in dementia researchCan psychedelics rewire a depressed, anxious brain?Why climate change matters for human healthToolsGeneral HealthDrugs A-ZHealth HubsHealth ToolsBMI Calculators and ChartsBlood Pressure Chart: Ranges and GuideBreast Cancer: Self-Examination GuideSleep CalculatorHealth ProductsAffordable Therapy OptionsBlood Pressure MonitorsDiabetic SuppliesFitness TrackersHome GymsGreen Cleaning ProductsHow to Shop for CBDQuizzesRA Myths vs FactsType 2 Diabetes: Managing Blood SugarAnkylosing Spondylitis Pain: Fact or FictionConnectAbout Medical News TodayWho We AreOur Editorial ProcessContent IntegrityConscious LanguageNewslettersSign UpFollow UsMedical News TodayHealth ConditionsDiscoverToolsConnectSubscribe What is oxalic acid oxalate and is it dangerous Medically reviewed by Jared Meacham, Ph.D., RD, PMP, MBA, CSCS — By Zia Sherrell, MPH on July 20, 2022Many fruits, vegetables, nuts, and whole grains contain a naturally occurring compound called oxalic acid, which people sometimes refer to as oxalate. Although small amounts of oxalic acid are not harmful, this compound can inhibit the absorption of other important nutrients. For this reason, some people refer to oxalic acid as an anti-nutrient. In some people, it can also increase the risk of kidney stones. Certain gut bacteria can metabolize, or break down, oxalic acid. This prevents it from binding to minerals and affecting nutrient absorption. This article looks at oxalic acid and its associated risks in more detail. It also lists dietary sources of the compound and explains how people can decrease their intake. What is it Share on PinterestFlavia Morlachetti/Getty ImagesOxalic acid is a common organic compound. A range of living organisms — including fungi, bacteria, plants, animals, and humans — produce it. Technically, oxalate occurs when the oxalic acid in plants binds to minerals. However, many people use the terms interchangeably. The body can either produce oxalate as a waste product or obtain it from the diet. Oxalate can combine with other minerals in the body to form compounds such as calcium oxalate and iron oxalate. People can then eliminate these oxalate compounds in the urine or stool. However, some individuals with high oxalate levels may develop kidney stones. What is it used for Although oxalic acid naturally occurs in plants and humans, it also has a variety of uses in industry. These uses include:removing rustremoving stainsstripping and cleaningremoving waxcleaning wooddyeing textiles Laboratories may also use oxalic acid and oxalate salts as anticoagulants in blood specimens. Health risks In small amounts, oxalate is harmless. However, higher levels may reduce the body’s mineral absorption and contribute to kidney stone formation. Nutrient absorption People refer to oxalates as anti-nutrients. This is because they bind to certain minerals and prevent the body from absorbing and utilizing them. One good example is spinach. Although it is rich in the important nutrients calcium and magnesium, it is also high in oxalate. The oxalate forms a complex with these minerals and can inhibit absorption. Kidney stones The other concern with oxalate is that it can contribute to kidney stones. Most people have a small amount of oxalate and calcium in the urinary tract at some point. Usually, they remain dissolved, and there are no associated problems. However, in some people, the compounds form crystals and then kidney stones. Research has shown that this is a particular problem if oxalate levels are high and urinary volume is low. There are several types of kidney stones, which comprise different minerals, but calcium oxalate is the most common. Therefore, if a person is prone to developing kidney stones, their doctor may advise them to reduce their intake of oxalate-rich foods. They should also consume enough calcium and avoid vitamin C supplements. Learn more about kidney stones. The gut and oxalate absorption Certain bacteria in the digestive system can metabolize some dietary oxalate before it binds to minerals. This process can prevent oxalate’s potentially harmful effects. A type of gut bacteria called Oxalobacter formigenes breaks down oxalate and uses it as energy. Having this bacteria in the gut microbiome significantly reduces the amount of oxalate in a person’s body. Many people have O. formigenes in their gut. According to research, it is present in the feces of about 60–80% of adults. Some people who experience recurrent calcium oxalate kidney stones have less of this bacteria. Certain factors, such as taking antibiotics, can reduce the number of good bacteria in the gut. Additionally, people with altered gut function, such as those with inflammatory bowel disease (IBD), have an increased risk of developing kidney stones. How people consume it People typically consume oxalate through dietary sources. Almost all plants, including fruits and vegetables, contain oxalates, having the highest concentration in the leaves and seeds. However, the amount they contain varies considerably. Vegetables that are particularly high in oxalate include:spinachkaleswiss chardsweet potatoesrhubarbbeetspotato skins Other dietary sources rich in oxalate include:black teasoycocoanuts, such as almonds, Brazil nuts, and pine nuts The amount the body can absorb from foods depends on the quantity of soluble oxalates the foods contain and the bioavailability of these oxalates. For example, tea has a significantly higher rate of oxalate absorption than spinach or rhubarb. The method of food preparation and cooking can also affect the oxalate content. Soaking certain vegetables and legumes can reduce the amount of oxalate they contain. How to avoid it The best way to avoid oxalate is to reduce the intake of oxalate-rich foods. It is important to eat a variety of fruits and vegetables. However, if a person is concerned about the number of oxalates in certain foods, they can replace them with low oxalate alternatives. Some examples include:High oxalate foodLow oxalate alternativekalebroccolispinachasparaguspotatoescauliflowerrhubarb applesbeetscherriesblack teafruit teadark chocolatewhite chocolate Boiling vegetables also reduces their oxalate content. Research shows that boiling could remove up to 76% of oxalates, depending on the vegetable. It is also important to eat enough dietary calcium. This mineral can bind to oxalate in the digestive system and reduce how much the body absorbs. Therefore, eating milk, yogurt, or cheese alongside foods containing oxalates can reduce the likelihood of developing issues such as kidney stones. Summary Oxalate is a compound present in many plant-based foods, including spinach, chard, and kale. In the digestive system, oxalate can form complexes with minerals such as calcium and interfere with their absorption. Additionally, a high oxalate diet may lead to some people developing kidney stones. Doctors may advise some individuals to consume a low oxalate diet. They can do this by replacing high oxalate foods with low oxalate alternatives, boiling vegetables, and eating foods rich in calcium alongside high oxalate foods. Last medically reviewed on July 20, 2022Biology / BiochemistryNutrition / Diet 13 sourcescollapsedMedical News Today has strict sourcing guidelines and draws only from peer-reviewed studies, academic research institutions, and medical journals and associations. We avoid using tertiary references. We link primary sources — including studies, scientific references, and statistics — within each article and also list them in the resources section at the bottom of our articles. You can learn more about how we ensure our content is accurate and current by reading our editorial policy.Akter, S., et al. (2020). Interactions between phytochemicals and minerals in Terminalia ferdinandiana and implications for mineral bioavailability.https://www.frontiersin.org/articles/10.3389/fnut.2020.598219/fullArias-Rico. J., et al. (2020). Study of edible plants: Effects of boiling on nutritional, antioxidant, and physicochemical properties.https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7278626/Calcium oxalate stones. (n.d.).https://www.kidney.org/atoz/content/calcium-oxalate-stoneD'Alessandro, C., et al. (2019). Which diet for calcium stone patients: A real-world approach to preventive care.https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6566930/Ganji-Arjenaki, M., et al. (2017). Nephrolithiasis as a common urinary system manifestation of inflammatory bowel diseases; a clinical review and meta-analysis.https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5607992/Joshi, V., et al. (2021). Regulation of oxalate metabolism in spinach revealed by RNA-seq-based transcriptomic analysis.https://www.ncbi.nlm.nih.gov/pmc/articles/PMC8157348/Kidney stone diet plan and prevention. (n.d.).https://www.kidney.org/atoz/content/dietMiller, A. W., et al. (2017). The induction of oxalate metabolism in vivo is more effective with functional microbial communities than with functional microbial species.https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5613171/Mitchell. T., et al. (2018). Dietary oxalate and kidney stone formation.https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6459305/Oxalic acid. (2004).https://pubchem.ncbi.nlm.nih.gov/compound/Oxalic-acidOxalobacter formigenes. (n.d.).https://www.sciencedirect.com/topics/immunology-and-microbiology/oxalobacter-formigenesPalmieri, F., et al. (2019). Chapter two - oxalic acid, a molecule at the crossroads of bacterial-fungal interactions [Abstract].https://www.sciencedirect.com/science/article/abs/pii/S0065216418300510Shi, L., et al. (2018). Changes in levels of phytic acid, lectins and oxalates during soaking and cooking of Canadian pulses [Abstract].https://pubmed.ncbi.nlm.nih.gov/29580532/FEEDBACK:Medically reviewed by Jared Meacham, Ph.D., RD, PMP, MBA, CSCS — By Zia Sherrell, MPH on July 20, 2022 Latest newsWhat sets 'SuperAgers' apart? Their unusually large neuronsOmega-3 may provide a brain boost for people in midlifeSeasonal affective disorder (SAD): How to beat it this fall and winterCDC: Monkeypox in the US 'unlikely to be eliminated in the near future'Why are more women prone to Alzheimer's? New clues arise Related Coverage29 nutrition tips for better health and longevityMedically reviewed by Grant Tinsley, PhD Good nutrition can help improve health and lower the risk of diseases at all ages. This article offers science-based nutrition tips for a healthier…READ MOREIron-rich foods for vegetarians and vegansMedically reviewed by Katherine Marengo LDN, R.D. Iron is an essential nutrient. 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