Calcium oxalate
Calcium oxalate is a chemical compound. It is the calcium salt of oxalic acid. It has the chemical formula CaC2O4 or Ca(COO)2. It can be found as a dry form, or one of several hydrates.
Calcium oxalate can be found as both a mineral and in living things. Plants can make calcium oxalate out of extra calcium from the soil. In humans, it is the most common chemical in kidney stones.
Occurrence
[change | change source]Calcium oxalate is most commonly found as the monohydrate, Ca(COO)2·H2O. As a mineral, this is called whewellite. There are also dihydrate (Ca(COO)2·2 H2O) and trihydrate (Ca(COO)2·3 H2O) forms.
Calcium oxalate occurs naturally in many plants as a way of storing extra calcium. In some species, like pineapples, it forms sharp crystals called raphides. Along with the enzyme bromelain, these crystals may help protect the plants from herbivores.[1] Calcium oxalate is the most common oxalate found in lichens.[2]
Calcium oxalate is oxidised into calcium carbonate by living things, especially bacteria.[3]
Human health
[change | change source]Having too much oxalate in the body is called hyperoxaluria, and can lead to a kidney failure called oxalosis.[4]
Oxalate is absorbed by water during cooking, with boiling being the most effective.[5]
Calcium oxalate in urine can crystallise into kidney stones. Calcium oxalate is a metabolite of ethylene glycol and is involved in ethylene glycol poisoning.[6]
Sources
[change | change source]- ↑ Haleh Cohn (2023-05-26). "Why Does Pineapple Make Your Mouth Tickle?". McGill University Press. Retrieved 2025-08-05.
- ↑ Krajanová, Viktória (2023). "Discoveries and identification methods of metal oxalates in lichens and their mineral associations: A review of past studies and analytical options for lichenologists". Fungal Biology Reviews. 43 100287. Bibcode:2023FunBR..4300287K. doi:10.1016/j.fbr.2022.09.003.
- ↑ Cailleau, Guillaume; Mota, Matteo; Bindschedler, Saskia; Junier, Pilar; Verrecchia, Eric P. (2014). "Detection of active oxalate–carbonate pathway ecosystems in the Amazon Basin: Global implications of a natural potential C sink". Catena. 116: 132–141. Bibcode:2014Caten.116..132C. doi:10.1016/j.catena.2013.12.017.
- ↑ "Hyperoxaluria and oxalosis". Mayo Clinic. Retrieved 2025-08-05.
- ↑ Chai, Weiwen; Liebman, Michael (2005). "Effect of Different Cooking Methods on Vegetable Oxalate Content". Journal of Agricultural and Food Chemistry. 53 (8): 3027–3030. Bibcode:2005JAFC...53.3027C. doi:10.1021/jf048128d. PMID 15826055.
- ↑ Pomara, Cristoforo; Fiore, Carmela; d'Errico, Stefano; Riezzo, Irene; Fineschi, Vittorio (2008). "Calcium oxalate crystals in acute ethylene glycol poisoning: A confocal laser scanning microscope study in a fatal case". Clinical Toxicology. 46 (4): 322–324. doi:10.1080/15563650701419011. PMID 18363130.