Oxalates are the salt form of oxalic acid, an acid that is found in many plant foods and can also be produced in the body.
Oxalic acid can form oxalate crystals when binding to minerals such as calcium. When deposited in the body, these can cause a lot of pain, similar to tiny glass shards.
This is probably most well-known with regards to kidney stones, which can often be oxalate/calcium stones.
There is also some evidence that excess oxalates could play a role in painful bladder conditions, such as interstitial cystitis. However, this evidence is more anecdotal than based on scientific studies (as there haven’t been any studies that I know of). Today I would like to look at some potential connections between oxalates and interstitial cystitis.