[2][5] Similar to melatonin but unlike other antioxidants, it scavenges radicals without subsequently generating reactive and pro-oxidant intermediate compounds.

[2][5][6] This compound is endogenously produced by human microbiota and has only been detected in vivo when the species Clostridium sporogenes is present in the gastrointestinal tract.

Peptostreptococcus species with a full fldAIBC gene cluster convert tryptophan into IPA and 3-indoleacrylic acid (IA) in vitro and protects against colitis in mice.

[17] In 2017, elevated concentrations of IPA in human blood plasma were found to be correlated with a lower risk of type 2 diabetes and higher consumption of fiber-rich foods.

[2][18][19] A separate study found that Roux-en-Y gastric bypass surgery increases the amount of IPA and indole sulfuric acid (ISA) in obese T2D patients.