TAAR1 and irritable bowel syndrome: Indeed, in patients with diarrhoea-predominant IBS, elevated levels of faecal β-PEA and tryptamine were associated with severity of diarrhoeal symptoms, while elevated peripheral 5-HT levels (induced via β-PEA/tryptamine-TAAR1 signalling) directly implicates altered trace aminergic signalling in IBS pathology (Zhai et al. 2023).