Frontiers Gut Metabolite Trimethylamine N Oxide in Atherosclerosis: From Mechanism to Therapy Breakthrough in studying the enzyme that ultimately produces fish odour syndrome Trimethylamine N Oxide (TMAO) and cancer risk: Insights into a possible link ScienceDirect Treatments of trimethylaminuria: where we are and where we might be heading ScienceDirect Did You Know? Some people report a fishy smell after supplementing with L carnitine. This happens because certain gut bacteria convert carnitine to trimethylamine, a malodorous compound found in rotting fish.