Stabilizing the enzyme in fish odor syndrome Trimethylamine N Oxide (TMAO) and cancer risk: Insights into a possible link 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. Get Rid of Fishy L Carnitine Smell: Essential Fixes Tonum Breakthrough in studying the enzyme that ultimately produces fish odour syndrome Trimethylaminuria: FMO3 mutations that cause malodorous body odor