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. The Right Way to Take L Carnitine to Boost Your Training 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. PDF) [L carnitine treatment and fish odor syndrome: an unwaited adverse effect]. Is L Carnitine Safe? Watch FIRST BEFORE Taking L Carnitine Supplements