TMAU: Diet to reduce a fishy odour Dietitian's Life Understanding the Side Effects of L Carnitine Injection and When to Seek Medical Advice L Carnitina: Beneficios y Contraindicaciones L carnitina: Qu es y para que sirve? VIG Microbiota and MalodorEtiology and Management 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.