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. Does L Carnitine Work for Fat Loss? A Dietitian Explains Trimethylaminuria: Understanding and Treating Fish Odor Syndrome Understanding the Role of Carnitine in TPN and IDPN Therapy L Carnitine (Orange) Outlastlabz Breakthrough in studying the enzyme that ultimately produces fish odor syndrome EurekAlert!