What's the Difference Between CLA and Carnitine? Stabilizing the enzyme in fish odor syndrome L Carnitine: Everything You Need to Know Does L carnitine cause fishy body odor? Surprising Truth and Solutions Tonum 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. Breakthrough in studying the enzyme that ultimately produces fish odor syndrome EurekAlert!