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! Stabilizing the enzyme in fish odor syndrome 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. Potential Adverse Effects of L Carnitine Marnys