Carnitine: Genetic Variants Affecting Mitochondrial Energy and Health 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. L Carnitine: Everything You Need to Know Does L carnitine cause fishy body odor? Surprising Truth and Solutions Tonum Chocolate boosts happiness by increasing serotonin, a neurotransmitter that regulates mood and promotes calmness, and endorphins, the body's natural painkillers that create a sense of euphoria and reduce stress. 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.