L carnitine: Science Backed Benefits, Risks, and More 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 cause fishy body odor? Surprising Truth and Solutions Tonum When to take L carnitine: Dosage, forms, and side effects Stabilizing the enzyme in fish odor syndrome