Does Carnitine Cause Body Odor? Lume Deodorant Stabilizing the enzyme in fish odor syndrome L Carnitine: Uses, Benefits, Dosage, and Side Effects StrengthLog L Carnitine: Does it help with weight loss? 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. 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.