L carnitine: Science Backed Benefits, Risks, and More The Role of l Carnitine in Mitochondria, Prevention of Metabolic Inflexibility and Disease Initiation L Carnitine: Unveiling the Science Behind its Role in Effective Weight Loss Aesthetics 360 Lash & MedSpa CUD Deficiency Primary Carnitine Deficiency L Carnitine Side Effects & Safety: A Complete Guide The Science of Good 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.