Can Acetyl L Carnitine Help Clear Brain Fog and Fatigue in Long COVID and ME CFS? RTHM L Theanine Vs L Carnitine: Can We Combine Them? Vinatura Supplements L Carnitine Side Effects & Safety: A Complete Guide The Science of Good Health CARNITINE (L CARNITINE, ACETYLCARNITINE) Neuroneeds Trimethylaminuria (Fish Odor Syndrome or TMAU) 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.