L CARNITINE Ampoules Mesotherapy Serum for Body Treatments from Natude Dermishop L Carnitine for Weight Loss: How It Works, Dosage & Best Supplement Zeelab Pharmacy What Is L Carnitine: Benefits, Side Effects, & More Swolverine 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. If you are like a lot of people, you may have never heard of carnitine but this important nutrient is critical for our body's ability to optimally burn fat required for energy.