Can choline supplementation cause a fishy body odor? Consensus Does Carnitine Cause Body Odor? Lume Deodorant L carnitine supplements can cause a fishy odor in the breath, sweat, and urine. This is likely due to the formation of trimethylamine (TMA). TMA is also responsible for the pungent smell of Origins and metabolism of trimethylamine in humans Download Scientific Diagram Trimethylaminuria: Definition, symptoms, 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.