Potential Adverse Effects of L Carnitine Marnys 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. CUD Deficiency Primary Carnitine Deficiency 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. 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 Theres a reason why fish smell so bad! As a perfumer, Im a little sensitive to smells So I wondered why fish have such a strong fragrance, and why lemon seems to neutralize it So if youre a