Why does L carnitine smell like fish food 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. Why Does L Carnitine Smell Like Fish TikTok 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. Acetyl L carnitine is a white crystalline solid that resembles snow. It has a mild odor similar to vinegar. It is a metabolite of L carnitine, derived from the amino acid L lysine in a series