Investigating the Association between Low Trimethylamine N Oxide Level TACG Dove Medical Press Human model of primary carnitine deficiency cardiomyopathy reveals ferroptosis as a novel mechanism: Stem Cell Reports L Carnitine Linus Pauling Institute Oregon State University 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. When a 12 month old boy in Portugal developed an unexpected and persistent smell similar to rotting fish, his parents were unsettled. The child appeared healthy, showed no signs of infection, and behaved normally. What are the benefits and side effects of L carnitine (Levocarnitine)?