Acetyl L carnitine erectile dysfunction: What the evidence and real world use actually show Potential Adverse Effects of L Carnitine Marnys Revisiting the Role of Carnitine in Heart Disease Through the Lens of the Gut Microbiota Trimethylaminuria: Understanding and Treating Fish Odor Syndrome The adverse effects of long term l carnitine supplementation on liver and kidney function in rats L Liu, D M Zhang, M X Wang, C Y Fan, F Zhou, S J Wang, L D Kong, 2015 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.