L Carnitine Creatine sits in that interesting category of supplements that are powerful in one lane and irrelevant in another. It's excellent for short burst muscular performance. It may have cognitive benefits. But it doesn't Exploring the potential anti thyroid activity of Acetyl L carnitine: Lactoperoxidase inhibition profile, iodine complexation and scavenging power against H2O2. Experimental and theoretical studies ScienceDirect L Carnitine Benefits, Sources, and Side Effects If you are like a lot of people, you may have never heard of carnitine but this important nutrient is critical for our body's ability to optimally burn fat required for energy.