L Carnitine Benefits, Uses, Dosage, Foods, Side Effects Dr. Axe Optimized Carnitine, 60 capsules Life Extension Acetyl l carnitine plus propionyl l carnitine improve efficacy of sildenafil in treatment of erectile dysfunction after bilateral nerve sparing radical retropubic prostatectomy Urology Rexdrive Amino with L Arginine HCl, L Citrulline, Acetyl L Carnitine Arginate DiHydrochloride, and Glycine Carnitine Heart and brain health Life Extension Europe 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.