Early research into L carnitine was often cited as underwhelming, showing negligible changes in muscle carnitine content and fat loss outcomes. However, these findings may have been limited by a short study window Healthy According to a randomized, double blind, placebo controlled clinical trial published in Elsevier journal Research in Autism Spectrum Disorders (2013), l carnitine supplementation demonstrated a significant therapeutic benefit in children 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 L Carnitine Force Factor