Functional differences between l and d carnitine in metabolic regulation evaluated using a low carnitine Nile tilapia model British Journal of Nutrition Cambridge Core Effects of l carnitine supplementation on liver and kidney lipid levels Download Scientific Diagram 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 L Carnitine