Acetyl L Carnitine vs L Carnitine: 4 Key Differences Momentous 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 Comparison of short term and long term effects of peroral L carnitine intake: clinical implications of elevated TMAO levels in cardiovascular complications Frontiers The effect of L carnitine supplementation on lipid profile in adults: an umbrella meta analysis on interventional meta analyses