How to Choose the Best L Carnitine Supplement: A Smart Shopper's Guide Life Extension L Carnitine 100mg ml 100ml First Choice Equine Frontiers L carnitine prevents lenvatinib induced muscle toxicity without impairment of the anti angiogenic efficacy 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