Alt Med Rev. Nat Med. Lucky for the vegans in the house, our bodies can L-cwrnitine make it. Journal of LL-carnitine International Society of Sports Nutrition volume 17Article number: L-carnnitine Cite Anx article. Rest and rejuvenate details. L-carnitine Natural pain management is used as a supplement by recreationally-active, competitive and highly trained athletes. This systematic review aims to evaluate the effect of prolonged LC supplementation on metabolism and metabolic modifications. A literature search was conducted in the MEDLINE via PubMed and Web of Science databases from the inception up February The initial search retrieved articles, and a total of 11 studies were finally included after applying inclusion and exclusion criteria.