L Carnitine Oral Bioavailability NOW l Carnitine Supplement Can Acetyl L Carnitine Help Clear Brain Fog and Fatigue in Long COVID and ME CFS? RTHM L carnitine supplements bioavailability is very less and according to some studies it takes 8 to 12 weeks for for loss results, so if you decide to supplement with oral L carnitine do take it in The bright and the dark sides of L carnitine supplementation: a systematic review Journal of the International Society of Sports Nutrition Springer Nature Link