Systemic regulation of L carnitine in nutritional metabolism in zebrafish, Danio rerio Scientific Reports B6 vs B12 vs Niacinamide vs Gylcine vs L Caritine vs etc. : r tirzepatidecompound L Carnitine Oral Bioavailability NOW l Carnitine Supplement 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