Frontiers Discovery and validation of acetyl L carnitine in serum for diagnosis of major depressive disorder and remission status through metabolomic approach L Carnitine Shows Promise as Supportive Therapy for Autism A clinical trial published in the journal Research in Autism Spectrum Disorders found that l carnitine supplementation may help reduce autism symptoms in children. The Acetyl L Carnitine, 500 mg, 120 Vegetarian Capsules What is the beneficial dose of L Carnitine (L Carnitine) for Autism Spectrum Disorder (ASD)?