Acetyl L Carnitine Core Nutritionals Frontiers L Carnitine and Acetyl L Carnitine: Potential Novel Biomarkers for Major Depressive Disorder Could a mitochondrial metabolite known as acetyl L carnitine (LAC) yield a new biomarker for depression and potential new therapies? Dr. Carla Nasca, an @nyugrossman assistant professor of psychiatry and of neuroscience and physiology, Short chain carnitines in adolescent major depressive disorder: Associations and biomarker potential ScienceDirect