When nutraceuticals show benefit as antidepressant add ons, it's usually not because they're acting like drugs. Most antidepressants target neurotransmitters. Response is often limited by other factors (inflammation, nutrient status, energy metabolism Acetyl L Carnitine Tablets NOW Foods Frontiers L Carnitine and Acetyl L Carnitine: Potential Novel Biomarkers for Major Depressive Disorder Short chain carnitines in adolescent major depressive disorder: Associations and biomarker potential ScienceDirect PDF) Combined Antidepressant Effect of Acetyl L Carnitine and Bupropion against Experimental Animal Model Acetyl L Carnitine (Acetil L Carnitina)