L Carnitine is Underrated. New Meta Review Reminds Us Why. Portal vein enriched metabolites as intermediate regulators of the gut microbiome in insulin resistance: Cell Metabolism Muscle Specific Deletion of Carnitine Acetyltransferase Compromises Glucose Tolerance and Metabolic Flexibility ScienceDirect Combining Berberine and L Carnitine can be beneficial for weight management, metabolism, and overall health. Berberine may improve insulin sensitivity, lower blood sugar, and support weight loss, while L carnitine helps the body use l carnitine: Nutrition, pathology, and health benefits ScienceDirect L carnitine tartrate supplementation in the fight against infectious disease