Nootropic Dietary Supplement Gluten Free Nutrition Non Gmo Supports Energy Metabolism Supports Alertness and Mental Focus Acetyl L-Carnitine (ALC) is a nutrient and naturally occurring metabolite in the human body that is involved in macronutrient metabolism. Deficiencies in L-Carnitine can increase fatigue and decrease recovery rate following physical activity. A number of tissues contain significant concentrations of ALC but these decrease as we age and there is evidence that dietary supplementation can address these shortfalls.