REVIEW Acetyl-L-carnitine or ALCAR, is an acetylated form of L-carnitine (a betaine derivative of beta-hydroxybutyrate, is found in virtually all cells of higher animals and also in some microorganisms and plants. In animals it is synthesized almost exclusively in the liver). Acetylcarnitine is broken down in the blood by plasma esterases to carnitine which is used by the body to transport fatty acids into the mitochondria for breakdown.
During strenuous exercise, a large portion of L-carnitine and unused acetyl-CoA are converted to ALCAR and CoA inside mitochondria by carnitine O-acetyltransferase.The ALCAR is transported outside the mitochondria where it converts back to the two constituents. The L-carnitine is cycled back into the mitochondria with acyl groups to facilitate fatty acid utilization, but excess acetyl-CoA may block it.Excess acetyl-CoA causes more carbohydrates to be used for energy at the expense of fatty acids. This occurs by different mechanisms inside and outside the mitochondria. ALCAR transport decreases acetyl-CoA inside the mitochondria, but increases it outside.Glucose metabolism in diabetics improves with administration of either ALCAR or L-carnitine.] ALCAR decreases glucose consumption in favor of fat oxidation in non-diabetics. A portion of L-carnitine is converted to ALCAR after ingestion in humans.
ALC represents a compound of great interest for its wide clinical application in various neurological disorders: it may be of benefit in treating Alzheimer's dementia, depression in the elderly, HIV infection, chronic fatigue syndrome, peripheral neuropathies, ischemia and reperfusion of the brain, and cognitive impairment associated with various conditions.
Acetyl-L-carnitine is also used as a dietary supplement as a more orally available precursor to L-carnitine in regards to carbohydrate and fat metabolism.
Mingorance C, Rodríguez-Rodríguez R, Justo ML, Alvarez de Sotomayor M, Herrera MD, Critical update for the clinical use of L-carnitine analogs in cardiometabolic disorders. Vasc Health Risk Manag. 2011;7:169-76.
[No authors listed] Acetyl-L-carnitine. Monograph. Altern Med Rev. 2010 Apr;15(1):76-83.
Rosca MG, Lemieux H, Hoppel CL. Mitochondria in the elderly: Is acetylcarnitine a rejuvenator? Adv Drug Deliv Rev. 2009 Nov 30;61(14):1332-42.