Acetyl-L-carnitine is the acetylated ester of the amino acid L-carnitine. Acetyl-L-carnitine is an endogenous mitochondrial membrane compound that helps maintain mitochondrial bioenergetics and lowers the increased oxidative stress associated with aging. Acetyl-L-carnitine and L-carnitine are absorbed into the bloodstream efficiently. Both are effective at carrying long-chain fatty acids across the membrane into the mitochondria where they are burned for energy production and utilized efficiently by the cells. Acetyl-L-carnitine also crosses the blood-brain barrier and guards against oxidative damage. Amyloid-beta peptide is a principal component of plaques and is thought to be a contributor to the aging process. Acetyl-L-carnitine exerts protective effects against such neurotoxicity and oxidative stress.