A. L-carnitine is an amino acid derivative of L-lysine and L-methionine. It is synthesized in the human body, the majority made in the liver and kidneys. L-carnitine plays a role in cellular energy production and has some antioxidant activity.† It's responsible for the transport of long-chain fatty acids across the inner mitochondrial membranes into the mitochondria. It also removes short-chain and medium chain fatty acids from the mitochondria. L-carnitine supplementation is primarily indicated for use in carnitine deficiency. Acetyl-L-carnitine is one of the primary forms of L-carnitine, along with propionyl-L-carnitine. Acetyl-L-carnitine is able to cross the blood-brain barrier more efficiently than L-carnitine. Therefore, acetyl-L-carnitine provides neuroprotective benefits, including antioxidant activity, improved mitochondrial energetics, stabilization of intracellular membranes, cholinergic neurotransmission activity, and enhancement of brain growth factors known to naturally decline with age.†