Acetylcarnitine
Encyclopedia
Acetyl-L-carnitine or ALCAR, is an acetylated form of L-carnitine
. It is a dietary supplement and naturally occurs in plants and animals.
derivative of L-carnitine
. 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 increases with administration of either ALCAR or L-carnitine. A portion of L-carnitine is converted to ALCAR after ingestion in humans.
. Both use the same mechanism for intestinal absorption that improves with sodium. One study shows ALCAR has a lower blood concentration in humans after ingestion possibly because ALCAR is hydrolyzed more in blood. This means it has less bioavailability unless it is entering cells (e.g., brain or muscle) more efficiently from the blood than L-carnitine. L-carnitine is known to not absorb into cells unless there is an insulin spike such as from a carbohydrate load.
and get to the brain blood circulation, where it acts as a powerful antioxidant
, which helps in prevention of the brain cells' deterioration. Its supplementation has been shown to be neuroprotective in instances of cerebral ischemia in rats and may be useful in treating peripheral nerve injury.
It may have some neuroprotective benefit in the treatment of Parkinson's disease
, but further research is required. ALCAR is also known to increase sperm motility
, which pertains to the ability of sperm to move vigorously. Since motility is among the most important factors that help in the determination of sperm’s fertilization capability, acetyl-L-carnitine can help sperm cells move more actively, which consequently leads to the improved male fertility. Research into the compound's safety and efficacy in humans is required.
ALCAR has been shown to be more effective than tamoxifen
in improving the curvature and reducing the pain and plaque sizes for men who sought treatment for their Peyronie's disease
early and having low curvature deformities. ALCAR has also been shown to improve insulin response and is proved to have a positive effect on various muscle diseases as well as heart conditions.
Carnitine
Carnitine is a quaternary ammonium compound biosynthesized from the amino acids lysine and methionine. In living cells, it is required for the transport of fatty acids from the cytosol into the mitochondria during the breakdown of lipids for the generation of metabolic energy. It is widely...
. It is a dietary supplement and naturally occurs in plants and animals.
Biochemical Production and Action
ALCAR is an acetylatedAcetylation
Acetylation describes a reaction that introduces an acetyl functional group into a chemical compound...
derivative of L-carnitine
Carnitine
Carnitine is a quaternary ammonium compound biosynthesized from the amino acids lysine and methionine. In living cells, it is required for the transport of fatty acids from the cytosol into the mitochondria during the breakdown of lipids for the generation of metabolic energy. It is widely...
. During strenuous exercise, a large portion of L-carnitine and unused acetyl-CoA
Acetyl-CoA
Acetyl coenzyme A or acetyl-CoA is an important molecule in metabolism, used in many biochemical reactions. Its main function is to convey the carbon atoms within the acetyl group to the citric acid cycle to be oxidized for energy production. In chemical structure, acetyl-CoA is the thioester...
are converted to ALCAR and CoA inside mitochondria by carnitine O-acetyltransferase
Carnitine O-acetyltransferase
In enzymology, a carnitine O-acetyltransferase is an enzyme that catalyzes the chemical reactionThus, the two substrates of this enzyme are acetyl-CoA and carnitine, whereas its two products are CoA and O-acetylcarnitine....
. 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 increases with administration of either ALCAR or L-carnitine. A portion of L-carnitine is converted to ALCAR after ingestion in humans.
Absorption Compared to L-carnitine
It has been claimed ALCAR is superior to L-carnitine in terms of bioavailabilityBioavailability
In pharmacology, bioavailability is a subcategory of absorption and is used to describe the fraction of an administered dose of unchanged drug that reaches the systemic circulation, one of the principal pharmacokinetic properties of drugs. By definition, when a medication is administered...
. Both use the same mechanism for intestinal absorption that improves with sodium. One study shows ALCAR has a lower blood concentration in humans after ingestion possibly because ALCAR is hydrolyzed more in blood. This means it has less bioavailability unless it is entering cells (e.g., brain or muscle) more efficiently from the blood than L-carnitine. L-carnitine is known to not absorb into cells unless there is an insulin spike such as from a carbohydrate load.
Health Claims
ALCAR has the ability to cross the blood-brain barrierBlood-brain barrier
The blood–brain barrier is a separation of circulating blood and the brain extracellular fluid in the central nervous system . It occurs along all capillaries and consists of tight junctions around the capillaries that do not exist in normal circulation. Endothelial cells restrict the diffusion...
and get to the brain blood circulation, where it acts as a powerful antioxidant
Antioxidant
An antioxidant is a molecule capable of inhibiting the oxidation of other molecules. Oxidation is a chemical reaction that transfers electrons or hydrogen from a substance to an oxidizing agent. Oxidation reactions can produce free radicals. In turn, these radicals can start chain reactions. When...
, which helps in prevention of the brain cells' deterioration. Its supplementation has been shown to be neuroprotective in instances of cerebral ischemia in rats and may be useful in treating peripheral nerve injury.
It may have some neuroprotective benefit in the treatment of Parkinson's disease
Parkinson's disease
Parkinson's disease is a degenerative disorder of the central nervous system...
, but further research is required. ALCAR is also known to increase sperm motility
Sperm motility
Sperm motility describes the ability of sperm to move properly towards an egg. This can also be thought of as the 'quality' of the sperm, which is a factor in successful pregnancies, as opposed to the 'quantity'. Sperm which do not properly 'swim', will not reach the egg in order to fertilize it...
, which pertains to the ability of sperm to move vigorously. Since motility is among the most important factors that help in the determination of sperm’s fertilization capability, acetyl-L-carnitine can help sperm cells move more actively, which consequently leads to the improved male fertility. Research into the compound's safety and efficacy in humans is required.
ALCAR has been shown to be more effective than tamoxifen
Tamoxifen
Tamoxifen is an antagonist of the estrogen receptor in breast tissue via its active metabolite, hydroxytamoxifen. In other tissues such as the endometrium, it behaves as an agonist, hence tamoxifen may be characterized as a mixed agonist/antagonist...
in improving the curvature and reducing the pain and plaque sizes for men who sought treatment for their Peyronie's disease
Peyronie's disease
Peyronie's Disease Peyronie's Disease Peyronie's Disease (also known as "Induratio penis plastica", or more recently Chronic Inflammation of the Tunica Albuginea (CITA), is a connective tissue disorder involving the growth of fibrous plaques in the soft tissue of the penis affecting up to 10% of men...
early and having low curvature deformities. ALCAR has also been shown to improve insulin response and is proved to have a positive effect on various muscle diseases as well as heart conditions.
Other reviews
- Carnitine (L-carnitine), University of Maryland Medical Center