acetyl-L-carnitine
Meaning of acetyl-L-carnitine: A form of carnitine that reaches the brain, sold as a supplement and studied mostly for nerve damage and memory.
Definition of acetyl-L-carnitine
Acetyl-L-carnitine is a form of carnitine, a compound the body makes from two amino acids and also absorbs from meat and dairy foods. Carnitine ferries fatty acids into the part of the cell that burns them for energy. Adding an acetyl group produces a version that crosses into the brain more readily, which is why this form is the one usually studied for nerve and memory effects.
What does carnitine do in the body?
Fat is burned inside mitochondria, the compartments that generate a cell's energy, but long fatty acid chains cannot cross the mitochondrial membrane unaided. Carnitine attaches to them and carries them through, then returns for the next load. Muscle and heart tissue, which rely heavily on fat as fuel, hold the largest stores. The body manufactures its own supply in the liver and kidney from lysine and methionine, so a deficiency in an otherwise healthy person on a mixed diet is unusual. Genuine deficiency states exist and are inherited, or arise in kidney failure and with certain medicines.
How does the acetylated form differ?
| Carnitine | Acetylated form | |
|---|---|---|
| Entry into the brain | Limited | Crosses more readily |
| Main study focus | Muscle, heart, deficiency states | Nerve pain, memory, mood |
| Extra chemical role | Supplies acetyl groups used in other reactions |
What has it been studied for?
Nerve damage is the main theme. Trials have looked at painful nerve damage in diabetes, at nerve damage caused by HIV medicines, and at age related memory decline, with results that are mixed and mostly from small studies. Its use to prevent nerve damage from chemotherapy deserves particular note, because a trial designed to test that idea found more nerve damage in the group receiving it rather than less. That finding is a reminder that a plausible mechanism does not guarantee benefit, and it has discouraged that particular application.
How is it regulated?
In most countries it is sold as a dietary supplement rather than licensed as a medicine, so content and purity are not verified to pharmaceutical standards. Reported effects are usually mild and involve stomach upset, restlessness or a fishy body odor at higher intakes. Prescription carnitine preparations do exist, but they are used for diagnosed deficiency rather than for the purposes attached to the supplement.
Also known as
Used in a sentence
The supplement history included acetyl-L-carnitine taken for peripheral neuropathy.
Good to know
A trial testing this compound for prevention of chemotherapy related nerve damage found more nerve damage in the treated group, so a plausible mechanism is not evidence of benefit.