ALCAR
Meaning of ALCAR: A supplement form of carnitine tested against chemotherapy nerve damage, where the largest trial found the nerve injury worse rather than better.
Definition of ALCAR
ALCAR is short for acetyl-L-carnitine, a form of carnitine carrying an extra acetyl group that helps it cross into the brain. Carnitine itself ferries long-chain fats into the mitochondria, the compartments inside cells where fuel is burned for energy. ALCAR is sold as a dietary supplement and has been studied in nerve damage, memory complaints and fatigue without becoming an approved treatment for any of them.
Where does carnitine come from?
Most of it comes from food, chiefly red meat and dairy, which is reflected in the name: the root is the Latin word for flesh. The remainder the body builds for itself from two amino acids, and it does so in the liver, the kidneys and the brain. Muscle, which holds the great majority of the body's stock, cannot make any and takes up what it needs through a dedicated transporter. Reference entries that describe carnitine as being made in muscle confuse where it is stored with where it is manufactured.
What happened in the neuropathy trials?
Nerve damage in the hands and feet limits how much taxane chemotherapy can be given, so a protective agent would be valuable, and laboratory work suggested this compound might qualify. A randomized comparison against placebo, run alongside treatment, did not protect anyone. At later assessment the group that had received it reported more numbness, tingling and pain than the placebo group, not less. That result reverses the older description of a substance under study for preventing chemotherapy damage, and it is the reason the idea was not carried forward.
How do the forms differ?
| Form | Distinguishing feature | Sold or prescribed for |
|---|---|---|
| L-carnitine | The natural form the body uses | Genuine deficiency; general supplement |
| Acetyl-L-carnitine | Carries an acetyl group, enters the brain more easily | Memory and nerve complaints |
| Propionyl-L-carnitine | Carries a propionyl group | Circulation complaints |
| D-carnitine | Mirror image, unusable | Nothing; it obstructs the natural form |
Carnitine does have an established medical role, and it lies well away from the supplement shelf. A rare inherited fault in the transporter, and depletion caused by dialysis or by certain medicines, produce genuine deficiency with muscle weakness and heart involvement, treated with a prescribed preparation.
Also known as
Used in a sentence
The supplement list included ALCAR taken daily.
Good to know
Carnitine is manufactured in the liver, kidneys and brain rather than in muscle, although muscle holds most of the body's supply, and a randomized trial of acetyl-L-carnitine given with taxane chemotherapy recorded more nerve symptoms in the treated group than in the placebo group.