Some research suggests that acetyl-L-carnitine can improve fatigue associated with multiple sclerosis (MS), although more study is needed.
Acetyl-L-carnitine is a form of L-carnitine, an amino acid that is found in nearly all cells of the body. L-carnitine plays a critical role in the production of energy from long-chain fatty acids. In addition, it increases the activity of certain nerve cells in the central nervous system.
Fatigue is a common symptom in people with multiple sclerosis. The cause isn't well understood. A study published in 2006 evaluated the benefit of supplementation with L-carnitine in people with MS-related fatigue who had low blood levels of L-carnitine. Study participants were given 3 to 6 grams of oral L-carnitine daily. Researchers reported a decrease in fatigue intensity in 65 percent of participants treated with immunosuppressive drugs, especially in those treated with cyclophosphamide and interferon beta. Another study published in 2004 showed that acetyl-L-carnitine seemed to improve fatigue in people with MS better than amantadine, a drug commonly used to treat MS-related fatigue.
However, problems with the design of these studies make it unclear whether acetyl-L-carnitine is truly effective at reducing MS-related fatigue. A recent systematic review published in 2012 concluded that there is still insufficient evidence that carnitine offers a therapeutic advantage over placebo or other medications. An ongoing larger scale randomized, placebo-controlled clinical trial expected to be completed in 2013 may answer some of these questions.
Although acetyl-L-carnitine generally has few or mild side effects, it can interfere with anticoagulants and other medications. So talk to your doctor before starting acetyl-L-carnitine or any dietary supplement.