Although much more study is needed, and several existing studies have been significantly flawed, acetyl-L-carnitine does seem to have promise in enhancing quality of life for people with cognitive problems and nerve damage, especially when those problems are the side effects of disease or other drug therapies [source: UMHS].
For example, some AIDS and HIV treatments cause muscular wasting and impair nervous function. There's a possibility that acetyl-L-carnitine could restore some of that function.
Likewise, alcohol abuse can gradually impair nervous function, partly because the liver loses its ability to process fat. In severe cases, it leads to a condition called hepatic encephalopathy. Acetyl-L-carnitine might help restore the balance. However, severe, long-term alcoholism has many cognitive effects that go beyond fat metabolism.
In a study, the drug also seemed to help a group of seniors with mild Alzheimer's disease, the progressive (and irreversible) neurological disorder that gradually destroys a person's memory, independence, motor functions and sense of self. Some patients who took supplements of acetyl-L-carnitine had reduced symptoms of dementia [source: NAT]. Later studies, though, were unable to duplicate this success [source: Hudson].
Another group of seniors with mild depression saw significant improvement following regular acetyl-L-carnitine supplements [source: NAT]. Some cases of depression are related to chemical imbalances in the brain and nervous system, so it's hypothesized that acetyl-L-carnitine would treat depression by improving the overall chemical function of the nervous system.
Of course, happy senior citizens and recovering alcoholics are not nearly as alluring as the image of you with bodybuilder muscles and increased sexual function, so those tend to be the aspects of acetyl-L-carnitine that the pill industry touts. Ironically, these are the claims with the least scientific evidence to back them up [source: UMMC]. Acetyl-L-carnitine may aid in the treatment of Peyronie's disease, which can affect male sexual function [source: NAT]. But it's probably not going to become the new Viagra any time soon.
What are the risks of taking acetyl-L carnitine? Read on.