Acetyl-L-carnitine is a combined form of the amino acid L-carnitine. It occurs naturally in the brain and has been studied as a possible treatment for Alzheimer's disease. Supplements of acetyl-L-carnitine may have a protective effect on the central nervous system and, like L-carnitine itself, may benefit the heart. (I don't recommend taking L-carnitine except as an adjunct to other treatments for serious heart conditions.)
Some preliminary research has suggested that acetyl-L-carnitine may help slow the progression of Alzheimer's disease, particularly among younger patients. There is also some evidence that this compound can enhance visual memory and attention in people with Down Syndrome, and clinical data indicates that it also may slow age-related mental decline that is not associated with Alzheimer's. However, the results of all of these studies must be considered preliminary - there is no hard evidence that supplements of acetyl-L-carnitine will reliably deliver the improvements noted. In general, I would urge you to be skeptical about extravagant advertising claims for any supplement.
That said, I checked with anti-aging and Alzheimer's disease expert Dharma Singh Khalsa, MD, about the potential benefits of acetyl-L-carnitine. Dr. Khalsa is president and medical director of the Alzheimer's Prevention Foundation International and author of the book "The Better Memory Kit" to be published later this year. He tells me that supplemental acetyl-L-carnitine can increase energy in the mitochondria, the power plants of all cells, and thereby helps generally boost physical and mental energy. He describes acetyl-L-carnitine as a superior antioxidant that promotes the production in cells of glutathione, perhaps our most potent free radical scavenger. If you decide to try it, Dr. Khalsa recommends taking 500 to 1,500 mg per day along with 100 mg of coenzyme Q10.
Andrew Weil, M.D.