Product Reviews
Acetyl-L-Carnitine Supplements Review

Reviewed and edited by Tod Cooperman, M.D. Tod Cooperman, M.D.
Initial Posting: 7/6/2012 Last Update 12/2/18
Acetyl-L-Carnitine Supplements Tested by

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(4/5/16): Two CL members reported recently purchasing one of the Approved products in this review and noticing a problem with some of the capsules. For more details, see the Update at the top of the full report.

What It Is:
Acetyl-L-carnitine is a particular form of carnitine, a non-essential amino acid that can be synthesized in the body from lysine and methionine and is found in red meats and dairy products. It is believed that acetyl-L-carnitine plays a role in production of acetylcholine, an important neurotransmitter.

What It Does:
Acetyl-L-carnitine is one of many dietary supplement ingredients that have been used to help prevent or treat memory disorders. Other ingredients tested and reviewed by include ginkgo, huperzine A, ginseng, niacinamide, and fish/marine oils. Additional clinical information about these and other ingredients, including phosphatidylserine, Bacopa monniera, and vinpocetine is found in the article "Enhancing Memory and Mental Function" in the Encyclopedia on this site.

Acetyl-L-carnitine may improve memory and cognition in older people with age-related memory problems. While early studies found evidence of modest benefit with acetyl-L-carnitine in Alzheimer's disease and other forms of dementia, more recent, large studies failed to find it effective (Hudson, Cochrane Database Syst Rev 2003). However, acetyl-L-carnitine may have benefit in mild cognitive impairment and early Alzheimer's disease (Montgomery, Int Clin Psychopharmacol, 2003).

Acetyl-L-carnitine seems to improve symptoms of diabetic neuropathy and neuropathy associated with antiretroviral drug therapy used by people with HIV infection. It also may reduce pain and improve mental health in people with fibromyalgia.

Taking acetyl-L-carnitine in combination with propionyl-L-carnitine seems to help symptoms of androgen decline in older men, improving sexual dysfunction, depression, and fatigue. It may also improve memory in chronic alcoholics and increase sperm motility in men with infertility. Acetyl-L-carnitine may be helpful in an inflammatory condition of the penis called Peyronie's disease, where it has been shown to reduce pain and slow progression of the disease (Biagiotti, BJU Int. 2001). Early research suggests that acetyl-L-carnitine might reduce hyperactivity in boys with fragile X syndrome.

Some studies with L-carnitine (not acetyl-L-carnitine) have evaluated its potential use in weight loss because L-carnitine is involved in the transport of fatty acids into the mitochondria of cells for use as fuel. However, a weight loss benefit has not been demonstrated. A study in which moderately obese women were given 2 grams daily of L-carnitine for eight weeks showed no effect on amounts of body fat or body weight (Villani, Int J Sport Nutr Excerc Metab 2000).

See the Encyclopedia on this website for more information about clinical studies with acetyl-L-carnitine.

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