The Benefits & Side Effects Acetyl-L-Carnitine

Carnitine is found naturally in red meat and dairy products, as well as some plant foods. Its basic function in the body is to assist the transport of fat into the mitochondria--the mini furnaces inside your cells--where it is converted into energy. According to the University of Maryland Medical Center, the heart, muscles, brain and sperm rely on L-carnitine for energy. As of 2010, acetyl-L-carnitine is gaining popularity as a nutritional supplement.

Cognitive Function

• Because carnitine is stored in the brain tissue and used by the brain to convert fat into energy, some people believe that taking acetyl-L-carnitine orally will enhance brain function. Study results are promising. Patients with mild cognitive impairment and mild Alzheimer's disease experienced improvement in their cognitive function when they took between 1.5 and 3.0 grams of acetyl-L-carnitine daily, according to a 2003 study published in the journal International Clinical Psychopharmacology. In 2010, scientists at the Center for Cell Neurobiology and Neurodegeneration Research at the University of Massachusetts gave the supplement to healthy adults without dementia as part of a nutritional formula. According to their paper in the Journal of Nutrition, Health & Aging, these adults showed improved mental performance on tests.

Vitality

• Acetyl-L-carnitine's known role in converting fat to energy has generated much interest in its use as a weight loss tool. L-carnitine was found to reduce body fat and increase muscle mass in a study of men and women over the age of 100, "L-Carnitine Treatment Reduces Severity of Physical and Mental Fatigue and Increases Cognitive Functions in Centenarians." Although such studies generate a lot of interest in the potential of acetyl-L-carnitine as an athletic supplement, most investigations into this topic have not shown definite benefits for healthy people, according to the Linus Pauling Institute at Oregon State University.

Heart Health

• Acetyl-L-carnitine has a protective function in the heart muscle as well as in the brain and other muscles of the body. According to a 2006 study published in The FASEB Journal titled, "Reversal of Mitochondrial Defects Before Ischemia Protects the Aged Heart," experiments on animals demonstrate that the heart muscle is better able to endure the loss of oxygen due to blood clots when acetyl-L-carnitine is given before a cardiac event.

Sperm Motility

• Another area in which the body stores L-carnitine is the epididymis in men, the tube that houses sperm as they mature. In the epididymis, sperm acquire the ability to swim and to fertilize eggs. Some scientists have suggested that if a man is deficient in L-carnitine, his sperm will lack motility. Several studies, including a 2007 trial published in the Asia Pacific Journal of Clinical Nutrition on the effects of nutritional carnitine, indicate that taking acetyl-L-carnitine as a supplement greatly improves sperm motility and enhances male fertility.

Side Effects

• The Physicians' Desktop Reference suggests that people taking more than 500 mg of acetyl-l-carnitine daily sometimes develop digestive upset, insomnia and irritability. The Linus Pauling Institute at Oregon State University notes that acetyl-L-carnitine has no reported toxic effects. Avoid any supplements that contain D-carnitine, however. This form of carnitine is not bioactive, but it does block absorption of the beneficial L-carnitine, and can leave you feeling weak or fatigued. Talk to your doctor if you suffer from hypertension, diabetes, kidney disease, vascular disease, cirrhosis, or if you have any doubts about taking acetyl-L-carnitine.