Acetyl-L-carnitine is a naturally occurring dietary supplement that converts in the body to L-carnitine and acetyl-coenzyme A (acetyl-CoA). The kidney and liver also produce L-carnitine from the amino acids, lysine, and methionine. The primary function for L-carnitine is the transport of fatty acids across cell membranes and into the energy factories of the cells, the mitochondrion, which then break down the fatty acids to produce energy for cell functions. Without L-carnitine, the fatty acids remain outside the cells, unavailable for conversion into energy. Supplementation with acetyl-L-carnitine increases the body’s supply of L-carnitine, facilitating the burning of fat by the body.
The body tissues that primarily use L-carnitine are those tissues with high requirements for energy, such as skeletal muscles and the muscles of the heart. Deficiencies in L-carnitine may occur due to dietary malabsorption or vegetarian diets. Although the body can produce small quantities of L-carnitine, in some circumstances, such as bodybuilding or restrictive dieting, the demand for L-carnitine may outstrip the body’s ability to supply it. Symptoms of L-carnitine deficiency include muscle weakness, cramping, irregular heartbeat, and fatigue. These symptoms may point to a need for acetyl-L-carnitine supplementation.
Health experts attribute several benefits to acetyl-L-carnitine supplementation. In addition to acceleration of fat burning, Acetyl-L-carnitine crosses the blood-brain barrier, where it has a potent protective, antioxidant effect. The supplement may protect the brain from blood flow interruptions, such as with a stroke, and prevent damage from neurodegenerative diseases, such as Parkinson’s disease. It may also enhance the motility of sperm, helping with some forms of male infertility, and strengthen the body’s response to insulin, lowering the blood sugar. Based on anecdotal reports, acetyl-L-carnitine may improve mental agility and ward off depression.
Although acetyl-L-carnitine is relatively safe, a few side effects have been documented for this supplement. If taken in large quantities, it may cause diarrhea. The body temperature could rise, producing fever in some cases. In addition, rises in heart rate and blood pressure may occur. These side effects are transitory, resolving completely if the supplement is discontinued. Patients with a medical history of high blood pressure or heart disease must take these supplements with caution and under a doctor’s supervision.
Natural dietary sources of L-carnitine include dairy products, chicken and red meat. For vegetarians, some L-carnitine may be derived from asparagus, peanut butter, and wheat. The recommended daily requirement for acetyl-L-carnitine is approximately two grams per day. Most of the commercially available supplements are 250 to 500 milligrams, with a daily dose of four to eight tablets per day.