Acetyl L-carnitine is an amino acid (a building block for proteins) that is naturally produced in the body. It helps the body produce energy.
Acetyl L-carnitine is used for a variety of mental disorders including Alzheimer’s disease, age-related memory loss, late-life depression, thinking problems related to alcoholism, and thinking problems related to Lyme disease. It is also used for Down syndrome, poor circulation in the brain, cataracts, nerve pain due to diabetes, nerve pain due to drugs used in the treatment of AIDS, and facial paralysis.
Some men use acetyl L-carnitine for infertility, symptoms of “male menopause” (low testosterone levels due to aging), and a disease of the penis called Peyronie’s disease.
Carnitine's primary job is in the regulation of cellular metabolism, and it closely interacts with coenzyme A in a variety of reactions. acetyl L-carnitine is also a potent antioxidant especially in combination with ALA and there is evidence that it increases exercise performance for this reason. A Russian study found that both L-carnitine and acetyl L-carnitine increased running speed and endurance in trained animals, and that the increase was proportional to their antioxidative activity. Another strong antioxidant is melatonin, and acetyl L-carnitine has also been shown to increase melatonin levels.
Supports cognitive function acetyl L-carnitine plays a strong role in the brain in many ways, and has beneficial effects. Studies in aged rodents show markedly improved memory and learning capacities, while studies in younger rodents show a variety of promising effects as well.
acetyl-L-carnitine supplementation is also accompanied by many positive structural changes in the brain in both the young and the old. It stimulates nerve growth factor (NGF) binding , and rodent studies indicate significantly more regenerative elements and reduced degenerative elements.
A study was done on humans, Metabolism. 2004 Aug;53(8 :1002-6. Twelve volunteers took 3grams of carnitine for 10 days on a regular diet. l-carnitine led to a dramatic increase in fat oxidation( Fat burning) while maintaining muscle (no decrease in protein catabolism). Another study was done on elderly men and they had a reduction in bodyfat, increased muscle and lower blood lip levels.
Acetyl L-carnitine helps shuttle free fatty acids into the mitochondria where they are burned off for energy. This is important because normally it is hard for the fatty acids to enter the mitochondria. This ultimately means more fat and less carbohydrates and protein, will be burned for energy in the mitochondria.
Carnitine might be a good addition to standard therapy for angina. In one controlled study, 200 individuals with angina (the exercise-induced variety) took either 2 g daily of L-Carnitine or were left untreated. All the study participants continued to take their usual medication for angina. Those taking Carnitine showed improvement in several measures of heart function, including a significantly greater ability to exercise without chest pain.
People with advanced hardening of the arteries, or atherosclerosis, often have difficulty walking due to lack of blood flow to the legs. Pain may develop after walking less than half a block. Although Carnitine does not increase blood flow, it appears to improve the muscle's ability to function under difficult circumstances. A 12-month double-blind placebo-controlled trial of 485 patients with intermittent claudication evaluated the potential benefits of Propionyl-L-Carnitine. Participants with relatively severe disease showed a 44% improvement in walking distance as compared to placebo. However, no improvement was seen in those with mild disease. Another double-blind study followed 245 people and also found benefit.
Several small studies have found that Carnitine, often in the form of propionyl-L-carnitine, can improve symptoms of congestive heart failure. In one trial, benefits were maintained for 60 days after treatment with Carnitine was stopped.
Carnitine may help reduce death rate after a heart attack. In a 12-month placebo-controlled study, 160 individuals who had experienced a heart attack received 4 g of L-Carnitine daily or placebo, in addition to other conventional medication. The mortality rate in the treated group was significantly lower than in the placebo group, 1.2% versus 12.5%, respectively. There were also improvements in heart rate, blood pressure, angina (chest pain), and blood lipids
A double-blind study of 60 seniors with mild depression found that treatment with 3 g of Carnitine daily over a 2-month period significantly improved symptoms as compared to placebo. Positive results were seen in another study as well.
The typical dosage for carnitine is 1-4 g/day. A study on the pharmacokinetics of oral L-carnitine in human subjects found no differences in plasma carnitine after 2 g vs. 6 g, indicating that 2 g is already more than the saturable dose. The half-life of the 2 gram dose was 6.5 hours, and this would imply that the ideal dosing schedule would be 1-2 grams 2-3 times daily, although many studies indicate beneficial effects with only 0.5-1.5 grams daily.