A Comparison Of L-carnitine & Acetyl L-carnitine

Carnitine is required by the body to transport fat into cells for use as an energy source. Carnitine is produced by the liver, kidney and brain and is stored in skeletal muscle, the heart and brain. Healthy individuals can produce the carnitine needed for normal body function. However, supplementation has been found effective as a treatment for individuals with heart disease, vascular disease, neuropathy and memory impairment. Although often suggested as a supplement to improve exercise performance and weight loss, there is no evidence that it is effective. Consult your physician before adding any supplement to your diet. Carnitine supplements are available in several forms, including L-carnitine and acetyl-L-carnitine.

Structure

L-carnitine and acetyl-L-carnitine have identical chemical core structures. The difference between the two is the addition of an acetic acid bound by an ester linkage to the core in the latter. According to Dr. Benjamin Treadwell, this additional chemical component makes a difference in the way the two molecules behave in your body. A study published in 2004 in the Annals of the New York Academy of Science comparing the two suggested that acetyl-L-carnitine may be a better dietary supplement due to the difference in structure.

Absorption and Bioavailability

While L-carnitine is synthesized by the body, supplementation may be suggested if you have heart disease, Alzheimer's or HIV infection. Absorption and bioavailablity are important characteristics when choosing supplements to ensure the nutrient can be used by the body. The bioavailability of L-carnitine supplements is thought to be low, around 14 to 18 percent, according to the Linus Pauling Institute. Less is known about the bioavailability of acetyl-L-carnitine, but it is believed to be higher.

Functions

Both L-carnitine and acetyl-L-carnitine are equally effective in transporting fat into cells and increasing energy levels in older rats. However, acetyl-L-carnitine has been found to be more effective with respect to protecting the brain and central nervous system in animal studies. Acetyl-L-carnitine is believed to more readily cross the blood-brain barrier, which is in place to separate the brain from your general circulatory system, according to the University of Maryland Medical Center.

Considerations

Carnitine supplements should be used only under the advice of your physician. Doses usually range between 1 to 3 g, depending on the condition being treated. Side effects are usually mild, including gastrointestinal issues, body odor and rash. Supplements can react with medications, so be sure to speak with your health care provider.