Acetyl L-Carnitine Overview

Acetyl l-carnitine, abbreviated ALCAR, is derived from l-carnitine.

L-carnitine is a compound which is synthesized from two amino acids: methionine & lysine.

Acetyl l-carnitine is formed through a process known as acetylation, in which an acetyl group is added to a l-carnitine compound.

There are many benefits of acetyl l-carnitine & l-carnitine; probably the most well known are their antioxidant properties.

Acetyl l-carnitine supplements are often marketed for their antioxidant benefits and for other properties including as an aid to exercise and recovery. Carnitine based supplements may also benefit a number of conditions. Any side effects of acetyl l-carnitine are usually mild.

What Is Carnitine?

Carnitine is a compound synthesized in the body. Carnitine is required for metabolic energy to be generated; through a process in which fatty acids are converted into energy.

Carnitine is required to transport fatty acids to the mitochondria of cells. Mitochondria are often referred to as the powerhouse of the cell from where energy is produced.

Where Is Carnitine Produced & Stored?

Within the body, carnitine is synthesized mainly in the kidneys and liver; vitamin C is required for synthesis to occur.

Carnitine is stored in the brain, heart, skeletal muscles and sperm.

Acetyl L-Carnitine Structural Formula

The structural formula of acetyl l-carnitine is: C9 H17 NO4

Carnitine Structural Formula

The structural formula of carnitine is: C7 H15 NO3

What Are The Differences Between L-Carnitine & Acetyl L-Carnitine?

Acetyl l-carnitine (ALCAR) has an acetyl group which l-carnitine does not have.

The body can convert l-carnitine to acetyl l-carnitine and back again when it requires either of these compounds.

For example, when high energy demands are put on the body such as during intense exercise, l-carnitine and acetyl-CoA, an important compound used in metabolism, is converted to acetyl l-carnitine within the mitochondria. When acetyl l-carnitine reaches the outside of mitochondria, it is converted back to l-carnitine and acetyl-CoA.

As a supplement taken orally, acetyl l-carnitine has greater absorption, or bioavailability, compared to l-carnitine [6]. Bioavailability refers to the extent to which a compound enters the body and reaches the tissue where it's needed.

A further difference between these slightly different compounds is that unlike acetyl l-carnitine, l-carnitine does not enter cells unless there is a spike in insulin within the blood [7].

Also, acetyl l-carnitine passes more easily through the blood-brain barrier compared to l-carnitine where it is able to act as an antioxidant in the brain; another benefit of acetyl l-carnitine.

Sources Of Acetyl L-Carnitine

Natural sources of acetyl l-carnitine are through dietary supplements and foods derived from animals and plants. When l-carnitine is ingested, some of this is converted to acetyl l-carnitine [5].

Dietary Sources Of L-Carnitine

The diet can provide many sources of l-carnitine.

Highest concentrations come from red meats such as beef steak, ground beef and lamb. For example, 100g of beef steak contains approximately 95mg of carnitine, whilst 100g of ground beef contains 94mg.

Whilst containing less carnitine compared to red meats, dairy products including milk and cheese are also quite a rich source. For example, 100ml of milk contains 3.3mg of carnitine whilst 100g of cheese contains 3.7mg.

Each day approximately 20-200mg of carnitine is ingested by adults on a standard omnivorous diet, in which both animal and plant foods are eaten. In vegetarians, this daily intake may be much lower.