What Are the Functions of Leucine?

Leucine is an essential amino acid, one that human bodies do not manufacture naturally. As such, it is commonly taken in supplements or in leucine-rich foods like meat, dairy products, nuts and soy. In the body, leucine is used primarily in muscle tissue, the liver and body fat (adipose tissue). Bodybuilders in particular seek out sources of leucine to enhance muscle growth.

Providing Energy

• The normal functions of muscle tissue break down and consume leucine, a source of energy. Humans normally receive only a small amount of leucine through daily food consumption, so many bodybuilders take dietary supplements to increase the amount of leucine the muscles have at their disposal.

Preserving Mass

• In addition to providing energy to the muscles, leucine helps to preserve existing muscle mass and to stimulate the growth of new muscle cells. Muscles rich in leucine are less susceptible to damage and require less time to recover from injury. Many bodybuilders believe leucine encourages muscles to grow back with added mass. Older individuals should also consider leucine supplements as a proactive approach to preventing muscle wasting.

Controlling Appetite

• New research is showing leucine may have some function in helping to regulate appetite. Amino acids, including leucine, have a role in how the brain regulates metabolism and the feeling of hunger. When leucine was applied to this area of the brain in rats, metabolic functions were better regulated, and the animals consumed less food. While research is still preliminary, there may be some future application for humans.