Leucine

Leucine is an amino acid that cannot be manufactured in the body. It must be obtained through foods. Leucine is considered an essential branched chained amino acid (BCAA). This means it plays significant roles in the maintenance and repair of muscles and in preventing the breakdown of muscle protein during exercise. Foods rich in leucine include egg whites, soy protein isolate and brown rice as well nuts and supplements with leucine.

Function

Leucine supplements and protein powders with leucine are popular among athletes and bodybuilders. These products prevent muscle breakdown during athletic performances and help with muscle recovery and other functions. Along with leucine are two other essential amino acids called L-isoleucine and L-valine. These amino acids must also be obtained from foods, and they promote lean muscle growth and muscle recovery as well as provide other benefits.

Significance

Leucine is the most significant of the amino acids, and it is the strongest. It also is known as the limiting nutrient, because enough leucine in proportion to the other amino acids is necessary for the body to obtain the benefits from your dietary intake.

Benefits

Leucine serves many purposes in the body, especially for athletes. Leucine increases the energy level of the body and keeps the mind clear during the stress of athletic performance. It maintains the nitrogen balance, which relates to the amount of nitrogen taken in the body to the amount excreted. Leucine stores glycogen in the muscle tissues, which is the source of power needed to move the muscles.

Leucine Deficiency

Leucine cannot be made in the body, but it is easily available from foods. Therefore a leucine deficiency is rare. A leucine deficiency is characterized by feelings of fatigue, headaches, dizziness and cramps. In addition, there is muscle weakness, irritability, frequent infections, slow wound healing and feelings of depression.

Food Rich in Leucine

The top foods with the highest amounts of leucine, according to the Nutrition Data website, are:
Egg whites, raw and fresh, 4233 mg
Soy protein isolate, potassium, crude protein basis, 4226 mg
Soy protein isolate, potassium type, 4162 mg
Soy protein isolate, 4013 mg
Seaweed, spirulina- raw, 3915 mg
Game meat (moose) cooked, roasted, 3844 mg
Game meat, (moose) raw, 3838 mg
Egg white, dried flakes, glucose-reduced 3816 mg
Egg white, dried powder, glucose-reduced 3815 mg
There are many other foods with leucine such as cheese, fish, chicken and turkey, lamb and veal.