This means it must be obtained through the diet in adequate quantities to meet the body's needs.
Leucine is a member of the branched-chain amino acid family, along with valine and isoleucine.
The three branched-chain amino acids constitute approximately 70 percent of the amino acids in the body proteins. As such, their value in the formation and maintenance of structural and functional integrity in humans is unmeasured. It has recently been suggested leucine may have beneficial therapeutic effects on the prevention of protein wasting, as it occurs during starvation, semi-starvation, trauma, or recovery after surgery. It has also been recently suggested leucine has anabolic effects, thereby preventing muscle protein breakdown and stimulating muscle protein synthesis. Therapeutic use of leucine occurs at doses between 500 and 1,000mg per day.