Leucine is an essential amino acid and one of the branched chain amino acids.  These work together to protect muscle and act as fuel.  Leucine plus other dietary proteins fosters muscle growth even without the other two branched chain amino acids.  They promote the healing of bones, skin, and muscle tissue, and are recommended for those recovering from surgery.  Leucine also lowers elevated blood sugar levels and aids in increasing growth hormone production.

Natural sources of leucine include brown rice, beans, meat, nuts, soy flour, and whole wheat.  Supplemental L-leucine must be taken in balance with L-isoleucine and L-valine and it should be taken in moderation, or symptoms of hypoglycemia may result.  An excessively high intake of leucine may also contribute to pellagra, and may increase the amount of ammonia present in the body.