Leucine is an essential amino acids which cannot be synthesized by the body but must always be acquired from dietary sources. Leucine is available in good concentrations in meat and dairy products, and to a lesser degree in wheat germ, brown rice, soybeans, almonds, cashews and brazil nuts, chickpeas, lentils and corn. Leucine stimulates protein synthesis in muscles, and is essential for growth. Leucine also promotes the healing of bones, skin and muscle tissue.
Leucine, and the other branched-chain amino acids (BCAAs), Isoleucine and Valine, are frequently deficient in the elderly, and increased body requirements can occur after trauma or surgery. These branched-chain amino acids may prevent muscle wasting in these conditions, but no studies have been done to determine if extra intake will help in muscle building in healthy individuals. Because leucine cannot be made by the body from other sources, it IS important to maintain adequate amounts in the diet.
Leucine, in conjunction with two other amino acids, isoleucine and valine, appear to be quite helpful in treating and in some cases even reversing hepatic encephalopathy, a form of liver damage in alcoholics. They also help curb muscle wasting in this disease and through their actions on brain neurotransmitters, help prevent some adverse neurological effects of chronic liver disease.
A recent study shows that leucine, isoleucine and valine may be helpful in ALS, known as Lou Gehrig disease. This is a potentially fatal disease for which no other effective treatment has been found. This pilot study involved nine ALS patients, of whom eight benefitted from supplementation with these amino acids, top the extent that over the one year period of the study, they retained their muscle strength and their ability to walk. Five of the nine control subjects, who received placebos, lost their ability to walk over this period.
A study reported in the British Journal of Nutrition found that a dietary excess of leucine may be a precipitating factor in causing pellagra. This effect was only apparent when the diet also provided less than adequate amounts of nicotinamide. The right handed, or D form of leucine, has been shown to have a similar effect to that of d-phenylalanine in retarding the breakdown of the natural pain killers of the body, the endorphins and enkephalins.