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It is an essential amino acid and is not synthesized in the body. Chemically it is alpha-aminoisocaproic acid. The microorganisms may synthesize this amino acid. In microorganisms it is synthesized from alpha-ketoisovaleric aicd and acetyl CoA.
Leucine can be broken down into simpler compounds by the enzymes of the body. Leucine contributes to the structure of proteins into which it has been incorporated by the tendency of its side chain to participate in hydrophobic interactions. Leucine was isolated from cheese in an impure form in 1819 and from muscle and wool in the crystalline state in 1820. It was named after the Greek word leukos [white], evidently because at that time the purification of a substance from nature to a white, crystalline state was considered noteworthy. The structure of leucine was established by laboratory synthesis in 1891.
Bodybuilders and other athletes to promote muscle recovery, although it has not produced significant changes in body composition, use supplements and protein powders that contain leucine extensively.
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Sources of protein
It is found in protein foods, as well as brown rice, beans, nuts and whole wheat.
- Cottage cheese (dry) 4,500 mg/cup
- Cottage cheese 3,294 mg/cup
- Fish & other sea foods 1,000-10,000 mg/lb
- Meats 2,000 -8,500 mg/lb
- Poultry 3,500-8,500 mg/lb
- Peanuts, roasted w skin 4,500 mg/cup
- Sesame seeds 3,500 mg/cup
- Dry, whole lentils 3,500 mg/cup
Benefits of leucine
Leucine helps with the regulation of blood-sugar levels, the growth and repair of muscle tissue (such as bones, skin and muscles), growth hormone production, wound healing as well as energy regulation. Insulin deficiency is known to result in poor utilization of leucine; therefore, individuals who suffer from glucose intolerance may require higher levels of leucine intake.
It can assist to prevent the breakdown of muscle proteins that sometimes occur after trauma or severe stress.
It may also be beneficial for individuals with phenylketonuria - a condition in which the body cannot metabolize the amino acid phenylalanine
Leucine has anabolic effects, thereby preventing muscle protein breakdown and stimulating muscle protein synthesis.
Leucine, with the help of other two amino acids, isoleucine and valine, helps in treating and in reversing some cases of hepatic encephalopathy, a form of liver damage in alcoholics. They also help to prevent muscle wasting in this disease and through their actions on brain neurotransmitters, help prevent some adverse neurological effects of chronic liver disease.
Leucine appears to be the most important BCAA (Branched chain amino acid) for athletes, as it can affect various anabolic hormones, and have an effect on preventing protein degradation.
Deficiency symptoms of leucine
Deficiency of this nutrient is rare, as it is present in all the protein foods vegetarians without adequate protein sources may suffer from a deficiency.
Hypoglycemia symptoms may appear if the diet is deficient and may include dizziness, fatigue, headaches, irritability etc.
An inborn error in leucine metabolism can lead to "maple syrup urine disease". This is generally seen in infants and result in retardation. This is a very rare condition, however, and is not a general concern as it relates to leucine supplementation.
Symptoms of high intake
No evidence of toxicity has been known.
A high intake of leucine could contribute to pellagra as well as increase the amount of ammonia present in the body.
Daily requirement
The daily dosage of leucine is about 16 mg per kilogram of body weight per day - which would translate to about 1120 mg for a 70 kg male.
Other facts
This is one of the most important amino acids for hard training body builders. Leucine and the other branched chain amino acids (BCAAs), isoleucine, and valine, escape liver metabolism and can directly and significantly influence muscle-protein metabolism. Dietary leucine serves as a substrate for muscle metabolism during periods of cellular energy depletion, there by sparing critical contractile and enzyme muscle protein from degradation to supply leucine requirements.
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