Leucine

Some important facts about this amino:
Leucine is the most common amino acid in proteins. Along with its isomer isoleucine, leucine is also one of the largest aliphatic amino acids. The side chain contains four fully protonated carbons arranged in an "Y" shape (in contrast to the "L" shape of leucine) that is both bulky and very hydrophobic, and this often relegates leucine to the hydrophobic core of a protein fold.
Leucine is isomeric with isoleucine. Nutritionally, in humans, leucine is an essential amino acid.Leucine is the most common amino acid found in proteins, and is essential for optimal growth in infancy and childhood and for nitrogen equilibrium in adults.

Use of leucine:
Leucine helps with the
1. Because it is so easily converted to glucose, leucine helps to regulate blood sugar;
2. The growth and repair of muscle tissue (such as bones, skin and muscles),
3. It also increases production of growth hormones, and helps burn visceral fat, which is located in the deepest layers of the body and the least responsive to dieting and exercise.
4. It can assist to prevent the breakdown of muscle proteins that sometimes occur after trauma or severe stress.
5. It may also be beneficial for individuals with phenylketonuria - a condition in which the body cannot metabolize the amino acid phenylalanine
6. It has recently been suggested that leucine may have beneficial therapeutic effects on the prevention of protein wasting, as it occurs during starvation, semi-starvation, trauma, or recovery after surgery.

Leucine, isoleucine, and valine are branched-chain amino acids (BCAAs), and all three of them help promote muscle recovery after exercise. Leucine is the most effective BCAA for preventing muscle loss because it breaks down and is converted to glucose more quickly than isoleucine and valine. Increased glucose supplies prevent the body's cannibalization of muscle for energy during intense workouts, so it is no surprise that this amino acid supplement is popular among professional body builders.

1. Leucine also promotes the healing of bones, skin, and muscle tissue after traumatic injury, and is often recommended for those recovering from surgery. Leucine is an essential amino acid, which means that it cannot be manufactured in the body and must be obtained through dietary sources. People that exercise a lot, have a low-protein diet, or are seriously trying to build muscle mass should consider leucine supplementation.
2. Leucine is also available in stand-alone supplemental form, but should always be taken together with the other two branched-chain amino acids, isoleucine and valine. The ideal balance is 2 milligrams of leucine and valine for each 1 milligram of isoleucine. Combination supplements that provide all three of the BCAAs may be more convenient. An excessively high intake of leucine has also been linked to the development of pellagra, a deficiency of the vitamin niacin that causes dermatitis, diarrhea, and mental disorders.
3. Too much leucine in the diet can disrupt liver and kidney function and increase the amount of ammonia in the body. People with impaired liver or kidney function should not take isoleucine without first consulting a physician, as large doses of amino acids may aggravate these conditions.

During times of starvation, stress, infection, or recovery from trauma, the body mobilizes leucine as a source for gluconeogenesis (the synthesis of blood sugar in the liver) to aid in the healing process. 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. Therapeutic use of leucine occurs at doses between 500 and 1,000 mg per day.

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.

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.

Method of Action:
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. Leucine supplementation should not be employed in these individuals.
Degradation of the branched-chain amino acids creates a series of branched fatty acid starter pieces, whose utilization leads to the formation of fatty acids that can be incorporated into complex phospholipids. The branched-chain amino acids have a unique muscle-sparing ability due to their gluconeogenic activity.
 
Daily requirement:
Foods high in isoleucine include:
· Cottage cheese (dry) 4,500 mg/cup
· Cottage cheese (crmd) 3,294 mg/cup
· Fish & other seafoods 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