Information On Leucine
Leucine is an essential amino acid, needed in the diet; the
human body cannot synthesize it from simpler metabolites. Young adults
need about 31 mg of this amino acid per day per kilogram (14 mg per lb)
of body weight. Leucine can be degraded 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 subtance
from nature to a white, crystalline state was considered noteworthy.
The stucture of leucine was established by laboratory synthesis in 1891.
It's needed not only for protein synthesis but also for a sound
immune system. Some infants can't metabolize leucine (or Isoleucine or
Valine), which causes a condition known as maple syrup urine disease.
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.
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.
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.
Because leucine contributes to gluterine synthesis, taking
supplemental leucine before and after intense training and between
meals can help normalize glutimine levels in both the serum and muscle,
thereby promoting anticatabolic muscle metabolism as well as supporting
immune function.
Leucine appears to be the most important BCAA for athletes, as it
can affect various anabolic hormones, and have an effect on preventing
protein degradation. HMB is a metabolite of Leucine.
Researchers have expended a considerable amount of effort on
evaluating the effects of supplementation of branched-chain amino acids
(BCAAs: leucine, isoleucine, and valine) on physiological and
psychological responses to exercise. There are two primary hypotheses
regarding the ergogenic value of supplementation with these amino acids.
First, BCAA supplementation has been reported to decrease
exercise-induced protein degradation and/or muscle enzyme release (an
indicator of muscle damage) possibly by promoting an anti-catabolic
hormonal profile. Theoretically, BCAA supplementation during intense
training may help minimize protein degradation and thereby lead to
greater gains in fat-free mass. Although several studies support this
hypothesis, additional research is necessary to determine the long-term
effects of BCAA supplementation during training on markers of
catabolism, body composition, and strength.
Second, the availability of BCAA during exercise has been theorized
to contribute to central fatigue. During endurance exercise, BCAAs are
taken up by the muscles rather than the liver in order to contribute to
oxidative metabolism. The source of BCAAs for muscular oxidative
metabolism during exercise is the plasma BCAA pool, which is
replenished through the catabolism of whole body proteins during
endurance exercise.
Leucine is an essential amino acid, needed in the diet; the
human body cannot synthesize it from simpler metabolites. Young adults
need about 31 mg of this amino acid per day per kilogram (14 mg per lb)
of body weight. Leucine can be degraded 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 subtance
from nature to a white, crystalline state was considered noteworthy.
The stucture of leucine was established by laboratory synthesis in 1891.
It's needed not only for protein synthesis but also for a sound
immune system. Some infants can't metabolize leucine (or Isoleucine or
Valine), which causes a condition known as maple syrup urine disease.
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.
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.
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.
Because leucine contributes to gluterine synthesis, taking
supplemental leucine before and after intense training and between
meals can help normalize glutimine levels in both the serum and muscle,
thereby promoting anticatabolic muscle metabolism as well as supporting
immune function.
Leucine appears to be the most important BCAA for athletes, as it
can affect various anabolic hormones, and have an effect on preventing
protein degradation. HMB is a metabolite of Leucine.
Researchers have expended a considerable amount of effort on
evaluating the effects of supplementation of branched-chain amino acids
(BCAAs: leucine, isoleucine, and valine) on physiological and
psychological responses to exercise. There are two primary hypotheses
regarding the ergogenic value of supplementation with these amino acids.
First, BCAA supplementation has been reported to decrease
exercise-induced protein degradation and/or muscle enzyme release (an
indicator of muscle damage) possibly by promoting an anti-catabolic
hormonal profile. Theoretically, BCAA supplementation during intense
training may help minimize protein degradation and thereby lead to
greater gains in fat-free mass. Although several studies support this
hypothesis, additional research is necessary to determine the long-term
effects of BCAA supplementation during training on markers of
catabolism, body composition, and strength.
Second, the availability of BCAA during exercise has been theorized
to contribute to central fatigue. During endurance exercise, BCAAs are
taken up by the muscles rather than the liver in order to contribute to
oxidative metabolism. The source of BCAAs for muscular oxidative
metabolism during exercise is the plasma BCAA pool, which is
replenished through the catabolism of whole body proteins during
endurance exercise.
- Kreider RB (1998). Central fatigue hypothesis and overtraining. In
Kreider RB, Fry AC, O?Toole M (editors), Overtraining in Sport (pages
309-31). Champaign, Illinois: Human
Kinetics - Wagenmakers AJ (1998). Muscle amino acid metabolism at rest and
during exercise: role in human physiology and metabolism. In Holloszy
JO (editor): Exercise and Sport Sciences Reviews (pages 287-314).
Baltimore, Maryland: Williams & Wilkins - Coombes J, McNaughton L (1995). The effects of branched chain amino
acid supplementation on indicators of muscle damage after prolonged
strenuous exercise. Medicine and Science in Sports and Exercise 27,
S149 - Newsholme EA, Parry-Billings M, McAndrew M et al (1991).
Biochemical mechanism to explain some characteristics of overtraining.
In Brouns F (editor): Medical Sports Science, Vol. 32, Advances in
Nutrition and Top Sport (pages 79-93). Basel, Germany: Karger
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