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by Dallas Clouatre, Ph.D.
The new
L-Carnitine
with a focus on MUSCLE and ENERGY
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SOMETIMES, A WELL-KNOWN
and valued supplement can
be transformed to provide
significant new benefits. Such
is the case with L-carnitine.
Propionyl-L-carnitine is a form
that until very recently was
restricted to medical uses.
Now it finally is available more
generally as glycine propionyl-
L-carnitine or GPLC, which
is a patented compound.
Many health food shoppers will
be surprised by the difference
found with this next generation
of L-carnitine. This is the
L-carnitine with a focus on
muscular energy, exercise
recovery and reduced fatigue. |
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L-carnitine is an amino acid supplied in limited quantities by the
diet and also manufactured in the body, mainly in the liver and
the kidneys. Produced from the essential amino acid lysine, the
body’s synthesis of L-carnitine requires the vitamins C, B-6 and
niacin, along with iron and the amino acid methionine. L-carnitine
is concentrated in the heart and the skeletal muscles, and also
in the brain and in the sperm. Its primary role is as a biocatalyst.
It serves to transport fatty acids across the membrane of the cell
and into the mitochondria, where these fatty acids are oxidized
for energy. L-carnitine also aids in the removal of waste products
from the mitochondria. Moreover, it increases the rate of oxidation
of fats in the liver, and this suggests that it plays a role in
improving energy generation from this angle as well. Its impact
upon fat metabolism is sufficient that the Physician’s Desk
Reference has recommended dosages of 600–1200 mg three
times per day for the treatment of some forms of heart disease
and for some conditions involving elevated blood lipids.
L-carnitine supplementation can supply a bundle of benefits.
There is no doubt that a cellular deficiency of L-carnitine can
lead to symptoms such as fatigue, muscle weakness, obesity,
plus elevated blood lipid and triglyceride levels. L-carnitine is
very safe, so supplementation provides insurance in cases
where there may be a question whether or not levels are sufficient.
There are many anecdotal instances in which the supplement
has helped to reduce excess weight, and Jeffrey Bland,
Director of the Bellevue Medical Laboratory, has argued that in
the proper dosages, L-carnitine supplementation during dieting
can help to control the negative effects of ketosis (the accumulation
of waste products of fat metabolism) in those who are
susceptible to this problem. There is also evidence that some
forms of obesity may be related to a genetic propensity to produce
less L-carnitine, and liver and kidney problems will similarly reduce the body’s production since some four-fifths of our
L-carnitine total is produced internally by these organs. Finally,
L-carnitine penetrates into the mitochondria themselves. It is
here that most free radicals are generated as food is oxidized to
produce energy. There is evidence that L-carnitine serves to
spare antioxidants, such as vitamin C, although the mechanism
by which this is done has not yet been uncovered.
Some researchers argue that increasing the level of L-carnitine
in the system does not increase the rate or the amount of fatty
acids used for energy except in cases where L-carnitine has been
deficient, or in cases of special disorders. The experiences of
healthy athletes with supplementation have been mixed.
However, the results with healthy athletes are probably not appropriate for comparison with those of individuals suffering
from excess weight or related difficulties. More importantly, current
findings indicate that the mixed results came about
because earlier researchers did not know what to look for and
were not using the appropriate dosage levels. Furthermore, there is very good reason to believe that in the case of athletes
(and likely also dieters) the wrong form of L-carnitine generally
has been used.
What is meant by the “wrong form” of L-carnitine? Simply
this: L-carnitine comes in two forms that are particularly active,
but active for different purposes. Acetyl-L-carnitine is especially
active in neuronal tissues, whereas propionyl-L-carnitine is
especially active in lean muscle tissue. The form of L-carnitine
supplemented needs to be matched to the purpose intended.
Acetyl-L-carnitine (acetyl carnitine) is involved in the same
metabolic functions as is L-carnitine in its other forms, but
acetyl-L-carnitine offers greater protection for the brain and for
the neurons more generally. As an antioxidant, acetyl-L-carnitine
protects neurons from damage caused by superoxide radicals.
One reason may be that the molecular structure of acetyl-L-carnitine
resembles that of the neurotransmitter acetylcholine.
Research on preventing age-related mitochondrial decay and
declines in mental abilities¡ªperhaps even reversing some agerelated
mental declines¡ªhas stressed the combination of
acety-L-carnitine and alpha-lipoic acid. This combination, furthermore,
appears to prevent the more generalized age-related
decline in metabolic functioning.
 Propionyl-L-carnitine has its own set of strengths. It is used
medically for treating peripheral vascular disease, atherosclerotic
and diabetic angiopathies, and congestive heart failure. In
combination with acetyl-L-carnitine, propionyl-L-carnitine is
used for treating chronic fatigue syndrome and symptoms of
age-related testosterone deficiency. Indeed, it seems to reduce
the symptoms of androgen decline in older men as well as does
testosterone in terms of improvements in sexual dysfunction,
depression and fatigue¡ªbut without the prostate and other
side effects of testosterone supplementation.
The focus of this form of L-carnitine, therefore, is on the muscles,
such as the heart, and the vascular system. Compared with
at least one other form of L-carnitine, propionyl-L-carnitine
appears to produce greater increases in cellular L-carnitine concentrations.
Researchers believe that it is transported more
easily into muscle fibers and may better support muscle-cell
energy production, perhaps because it increases the flow of
pyruvate into the Krebs¡¯ Cycle. Propionyl-L-carnitine also
exhibits significant free radical scavenging activity and helps to
prevent blood from coagulating too readily. Thus, the availability
of GPLC as a non-medical (hence less concentrated)
source of propionyl-L-carnitine is good news. And one should
not forget that the amino acid glycine, which is part of GPLC, has
benefits of its own.
Athletes in particular may be pleased with the benefits of
GPLC. The propionyl-L-carnitine component of GPLC increases
the oxidation of both glucose and lactate, increases exercise
capacity, increases both mental and overall energy, and
improves muscle glycogen stores while increasing time to muscular
fatigue. Of course, like other forms of L-carnitine, propionyl-
L-carnitine improves the function of the mitochondria, and in
those who are overweight it should produce a significant
increase in the rate at which fats are oxidized to supply energy.
In other words, GPLC offers both the expected benefits of
carnitine and improved muscle-specific benefits to athletes and
non-athletes alike.
For references, send a SASE to totalhealth.
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