leucine may eliminate sarcopenia
Doug Skrecky
Feeling Old? Supplement Diet With Leucine Prevents Muscle Loss Linked To
Aging
Muscle in adults is constantly being built and broken down. As young
adults we keep the two processes in balance, but when we age breakdown
starts to win. However, adding the amino acid leucine to the diet of old
individuals can set things straight again. This is the finding of
research performed by Lydie Combaret, Dominique Dardevet and colleagues at
the Human Nutrition Research Centre of Auvergne, INRA, Clermont-Ferrand,
France.
After the age of 40, humans start loosing muscle at around 0.5-2% per
year. Immediately after a meal degradation of protein slows down and
synthesis doubles. This process is triggered by the arrival of a
plentiful supply of amino acids. In older animals this stimulus is less
effective; synthesis slows down, and previous work also suggests that
breakdown may be affected. While adding leucine to the diet restores
protein building there was no knowledge about this supplement's effect on
breakdown.
To address this, researchers compared protein breakdown in young
(8-month) and old (22-month) rats. They discovered that the slow down in
degradation that normally follows a meal does not occur in old animals,
so there is excessive breakdown. But adding leucine to the diet restored
a balanced metabolism.
The team of researchers believe that the age-related problem results from
defective inhibition of ubiquitin-proteasome dependent proteoloysis, a
complex degradative machinery that breaks down contractile muscle
protein, and that leucine supplementation can fully restore correct
function.
"Preventing muscle wasting is a major socio-economic and public health
issue, that we may be able to combat with a leucine-rich diet," says
senior co-author Didier Attaix.
Commenting on the work Michael Rennie from the University of Nottingham
Medical School at Derby says: "This is exciting because it strengthens
the idea of a co-ordinated linkage between the meal-related stimulation
of protein synthesis and the inhibition of breakdown."
RArmant
<oberonS...@vcn.bc.ca> wrote:
>[Any high protein diet contains plenty of leucine.]
From the abstract:
Next, we tested the hypothesis that the ingestion of a 5%
leucine-supplemented diet may correct this defect. Leucine
supplementation restored the postprandial inhibition of in vitro
proteasome-dependent proteolysis in 22-month-old animals, by
down-regulating both rates of ubiquitination and proteasome activities.
The complete paper can be found at:
http://jp.physoc.org/cgi/content/full/569/2/489
RArmant
>On Fri, 9 Dec 2005 19:21:32 +0000 (UTC), Doug Skrecky
><oberonS...@vcn.bc.ca> wrote:
>
>>[Any high protein diet contains plenty of leucine.]
>
>From the abstract:
>
>Next, we tested the hypothesis that the ingestion of a 5%
>leucine-supplemented diet may correct this defect. Leucine
>supplementation restored the postprandial inhibition of in vitro
>proteasome-dependent proteolysis in 22-month-old animals, by
>down-regulating both rates of ubiquitination and proteasome activities.
5% leucine relative to what? If this is relative to calories -- for a
2000 Calorie diet the amont of leucine would be 100 Cal or
25 grams.
beni
is there any connection to collagen production rate in the body to
this?
beni
Kofi
attenuate proteolysis in skeletal muscle in cancer-induced muscle loss
[PMID 15665304] by attenuating the ubiquitin-proteasome proteolytic
pathway which in its aging, dysregulated state leads to sarcopenia via
less protein synthesis; EPA is also an inhibitor of the tumor factor
proteolysis-inducing factor (PIF) upregulation of proteasome expression;
EPA and HMB blocked proteasome 20S alpha and beta-subunits as well as
19S; the major event in PIF-induced protein degradation is the release
of arachidonic acid (attenuated by EPA but not HMB); both EPA and HMB
blocked downstream activation of protein kinase C (PKC), degradation of
inhibitor kappaBalpha (which would activate NFKB) and phosphorylation
p42/44 MAPK [PMID 15574784]
HMB also works against cachexia in rheumatism (with arginine and
glutamine) [PMID 15896432] and AIDS [PMID 11366220]
beta-hydroxy-beta-methylbutyrate (HMB), lysine and arginine slowed
protein breakdown and blunted the gradual loss of muscle in elderly
women [PMID 15105032]
cytokines, glucocorticoids, PIF and oxidative stress are thought to be
responsible for increased muscle protein degradation in a variety of
conditions (sepsis, burns, severe trauma) through increased proteasome
degradation (via NFKB activation); ubiquitin attaches to myosin and
degrades it at a faster rate; insulin suppresses this proteasome
pathway; NFKB inhibitors (thalidomide, resveratrol, EPA and HMB) are
effective anti-cachexia agents as are glucocortidcoid antagonists (in
sepsis) [PMID 15915823];
Since the low GI diet lowers NFKB, it stands to reason that it also
blocks muscle loss.
beni
isoleucine and valine also?
How much to supplement?
thanks.
beni.
Thomas Carter
Protein consumption is not equivalent to amino acid
supplementation. Proteins are absorbed as peptides, not amino acids and
the final breakdown to individual amino acids probably takes place in
the ribosome adjacent to protein building. The study of amino acid
supplementation is not far along compared to that of other popular
nutrients, but what is being seen is near unanimity in beneficial
papers.
Nonessential amino acids are even less well studied, perhaps
because of a failure to appreciate the above argument. Never the less
essential amino acids are probably very effective in muscle maintenence
and diabetes. See an old post of mine on this subject, which I think
included the paper below.
Thomas
(5) Am Heart J. 2004 Jun;147(6):1106-12. Related Articles, Links
Effects of oral amino acid supplementation on myocardial function in
patients with type 2 diabetes mellitus.
Scognamiglio R, Negut C, Piccolotto R, Dioguardi FS, Tiengo A, Avogaro
A.
Division of Cardiology, Department of Clinical and Experimental
Medicine, University of Padova Medical School, Padova, Italy.
r.scogn...@unipd.it
BACKGROUND: Diabetes mellitus is associated with an
increased rate of cardiac amino acid catabolism that could interfere
with cardiac function. METHODS: We assessed the effects of an oral
amino acids mixture (AAM) on myocardial function in patients with type
2 diabetes mellitus (DM2). We studied 65 consecutive patients with DM2
who had normal resting left ventricular ejection fraction (LVEF) and
did not have obstructive coronary artery disease (CAD). After baseline
evaluations, patients were randomized to receive, in a single-blinded
fashion, AAM (12 grams/day) or placebo for 12 weeks, after which,
treatment was crossed over for another similar period. At baseline and
at the end of each treatment, 2-dimensional ecocardiography at rest and
during isometric exercise (handgrip) was performed, as were biochemical
assays. Twenty adults, matched for age, sex, and body mass index served
as control subjects. RESULTS: At baseline and during AAM or placebo
treatment, resting left ventricular dimensions and LVEF in patients
with DM2 did not differ from those of control subjects. In patients
with DM2, at baseline and during placebo treatment, peak handgrip LVEF
decreased significantly in comparison with the resting value (63% +/-
9% vs 56% +/- 9%, P <.001; and 62% +/- 6% vs 55% +/- 8%, P <.001).
During AAM treatment, peak handgrip LVEF did not differ from resting
value (66% +/- 11% vs 64% +/- 9%, P = not significant). Thus, exercise
LVEF was higher during AAM treatment than both baseline and placebo
treatment (66% +/- 11% vs 56% +/- 9% and vs 55% +/- 8%, P <.001). In
contrast to placebo treatment, after the AAM supply, a decreased
glycated hemoglobin level was observed (7.0% +/- 1.3% vs 7.6% +/- 1.8%,
P <.05). CONCLUSIONS: Myocardial dysfunction is easily inducible with
isometric exercise in patients with DM2 who have normal resting LV
function and do not have CAD. An increased amino acid supply prevents
this phenomenon and improves metabolic control. From the full
text................
PMID: 15199363
Table II. Composition of the amino acid mixture in gms/day
leucine 3.8
lysine 2
isoleucine 1.9
valine 1.9
threonine 1.1
cystine .4
histidine .4
phenylalanine 1.1
methionine .56
tyrosine .33
tryptophane .22