X-Message-Number: 27422
Date: Fri, 9 Dec 2005 11:07:07 -0800 (PST)
From: Doug Skrecky <>
Subject: leucine may eliminate sarcopenia

[Any high protein diet contains plenty of leucine.]

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."

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