Leucine
verhindert spierafbraak bij ouderen.*
Vanaf
het veertigste levensjaar begint bij mensen de hoeveelheid spieren af te nemen
met 0,5 tot 2% per jaar. Normaal worden eiwitten uit de voeding in het lichaam
omgezet tot aminozuren, doch bij het ouder worden vertraagt dit proces waardoor
de spiermassa afneemt. Uit een rattenstudie blijkt nu dat een voeding aangevuld
met het eiwit leucitine een volledige eiwitsynthese kan herstellen waardoor geen
verlies aan spieren nodig is.
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 losing 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." (December 2005) (Opm. Leucine is een essentieel eiwit d.w.z. dat kan het lichaam zelf niet maken en moet uit de voeding opgenomen worden. Vooral de dierlijke eiwitten hebben de meeste essentiële.)
