In today's (Sept 22) issue of Science Dr. Leonard Guarente reports that he's
found exactly why caloric restriction leads to longer life; at least he's found the
mechanism that works yeast and strongly suspects the same thing is true of all
life. Caloric restriction has extend the life of every species it has been tested in.
The key is a gene called SIR2 , the protein it produces clads to parts of the DNA helix,
covering it up and in effect turns off other genes that are supposed to be turned off.
But for the gene to make this cladding protein it needs a substance called NAD, and it
turns out NAD is also used in glucose metabolism, so if you eat a lot there is less NAD
available to make this very important cladding protein.
There is talk of a pill. Geneticist Tomas Prolla referring to life extension says
"I don't think a 30 to 40% range should be considered some kind of maximum.
John K Clark jonkc@att.net
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