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Caloric restriction and mitochondrial fatty acid composition

Aubrey de Grey ag24 at mole.bio.cam.ac.uk
Thu Jan 21 07:27:40 EST 1999

Tom Matthews wrote:

> I am confused. How can CR "*decreases* unsaturation" and at the same
> time "increases levels of (the extremely unsaturated) docosahexaenoic
> acid"?

Quite right -- the docosahexaenoate result is very intriguing precisely
because it is in conflict with the other papers I cited.  Sorry if I
wasn't clear.  I have been meaning to write to Cefalu about this; I'll
mention anything I discover. 

> Are you saying that
> this more DHA under CR is, in fact, a potentially life-span *decreasing*
> effect of CR?

Yes.  Of course docosahexaenoate is a relatively rare constituent of
mitochondrial membranes, so the overall peroxidisability is not much
affected by it: the ratio of linoleate to arachidonate is what matters
most.  Thus, there could in principle be some independent advantage of
high docosahexaenoate which can be accommodated by a really big shift in
the arachidonate-to-linoleate ratio.  However, Pamplona et al did find
that pigeons have a lot less docosahexaenoate than rats, as well as
less arachidonate per linoleate.  All in all, until I see Cefalu's
result in print I'm inclined to guess that it is in error, i.e. that
docosahexaenoate is reduced by CR.

Aubrey de Grey

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