I thought I throw in a couple comments on the aspirin discussion.

As someone has already pointed out, aspirin works by inhibiting
the production of thromboxane, one of the so-called series-2
eicosanoids.  It does this by affecting one of the desaturase
enzymes.  I believe it downregulates the delta-6 desaturase
(D6D), but don't quote me; this is off the top of my head.  It
may work instead on one of the other enzymes in the metabolic
pathway from linoleic acid to thromboxane.

Anyway, aspirin not only inhibits thromboxane production, it also
inhibits production of some of the "good" eicosanoids that are
derived from LA, such as prostaglandin E-1 (PGE1).  Sometimes
this is an acceptable trade-off, in the short run.

For long term use, however, it's important to ask why thromboxane
levels should require continuous reduction.  One answer is that
they are continuously elevated due to dietary imbalances.  Two
known imbalances that cause this are elevated insulin levels and
a too-high ratio of w-6 to w-3 fats in the diet.  Correcting
these imbalances by means of a reduced carb diet with adequate
w-3 fats should correct the problem without also inhibiting the
production of PGE1 and other useful eicosanoids.

Aspirin is sometimes associated with excessive bleeding and
hemorrhages precisely because of its anti-thromboxane properties,
since thromboxane is the messenger hormone that triggers
clotting.  A diet that contains excessive w-3 fats may also have
this effect.  The Japanese, who consume more w-3 fats than
Americans do, are less likely to have heart attacks, which are
often caused by clotting phenomena, but more likely to have
cerebral hemorrhages.  They eat relatively litte saturated fat,
but saturated fat apparently has a protective effect against
strokes.  I don't know why this is, but it could be by
upregulating insulin, since saturated fat increases insulin
resistance.  We consider insulin resistance to be a bad thing,
but it may not be so bad as a counterbalance to excessive w-3 fat
consumption.

None of this means that we shouldn't take an aspirin if we need
one, or even that we shouldn't use it on a regular basis.  I do
think, however, that it needs to be carefully considered,
especially by a person on a low-carb paleo diet.  That diet may
already accomplish what the daily aspirin was supposed to do, and
taking the aspirin in addition could push the balance too far in
the other direction.  It ought to be possible to check this by
means of blood work, but I'm uncertain as to what the exact test
would be.

Todd Moody
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