On Tue, 1 Aug 2000, Amadeus Schmidt wrote:

> Cell membranes and other EFA functions (in brain and nerves) similarily need
> converting enzymes, which could be crowded out by SFAs.

Why do cell membranes need EFAs?

> And high saturated fat intake is very unprobable in any savannah
> yearmillion. Because wild game is very lean. And wild game is high in EFAs.
> Arctic animals, which are fat are very rich of EFAs of marine source
> (Erasmus notes that too).

I agree that the muscle meat of wild game is very lean.  My
bowhunting friends tell me, however, that even deer have
substantial kidney fat deposits, and these structural fats are
highly saturated.

> Conclusion:
> Beef which isn't grasfed only (nor fattened on grain) is unpaleo.
> And its unpaleoness implies well documented health dangers.

Overstated, I think.  Even feedlot beef fat is also quite high in
monounsaturated fats.  What they are clearly deficient in is EPA
and DHA.  It is therefore important to find other sources for
these, but the absolute amounts needed are still quite small.
Note, for example, that fish oil studies show a ceiling effect
at about three fish servings per week, resulting in w-3 intakes
averaging less than a gram a day.

> >Second, according to references in the Allan and Lutz book that I
> >just read, SFAs are the *preferred fuel* of the heart, but
> >endogenous SFAs are not a significant source of energy for the
> >heart, which entails that the main source would be dietary.
>
> That makes sense for the heart, which is a very constant energy demanding
> organ, without much variation. It uses fat, as the most reliable and long
> term - low impact fuel. It can spare glucose for the brain in this way.
> It also makes sense to have this motor use fuels, which are otherwise not so
> valuable. Of course saturated fats are burned first to spare EFAs.
> For this purpose heart muscle has a quite special composition.

Yes, but putting this into perspective, the heart muscle works
continuously, requiring a significant amount of fuel.  If its
preferred fuel is *dietary* SFAs then that implies that, in a
design sense, the heart "expects" a fair amount of SFA in the
diet.  The fact is that SFAs are, in general, good fuel, and not
just for the heart.  This is undoubtedly why, when glucose is
converted to fat, it is converted to saturated fat.

> Algae have DHA? which?

I don't know, but DHA from algae is available in health food
stores here.

> > Similarly, n-3 fatty acids (18:3n-3, 20:5n-3,
> >22:5n-3, and 22:6n-3) accumulated to a greater extent when n-3
> >fatty acids were fed with beef tallow than with safflower oil.
>
> This sounds not as when that saturated fats were especially helpful, but
> worked when they *replaced* w-6 safflor oil.

This certainly would count against your theory that SFAs compete
for the same enzymes as the EFAs.  If that were the case,
replacing w-6 EFA with SFA wouldn't accomplish much.

> But w-6 LA is also an essential substance. I don't consider it helpful
> to totally stop w-6 intake. We need both pathways and both EFAs.

It would be just about impossible to do so.

Todd Moody
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