On Wed, 2 Aug 2000, Amadeus Schmidt wrote:

> More saturated fatty acids make the cell membranes more like saturated fats
> are, in contrast to polyunsaturated fats. Harder, less flexible, less
> permeable to nutrients.

I understand this, in principle, and find it plausible.  But
lately I am having some misgivings.  For one thing, EFAs are
PUFAs, and highly oxidizable.  A high concentration of PUFAs in
cell membranes must make them more susceptible to oxidation
damage, and I doubt this is a good thing.

Second, we *do* have the enzymes for turning SFAs into MUFAs as
needed.  So buildup of SFAs in membranes shouldn't be a problem,
if these enzymes are working.

> This can cause earlier death of cells. In arteries,
> the walls like the membranes become harder and less able to fulfill their
> function. This is a reason for the body to "strengthen" the artery walls by
> deposits of cholesterol.
> This information also explained in the "Fats that Heal, Fats that Kill".

I am very skeptical.  For one thing, arteriosclerosis is not
correlated with fat intake or cholesterol levels *at all*.

> How much does this amount to? Which percentage gives a whole deer's
> fat in saturated fat (including kidney fat, brain, marrow, subcutane)?
> How much lean meat has such a deer?
> If it was about 50kg of muscles, some kg of organs how substantial is the
> kidney fat deposit?  1 lbs? 1kg? more?

I don't know.  They tell me that between the kidney fat and other
local fat deposits, they toss away a fair amount of fat.  Hardly
any of it is intramuscular, of course, so the meat itself is very
lean.  And I'm sure you've considered that many fowl, such as
ducks, also have substantial amounts of fat, a good deal of which
is saturated.  I think water fowl would have been an important
food source.  For example, pheasant is about 9.3% fat, almost a
third of which is saturated.  Wild duck is about 15% fat, about a
third of which is saturated.  In fact, the fat composition of
wild duck is similar to that of feedlot beef.

Now consider organ meats: liver, pancreas, spleen.  If you do a
bit of checking you will find that in almost every case the SFA
content of these foods is greater than the MUFA or PUFA content.
In a few cases, the SFA and MUFA are about equal.  So I'm not
seeing any particular scarcity of SFAs in paleo animal foods.

> Not only saturated, but also monounsaturated fats compete with EFAs
> on enzymes, but to a lesser degree. Then its a matter of EFA compared to
> total fat.

Again, I'd like to see evidence that this competition is a
*problem*.

In particular, I am struck by the good health of many populations
that consume very large amounts of SFA.  George Mann, one of the
directors of the Framingham study, is the one who studied the
Masai, Samburu, and Jamaican people.  The first two eat almost
exclusively meat and dairy (and some blood); the Jamaicans use
large amounts of coconut oil, which is more saturated than any
animal fat.  All have extremely low rates of diabetes and heart
disease.  This isn't what you'd expect if their cell membranes
are turning to stone, is it?

Todd Moody
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