From: rbradbur@hardy.u.washington.edu (Robert Bradbury)
Subject: Both type and amount of fats are important [was: spoiled food]
Summary: Cooking/spoilage characteristics are not equal to disease causes
Organization: University of Washington, Seattle
Date: Mon, 16 Nov 1992 13:59:25 GMT

In article <BSIMON.92Nov16072807@elvis.stsci.edu> bsimon@elvis.stsci.edu (Bernie Simon) writes:
>In article <15381@sunfse.ese.lmsc.lockheed.com> news@sunfse.ese.lmsc.lockheed.com (news) writes:
>
>   I believe the major oxidation problem is with *solidified* oils and fats,
>   that is, saturated and "partially hydrogenated".  The liquid vegatable
>   oils do not fall in this category (they are either mono- or 
>   poly-unsaturated), and thus are less of a risk for oxidation.
>
>No, the situation is exactly the reverse. Polyunsaturated oils have a
>higher rate of oxidation than saturated oils and thus increase the
>risk of cancer. However, saturated oils and fats are worse for your
>heart. The best solution is to reduce your consumption of all kinds of
>fats and use mono-unsaturated oils when you do use oils.
>Polyunsaturated oils should only be used cold, for things like salad
>dressing, because heating increases oxidation.
>

Please do not confuse cooking and storage characteristics with disease
causing characteristics.  Saturated fats are solid at room temp and
seem to play a role in heart disease probably by increasing your
cholesterol exposure/synthesis levels.  Unsaturated fats are liquid
at room temp and seem to be associated higher cancer rates probably
because their metabolism increases DNA damage.  Partially hydrogenated
fats are unsaturated fats which have been chemically modified to
make them more solid at R.T. (so your corn oil based margarine is
more like butter).  Monosaturated oils seem to be the least harmful
of the lot.

The oxidation properties of an oil affect its taste.  I have seen 
nothing which indicates a relation to disease.  (Given the taste it would
be hard to get animals/humans to consume oxidized oils in experiments.)

I suspect that in fact the degree of saturatedness of an oil is
unrelated to its disease causing ability.  I believe there are
enzymes which deal equally well with the saturated and unsaturated
forms of the fatty acids which compose fats and oils.  The real issue 
(IMHO) is how long the fatty acids chains actually are.  Longer chain 
fatty acids seem to be metabolized first in peroxisomes which will
result in the production of hydrogen peroxide.  Shorter chain fatty 
acids seem to go directly to the mitochondria for metabolism and 
probably produce less damage.  The various oils/fats which we consume
have different ratios of long:short chain fatty acids and these
can vary depending on the environment in which the plant/animal
was raised.  There seem to be only a few studies which relate
fatty acid chain length to disease and so my only recomendation
would probably be that "shorter" is better.  In dietary terms
that probably equates to more liquid  (less viscous) oils.

In any situation, less fat is better.  I believe the only fat
requirement is for about a teaspoon of linoleic acid per day.
Someone with some nutrition books may want to elaborate on that.

Newsgroups: sci.med.nutrition