I just found this and I'd like to know what people who believe
saturated fats are healthy and necessary for health think of this
study. I too believed that it wasn't proven that sat fat caused
cardiocircolatory disease, there was just a correlation but a
correlation can be interpreted in many different ways. But this study
seems to prove once and for all that does exist a mechanism which makes
saturated fat unhealthy

Scientists have identified a molecular mechanism in the liver
that explains how consuming foods rich in saturated fats and
trans-fatty
acids can send blood levels of cholesterol and triglycerides soaring.

US researchers report that the harmful effects of saturated and trans
fats
are set in motion by a biochemical switch, or co-activator, in liver
cells
called PGC-1beta.

Their findings shed light on the ongoing dilemma in scientific circles
as to
how saturated and trans fats cause an increase in blood cholesterol and
triglycerides, while diets high in unsaturated and polyunsaturated fats
do
not.

"What we have found is a missing link, a mechanism by which saturated
fats
and trans fats can do their dirty work," said Bruce Spiegelman,
involved in
the research at the US Dana-Farber institute.

Their findings could open up opportunities for food scientists
currently
working on technologies to slice out harmful trans fats from their food
formulations.

Trans fatty acids (TFAs) are formed when liquid vegetable oils go
through a
chemical process called hydrogenation. Hydrogenated vegetable fat is
used by
food processors because it is solid at room temperature and has a
longer
shelf life.

But mounting evidence suggests the TFAs raise LDL (bad) cholesterol
levels,
causing the arteries to become more rigid and clogged. An increase in
LDL
cholesterol levels can lead to heart disease.

Demand for trans fat free food products is pushing new product
developments,
particularly in the US where incoming rules mean that by 1 January 2006
all
trans fats in food products will have to be labelled on the nutritional
panel.

Europe has yet to introduce a similar rule, but consumer organisations
are
pressing for such transparency and food makers are feeling market
pressure
to slice TFAs from their products.

In 2003 Denmark became the first country in the world to introduce
restrictions on the use of industrially produced trans fatty acids.
Oils and
fat are now forbidden on the Danish market if they contain trans fatty
acids
exceeding 2 per cent.

Reporting their findings in Cell, the researchers report that when
activated
by harmful fats, PGC-1beta alters liver metabolism through a cascade of
biochemical signals.

The result is an upsurge in the liver's production of very low-density
lipoprotein (VLDL) cholesterol, the precursor of low-density
lipoprotein
(LDL), or 'bad' cholesterol and triglycerides - another fatty substance
-
that are secreted into the bloodstream.

PGC-1beta belongs to a specific family of co-activators, proteins that
interact with other proteins to turn genes on and off and adjust their
activity, like a dimmer switch that varies the brightness of a light,
say
the scientists.

Co-activators join with other regulatory proteins called transcription
factors in controlling the expression of genes.

The Dana-Farber researchers made the discovery in searching for the
function
of PGC-1beta co-activator that was isolated in 2002.

Experiments including the measurement of gene activity by microarrays
showed
that saturated and trans fats caused greater activity of the gene that
makes
PGC-1beta co-activator than did unsaturated fats.

The research also showed that when the fats triggered PGC-1beta, the
co-activator interacted physically and turned up the function of sterol
responsive element binding proteins.

These important parts of the mechanism activate many key genes of lipid
biosynthesis involving the pathways of cholesterol and triglycerides;
these
genes directed the liver to manufacture more cholesterol, which it does
in
the form of very low-density lipoproteins.

The investigators noted that in mice fed high-fat diets, the PCG-1beta
mechanism actually decreased cholesterol in the liver while increasing
it in
the bloodstream.

Full findings are published in the 28 January issue of Cell.

Joining other ingredients firms reaching out to target trans fat free
formulations, US firm Cargill and Germany's Bayer CropScience announced
a
link up this week to bring a new speciality oil to market. The oil will
not
require hydrogenation, stated the two firms, that have combined their
technologies on seed development to create the product.

Last year US firms Dow AgroSciences, Bunge and DuPont all launched
their
various brands of zero or low trans fat oils, joining ADM's NovoLipid.
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Thanks
Davide