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EMBARGOED UNTIL
MONDAY, APRIL 19, 2004
Contact: Donna Krupa
703.967.2751 (cell)
703.527.7357 (office)
djkrupa1@aol.com
APS Newsroom: April 17-21, 2004
Washington, DC Convention Center
East Registration Area/Flex Unit
Telephone: 202.249.4009
Trans Fat Linked To Increase
In Cholesterol
An
animal study bolsters the government’s concern about foods with hydrogenated
oils,
as deadline for food labeling nears
Washington, DC
– The government’s direct assault on obesity and cardiovascular disease has
at least one target in its sights: “trans fat,” better known as the
by-products hydrogenated oils, hydrogenated vegetable oils, margarine,
partially-hydrogenated oils, and vegetable shortening.
Trans Fat Food Content Must Be Labeled In 2006
Trans fatty acids (or “trans fat”) are found in some
margarines, crackers, candies, baked goods, cookies, snack foods, fried
foods, salad dressings, and many processed foods. In 2003, the Food and
Drug Administration (FDA) issued a regulation requiring manufacturers to
list trans fatty acids, or trans fat, on the Nutrition Facts panel of foods
and some dietary supplements. Food manufacturers have until Jan. 1, 2006 to
list trans fat on nutrition labels. The FDA estimates that by three years
after that date, trans fat labeling will have prevented from 600 to 1,200
cases of coronary heart disease and 250 to 500 deaths each year.
Outside the US, some
European countries and Australia have already taken steps to reduce trans
fat content in the food supply, as the literature has suggested for some
time that trans fat is linked to an increase in bad cholesterol (LDL-C) and
a reduction in good cholesterol (HDL-C).
What Are Trans Fats?
Trans fats are produced
through hydrogenation, a chemical process by which hydrogen is added to
unsaturated fatty acids. Hydrogenation gets rid of double bonds. In
doing so, the molecular configuration of the fat molecule can change from
the natural “cis” to the “trans” configuration.
A New Study
A team of physiologists have speculated that trans fat
supplementation in a swine model would raise the total to high density
lipoprotein cholesterol ratio TC/HDL-C, a major factor in the progression of
cardiovascular disease. The authors of the study, “Trans Fat Increases
Total/HDL Cholesterol Ratio in a Porcine Model of Cardiovascular Disease,”
are Kyle K. Henderson, R. Scott Rector, Ying Liu, Tom R. Thomas, James R.
Turk, M. Harold Laughlin, and Michael Sturek, all from the University of
Missouri, Columbia, MO. They will present their findings at the American
Physiological Society’s (APS) (www.the-aps.org)
annual scientific conference, Experimental Biology 2003, being held
April 17-21, 2004, at the Washington, D.C. Convention Center.
Methodology
The primary interest of this research lab is the
cardiovascular system and the beneficial effects of exercise training. For
some of their studies, these investigators use a swine (pig) model. Swine
are an excellent vehicle for understanding the cardiovascular system as
their hearts are similar in size, structure and function as our own.
Pigs that consume a diet of 2% cholesterol
(approximately 40 eggs) and coconut oil (approximately 90% saturated fat) so
that 46% of their daily caloric intake is derived from fat, develop early
stages of cardiovascular disease in 20 weeks. This effect is similar to that
seen in 30-year old humans.
For this study the
researchers were interested in developing a blood lipid profile that could
lead to advanced stages of cardiovascular disease. Seven pigs (Yucatan and
Ossabaw) were placed on four different diets. For 30 weeks, pigs consumed a
2% cholesterol diet supplemented with coconut oil that derives 75% of their
kcal from fat. These pigs were then taken to the catheter lab to assess
atheroma formation in the coronary artery. Atheroma formation was similar
to that observed with the previous studies that lasted 20wks and derived
46%kcal from fat. Researchers then examined the effects of various two week
diets before sacrificing the pigs. For two weeks the pigs returned to the
46% high fat diet as a “wash-out” for the previous diet. The pigs were then
placed on a 2% cholesterol diet but the coconut oil was substituted with
hydrogenated soybean oil, which increased the trans-fat content from 0% to
48% but reduced the saturated fats from 90% to 20%. This trans fat diet
derived 75% of the kcal from fat.
Finally, since
previous data suggested that once a day feeding leads to a more atherogenic
blood profile, the researchers investigated whether twice a day feeding
would alter the lipid profile vs. the standard once a day feeding using the
46% kcal coconut oil based diet.
Blood was taken at the conclusion of the various diets
6hrs after a meal. Blood samples were measured for: TC, TG, HDL-C, LDL-C,
VLDL and LDL1-5. The ratios TC/HDL-C and LDL-C/HDL-C were also calculated.
Results
When the researchers
compared the zero trans vs. the trans diets (same kcal from fat but zero
trans vs. 48% trans fat) they found that:
-
in two
weeks, there was a significant increase in total cholesterol (TC) and LDL-C;
-
the
ratios TC/HDL-C and LDL-C/HDL-C were significantly increased with the trans
fat diet in two weeks;
-
triglycerides after the various meals (6hrs post-meal) were significantly
greater after T75 vs. C75;
-
there
were no differences in Yucatan vs. Ossabaw responses; and
-
at the
end of the study, in an Ossabaw pig, the circumflex coronary artery had an
advanced lesion.
Conclusions
The trans fat diet (T75) significantly increased total
cholesterol, LDL-C, TC/HDL-C and LDL-C/HDL-C ratios in two weeks compared to
the isocaloric diet with zero trans fat (C75). Further triglycerides were
significantly greater six hours after the trans fat meal vs. the isocaloric
zero trans meal. Increasing the fat content did not augment an atherogenic
blood lipid profile. Therefore, these data suggest that a diet high in trans
fat has the potential to promote the rapid development of cardiovascular
disease in swine models.
- end -
The
American Physiological Society (APS) was founded in 1887 to foster basic and
applied science, much of it relating to human health. The Bethesda, MD-based
Society has more than 11,000 members and publishes 3,800 articles in its 14
peer-reviewed journals every year.
***
Editor’s
Note: For further information or to schedule an interview with a member of
the research team, please contact Donna Krupa at 703.967.2751 (cell),
703.527.7357 (office) or at
djkrupa1@aol.com. Or contact the APS newsroom at 202.249.4009 between
9:00 AM and 6:00 PM EDT April 17-21, 2004.
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