are trans fatty acids?
One of the most
common questions I get in family practice is about fats in the diet.
While I spend a lot of time discussing saturated and unsaturated
fats, rarely am I asked about trans-fatty acids.
Since the New
England Journal of Medicine released a study in 1997 we have realized
that trans fatty acids are at least as important as saturated fats
in the fight against heart disease.
are essentially a chain of carbon atoms (C) with hydrogen (H) attached
to them. Each carbon atom can attach to four other atoms by means
of a "bond". Sometimes the attachment is by a "double
bond" and only has three other atoms connected to it.
every carbon atom has four single bonds it is a SATURATED FATTY
ACID. When even one carbon atom has less than four single bonds,
i.e. two single and one double bond, it is an UNSATURATED FATTY
unsaturated acids are predominately CIS UNSATURATED. This means
that the hydrogen on the carbon atoms next to the double bond are
on the same side causing a bend. Because of the bend, this type
of fat tends to be liquid at room temperatures.
The food industry
obviously does not want liquid fat in their crackers, cookies, pastries,
cakes, snack chips, imitation cheese, and candies. And, health conscious
America did not want saturated fats, so they changed the shape of
the fatty acid by "HYDROGENATION". This is a high temperature
process whereby hydrogen is added using a chemical catalyst. During
this process they can move the missing hydrogen positions to make
a straight, TRANS UNSATURATED fatty acid molecule.
This type of
fatty acid has a melting point of 44° C, which is above room
temperature. Compare that to cis-fatty acid which melts at 13°
C and saturated fatty acids which melt at 72° C. Unfortunately,
these artificial fatty acids also become part of our bodies cells
small amount of trans fatty acids exists naturally in nature. Some
plants such as pomegranates, peas, and cabbage. Bacteria in the
digestive tract of cows and other grazing animals ferment the food
and creates a small amount of trans acids. We then eat them in the
form of meat and dairy products which is about 3-5% trans.
contain 11-49% trans fatty acids, while some cooking oils can have
even higher amounts. Soft margarine has lower levels that stick
margarine's. Our fast food diet of doughnuts, fried chicken, french-fries,
chips, etc. have 35-38% of trans fatty acids.