Consumer
Guide To Fats
Fats and Fatty Acids
Fats are a group of chemical compounds that contain fatty
acids. Energy is stored in the body mostly in the form of
fat. Fat is needed in the diet to supply essential fatty acids,
substances essential for growth but not produced by the body
itself.
There are three main types of fatty acids: saturated, monounsaturated
and polyunsaturated. All fatty acids are molecules composed
mostly of carbon and hydrogen atoms. A saturated fatty acid
has the maximum possible number of hydrogen atoms attached
to every carbon atom. It is therefore said to be "saturated"
with hydrogen atoms.
Some fatty acids are missing one pair of hydrogen atoms
in the middle of the molecule. This gap is called an "unsaturation"
and the fatty acid is said to be "monounsaturated"
because it has one gap. Fatty acids that are missing more
than one pair of hydrogen atoms are called "polyunsaturated."
Saturated fats (which contain saturated fatty acids) are
mostly found in foods of animal origin. Monounsaturated and
polyunsaturated fats (which contain monounsaturated and polyunsaturated
fatty acids) are mostly found in foods of plant origin and
some seafoods.
Polyunsaturated fatty acids are of two kinds, omega-3 or
omega-6. Scientists tell them apart by where in the molecule
the "unsaturations," or missing hydrogen atoms,
occur.
Recently a new term has been added to the fat lexicon: trans
fatty acids. These are byproducts of partial hydrogenation,
a process in which some of the missing hydrogen atoms are
put back into polyunsaturated fats. "Partially hydrogenated
vegetable oils," such as vegetable shortening and margarine,
are solid at room temperature.
Government Advice
Dietary guidelines endorsed by the U.S. Department of Agriculture
and the U.S. Department of Health and Human Services advise
consumers to:
Reduce total dietary fat intake to 30 percent or less of
total calories.
Reduce saturated fat intake to less than 10 percent of calories.
Reduce cholesterol intake to less than 300 milligrams daily
.
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