All
fats are combinations of fatty acids. Nutritionists characterize a dietary fat
or oil as saturated, monounsaturated, or polyunsaturated depending on which
fatty acids make up the largest portion of the fat or oil:
Foods
such as butter, which are high in saturated fatty acids, are solid at room
temperature and get harder when chilled.
Foods
such as olive oil, which are high in monounsaturated fatty acids, are liquid at
room temperature; they get thicker when chilled.
Foods
such as corn oil, which are high in polyunsaturated fatty acids, are liquid at
room temperature and stay liquid when chilled.
So
how come margarine, which is composed primarily of unsaturated fatty acids, is
solid? Because its fatty acids have been artificially saturated with extra
hydrogen atoms. This process, called hydrogenation, turns an oil, such as corn
oil, into a solid fat — margarine.
Hydrogenated
fats are sometimes called trans fatty acids, but no matter what you call them,
these fatty acids raise — rather than lower — cholesterol levels. As a result,
these days most margarines boast “no trans fats” right on the label. I know
your mother told you not to toot your own horn, but these guys have earned the
right. So when you’re shopping, pick them.
