Definitions of Diet / Fat Terms

    Here are brief definitions of the key terms important to an
understanding of the role of fat in the diet.
Cholesterol: A chemical compound manufactured in the body. It is
used to build cell membranes and brain and nerve tissues.
Cholesterol also helps the body make steroid hormones and bile
acids.

Dietary cholesterol: Cholesterol found in animal products that are
part of the human diet. Egg yolks, liver, meat, some shellfish, and
whole-milk dairy products are all sources of dietary cholesterol.
Fatty acid: A molecule composed mostly of carbon and hydrogen
atoms. Fatty acids are the building blocks of fats.  

Fat: A chemical compound containing one or more fatty acids. Fat is
one of the three main constituents of food (the others are protein
and carbohydrate). It is also the principal form in which energy is
stored in the body.

Hydrogenated fat: A fat that has been chemically altered by the
addition of hydrogen atoms (see trans fatty acid). Vegetable oil
and margarine are hydrogenated fats.
Lipid: A chemical compound characterized by the fact that it is
insoluble in water. Both fat and cholesterol are members of the
lipid family.

Lipoprotein: A chemical compound made of fat and protein.
Lipoproteins that have more fat than protein are called low-density
lipoproteins (LDLs). Lipoproteins that have more protein than fat
are called high-density lipoproteins (HDLs). Lipoproteins are found
in the blood, where their main function is to carry cholesterol.
Monounsaturated fatty acid: A fatty acid that is missing one pair
of hydrogen atoms in the middle of the molecule. The gap is called
an "unsaturation." Monounsaturated fatty acids are found mostly in
plant and sea foods.

Monounsaturated fat: A fat made of monounsaturated fatty acids.
Olive oil and canola oil are monounsaturated fats. Monounsaturated
fats tend to lower levels of LDL-cholesterol in the blood.
Polyunsaturated fatty acid: A fatty acid that is missing more than
one pair of hydrogen atoms. Polyunsaturated fatty acids are mostly
found in plant and sea foods.

Polyunsaturated fat: A fat made of polyunsaturated fatty acids.
Safflower oil and corn oil are polyunsaturated fats.
Polyunsaturated fats tend to lower levels of both HDL-cholesterol
and LDL-cholesterol in the blood.

Saturated fatty acid: A fatty acid that has the maximum possible
number of hydrogen atoms attached to every carbon atom. It is said
to be "saturated" with hydrogen atoms. Saturated fatty acids are
mostly found in animal products such as meat and whole milk.
Saturated fat: A fat made of saturated fatty acids. Butter and lard
are saturated fats. Saturated fats tend to raise levels of LDL-
cholesterol ("bad" cholesterol) in the blood. Elevated levels of
LDL-cholesterol are associated with heart disease.

Trans fatty acid: A polyunsaturated fatty acid in which some of the
missing hydrogen atoms have been put back in a chemical process
called hydrogenation. Trans fatty acids are the building blocks of
hydrogenated fats. n
 
--E.M.
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.