Chapter 4
The Lipids: Fats
and Oils
© 2007 Thomson - Wadsworth
Ask Yourself
1. The body can store fat in virtually unlimited
amounts.
2. Dietary cholesterol is found only in animal
foods.
3. A person’s blood level of cholesterol is a
predictor of
that person’s risk of having a heart attack.
4. For the health of your heart, the fat you
should avoid eating, most of all, is
cholesterol.
5. The more monounsaturated fats you
consume, the better it is for your health.
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Ask Yourself
6. Fruits are essentially fat-free.
7. In general, the softest margarines are
the most polyunsaturated.
8. Polyunsaturated fat has the same
number of calories as saturated fat.
9. All foods that you eat should contain
less than 10% of calories from
saturated fat.
10. No one is free of atherosclerosis.
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A Primer on Fats
• Lipids: a family of compounds that
includes:
 Triglycerides (fats and oils)
 Phospholipids (lecithin)
 Sterols (cholesterol)
• Obvious sources of fat are oil, butter,
margarine and shortening.
• Other foods contributing fat include
meat, nuts, mayonnaise, salad
dressings, eggs, bacon, gravy, cheese,
ice cream and whole milk.
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A Primer on Fats
• Triglycerides (try-GLISS-er-ides): the
major class of dietary lipids, including fats
and oils.
• Phospholipid (FOSS-foh-LIP-ids): a lipid
similar to a triglyceride but containing
phosphorus; one of the three main classes
of lipids.
• Sterols (STEER-alls): lipids with a structure
similar to that of cholesterol; one of the
three main classes of lipids.
 Cholesterol (koh-LESS-ter-all): one of the sterols,
manufactured in the body for a variety of purposes.
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A Primer on Fats
• Fats: lipids that
are solid at room
temperature.
• Oils: lipids that
are liquid at
normal room
temperature.
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© 2007 Thomson - Wadsworth
A Primer on Fats
• After eating, the body
stores some fat as an
energy reserve.
• The body has unlimited
potential to store fat.
• Excess carbohydrate and
protein can be converted to
fat, but they cannot be
made from fat.
• One pound of body fat is
worth 3,500 calories.
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A Primer on Fats
• Satiety: the
feeling of fullness
or satisfaction
that people feel
after meals.
 Fats slow the rate
at which the
stomach empties.
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A Closer View of Fats
About 95 percent of the
lipids in foods and in the
human body are
triglycerides.
• A triglyceride is made
up of three units known
as fatty acids and one
unit called glycerol.
• Fatty acids: basic units
of fat composed of
chains of carbon atoms
with an acid group at
one end and hydrogen
atoms attached all along
their length.
• Glycerol (GLISS-er-all):
an organic compound
that serves as the
backbone for
triglycerides.
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A Closer View of Fats
• Fatty Acids differ in chain length or
the number of carbons in a fatty
acid.
• Chain length affects solubility.
• Fatty acids can be:
Short-chain
Medium-chain
Long-chain
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A Closer View of Fats
• Fatty Acids differ in the degree of
saturation.
• Saturation refers to the chemical
structure—specifically to the number of
hydrogens the fatty acid chain holds.
 Saturated Fatty Acids are filled to
capacity with hydrogen.
 Unsaturated Fatty Acids hold an “empty
spot” or point of unsaturation.
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The Types of Fatty Acids
• Saturated fatty acid: a fatty acid carrying the
maximum possible number of hydrogen atoms (having
no points of unsaturation). Saturated fats are found in
animal foods like meat, poultry, and full-fat dairy
products, and in tropical oils such as palm and coconut.
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The Types of Fatty Acids
• Unsaturated fatty acid: a fatty acid with one or more
points of unsaturation. Unsaturated fats are found in
foods from both plant and animal sources. Unsaturated
fatty acids are further divided into monounsaturated
fatty acids and polyunsaturated fatty acids.
• Monounsaturated fatty acid: a fatty acid containing
one point of unsaturation, found mostly in vegetable oils
such as olive, canola, and peanut.
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The Types of Fatty Acids
• Polyunsaturated fatty acid:
(sometimes abbreviated PUFA) a fatty
acid in which two or more points of
unsaturation occur, found in nuts and
vegetable oils such as safflower,
sunflower, and soybean, and in fatty
fish.
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© 2007 Thomson - Wadsworth
The Types of Fatty Acids
• Essential fatty acid: a fatty acid that
cannot be synthesized in the body in
amounts sufficient to meet physiological
need.
• Linoleic (lin-oh-LAY-ic) acid,
linolenic (lin-oh-LEN-ic) acid:
polyunsaturated fatty acids, essential
for human beings.
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The Types of Fatty Acids
• Omega-3 fatty acids,
found in fish oils, offer
a protective effect on
health.
 Interest in fish oils was
first kindled when
someone thought to ask
why the Eskimos of
Greenland, who eat a
diet very high in fat,
have such a low rate of
heart disease.
 Blood clot formation,
inflammation (e.g.
arthritis, asthma),
irregular heart rhythm
and cancer also seem to
be beneficially affected
by DHA and/ or EPA.
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Characteristics of Fats in
Foods
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Fatty Acids in Dietary Fats & Oils
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Characteristics of Fats in Foods
• Unsaturated fats are more likely to react with
oxygen and become rancid.
• Food manufacturers may alter fats and oils by:
 hydrogenation (high-droh-gen-AY-shun): the
process of adding hydrogen to unsaturated fat to
make it more solid and more resistant to chemical
change.
 antioxidant (anti-OX-ih-dant): a compound that
protects other compounds from oxygen by itself
reacting with oxygen.
 Emulsifier: a substance that mixes with both fat
and water and can break fat globules into small
droplets, thereby suspending fat in water.
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The Other Members of the
Lipid Family
Phospholipids…
• Important components
of cell membranes.
• Can serve as
emulsifiers in the body,
joining with both water
and fat.
• Also used in foods such
as margarine,
chocolate, salad
dressings, and frozen
desserts to keep the
fats dispersed.
• Widespread in foods.
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The Other Members of the
Lipid Family
Sterols such as
cholesterol…
• Incorporated as an integral
part of the structure of cell
membranes.
• Used to make bile for
digestion.
• Used to make sex
hormones (estrogen and
testosterone).
• Made into vitamin D
• Deposited in the artery
walls, leading to plaque
Sterols such as cholesterol
buildup and heart disease.
have a multiple-ring
structure.
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Five foods contribute up to 70% of the cholesterol in the US diet:
Eggs (30%), Beef (16%), Poultry (12%), Cheese (6%) and milk (5%).
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© 2007 Thomson - Wadsworth
How the Body Handles Fat
• Bile: a mixture of compounds,
including cholesterol, made by the
liver, stored in the gallbladder, and
secreted into the small intestine.
Bile emulsifies lipids to ready them
for enzymatic digestion and helps
transport them into the intestinal
wall cells.
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© 2007 Thomson - Wadsworth
How the Body Handles Fat
• The products of fat digestion are fatty
acids, glycerol and monoglycerides.
 Monoglyceride (mon-oh-GLISS-er-ide): a
glycerol molecule with one fatty acid attached
to it. A diglyceride is a glycerol molecule with
two fatty acids attached to it.
• The shortest fatty acids and glycerol pass
by simple diffusion into the absorptive cells
and without further processing can enter
the blood stream, travel to the liver and be
converted and used by the body.
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How the Body Handles Fat
• Long-chain fatty acids, phospholipids and
cholesterol are insoluble in water and
cannot be accepted by the body’s blood and
lymph system.
 Lymph (LIMF): the body fluid that transports
the products of fat digestion toward the heart
and eventually drains back into the
bloodstream.
• Lymph consists of the same components as blood with
the exception of red blood cells.
• These fats must be packaged into one of
four types of lipoproteins for transport.
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How the Body Handles Fat
• Lipoproteins (LIP-oh-PRO-teens): clusters of
lipids associated with protein that serve as
transport vehicles for lipids in blood and lymph.
The four main types of lipoproteins are:
1. Chylomicron (KIGH-loh-MY-cron): a type of
lipoprotein that transports newly digested fat—mostly
triglyceride—from the intestine through lymph and
blood.
2. VLDL (very-low-density lipoprotein): carries fats
packaged or made by the liver to various tissues in the
body.
3. LDL (low-density lipoprotein): carries cholesterol
(much of it synthesized in the liver) to body cells. A high
blood cholesterol level usually reflects high LDL.
4. HDL (high-density lipoprotein); carries cholesterol in
the blood back to the liver for recycling or disposal.
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© 2007 Thomson - Wadsworth
“Good” vs. “Bad” Cholesterol
• Oxidized LDLcholesterol (o-LDL): the
cholesterol in LDLs that is
attacked by reactive
oxygen molecules inside
the walls of the arteries.
 o-LDL is taken up by
scavenger cells and
deposited in plaque.
• Foam cells: cells from the
immune system containing
scavenged oxidized LDL
cholesterol that are
thought to initiate arterial
plaque formation.
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“Good” vs. “Bad” Cholesterol
• ATHEROSCLEROSIS: As LDL particles
penetrate the walls of the arteries, they
become oxidized-LDL and next are
scavenged by the body’s white blood
cells.
• These foam cells are then deposited into
the lining of the artery wall.
• This process, known as atherosclerosis,
causes plaque deposits to enlarge, artery
walls to lose elasticity, and the passage
through the artery to narrow.
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A normal artery provides
open passage for blood
to circulate.
Plaques along an artery
wall narrow the passage
and obstruct blood flow.
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Eat Well Be Well: Nourish the
Heart Heading
1. Become a savvy supermarket
shopper.
2. Keep blood cholesterol at or
below the recommended levels.
3. Balance energy intake with
energy needs.
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Potato + 1 T butter + 1
T sour cream = 14 g
fat, 350 calories
A 3-oz. portion of lean
beef, chicken, or fish is
roughly the size of a
deck of playing cards or
the palm of the average
woman’s hand.
Potato + 2 T fat-free
sour cream + chives =
<1 g fat, 235 calories
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© 2007 Thomson - Wadsworth
The Trans Fatty Acid
Controversy
• Trans fatty acid: a
type of fatty acid
created when an
unsaturated fat is
hydrogenated.
 Found primarily in
margarines, shortenings,
commercial frying fats,
and baked goods.
 Trans fatty acids have
been implicated in
research as culprits in
heart disease.
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© 2007 Thomson - Wadsworth
Checking Out The Food Label
For Fat Information
• Total fat refers to all the fat in the food:
saturated, monounsaturated, polyunsaturated,
and trans fat.
• Total fat, saturated fat, trans fat and
cholesterol information are required on the
label.
• Listing the amount of monounsaturated and
polyunsaturated fats is voluntary.
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© 2007 Thomson - Wadsworth
© 2007 Thomson - Wadsworth
Bake, broil, poach, or
steam.
Choose Fats Sensibly…
• Cook and bake with a vegetable oil,
such as canola or olive oil, instead of
butter, shortening, or margarine
whenever possible.
• Try reducing fat in recipes a little at a
time and use nonstick sprays, fat-free
broth or wine in place of butter or
margarine.
• Refrigerate soups and broth, then
skim off the hardened fat.
• Prepare lean meats, trim visible fats,
remove poultry skin and cook meats
so that fats can drain off.
• Use herbs, spices, onions or garlic,
salsa , lemon juice or mustard instead
of butter, margarine or oil.
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Season with herbs &
spices.
• Phytochemicals
 physiologically
active compounds
found in plants
that appear to
help promote
health and reduce
risk for cancer,
heart disease, and
other conditions
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© 2007 Thomson - Wadsworth
Fat Can Be Healthy
• Use olive oil and other plant
oils that are rich in
monounsaturated and
polyunsaturated fats.
• Consume more omega-3 fats.
 Consider eating fish twice a week
as part of a balanced diet.
 Plant sources of omega-3 fats
include soybeans, flaxseed,
pecans and walnuts.
• Consume a diet that is lower
in saturated fat and higher in
complex carbohydrates and
fiber.
 Include more fruits, vegetables,
whole grain breads and other
grains and legumes.
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Fat Can Be Healthy
One place to find omega-3 fats is
fish, especially fatty fish like
salmon.
Nuts are rich in
many nutrients and
other beneficial
substances but are
also high in fat.
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Understanding Fat
Substitutes
Types of Fat-Replacer Ingredients
• Carbohydrate based:
 Carrageenan (a seaweed derivative),
 fruit purees,
 gelatin,
 gels derived from cellulose or starch,
 guar gum, xanthum gum,
 maltodextrins made from corn,
 corn starch (Stellar),
 polydextrose,
 Oatrim (made from oat fiber),
 and Z-trim (a modified form of insoluble
fiber).
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Understanding Fat
Substitutes
Types of Fat-Replacer Ingredients
• Protein based:
 Whey protein concentrate (Dairy-Lo),
 Microparticulated protein products
(Simplesse,® K-Blazer) made from whey,
 or milk and egg white protein.
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Understanding Fat
Substitutes
Types of Fat-Replacer Ingredients
• Fat based:
 Mono- and diglycerides;
 Caprenin—a substitute for cocoa butter in
candy— and Salatrim—found in reduced fat
baking chips—both containing long chain
fatty acids, which are partially absorbed,
and short-chain fatty acids— providing 5
calories per gram;
 Olestra (non-caloric artificial fat made from
fatty acids and sucrose).
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© 2007 Thomson - Wadsworth
Understanding Fat Substitutes
• Simplesse®: the trade name for a
protein-based, low-calorie artificial
fat, approved by the FDA for use in
foods such as frozen desserts; cannot
be used for frying or baking.
• Olestra: an artificial fat derived from
vegetable oils and sugar combined in
such a way that the body cannot
break them down. Sold under the
brand name Olean®, olestra does not
contribute calories to food.
 It can, however, prevent
absorption of some nutrients.
Thus, the FDA requires all
products made with it to be
fortified with fat-soluble vitamins.
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Diet and Heart Disease
• Eat a variety of antioxidant-rich fruits and
vegetables. Choose 5 or more daily.
• Choose fat-free or low-fat dairy products, such
as fat-free milk or low-fat or fat-free yogurt.
• Consume abundant legumes of many
varieties, including soybeans, kidney beans,
and lentils.
• Eat a variety of grains, including whole grains.
• Choose skinless poultry, lean meat, and fish,
especially omega-3 fatty-acid-rich fish such as
salmon.
• Limit intake of foods high in calories and low
in nutrition.
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Diet and Heart Disease
• Limit foods high in saturated fat, trans fat
and/or cholesterol, such as full-fat milk
products, fatty meats, tropical oils, partially
hydrogenated vegetable oils and egg yolks.
• Adopt low-fat cooking methods, such as
broiling, baking, steaming, braising, and stirfrying.
• Eat less than 6 grams of salt (sodium chloride)
per day (2400 milligrams of sodium).
• Consume alcohol only in moderation, if at all.
• Have no more than one alcoholic drink per day
(woman) or no more than two drinks per day
(man).
© 2007 Thomson - Wadsworth