Download Nutrition Chapter 4 Lipids

Fats and Oils
Chapter 4
Learning Objectives






Define lipids, triglycerides, fats, and oils, and describe the
roles fat plays in food.
Identify foods high and low in fat, and define saturated,
monounsaturated, and polyunsaturated fats and list foods in
which each one is found.
Describe trans fatty acids and give examples of foods in
which they are found.
Identify the two essential fatty acids, list their functions in
the body, and give examples of foods in which they are
found.
Explain what EPA and DHA do in the body, and what foods
they are found in.
Define cholesterol, list three of its functions in the body, and
give examples of foods in which it is found.
Learning Objectives







List four functions of fat.
Discuss fat digestion, define lipoprotein, and distinguish
between chylomicron, low-density lipoprotein, and highdensity lipoprotein.
State recommendations for dietary intake of fat, saturated fat,
trans fat, monounsaturated fat, polyunsaturated fat, and
cholesterol.
Distinguish between the percentage of fat by weight and the
percentage of kcalories from fat.
Discuss the relationship between fat intake and heart disease
and cancer.
Discuss the nutrition and uses of milk, dairy products, and
eggs on the menu.
Select fats and oils appropriately for cooking and baking.
Introduction to Fats and Oils

Lipid is the chemical
name for a group of
compounds that
includes:
◦ Fats: Solid at room
temperature usually from
animal sources
◦ Oils: Liquid at room
temperature usually from
plant sources
◦ Cholesterol: found in the
body
◦ Lecithin: emulsifier
In foods, fat:







Enhances taste and aroma
Adds crispness to fried foods
Makes meats juicy and tender
Makes baked goods tender
Carries flavors such as in an Indian curry
Provides a smooth texture and creamy
mouthfeel
Makes food yummy!
Triglycerides
Most of the lipids in
foods AND most
of the lipids in the
human body are in
the form of:
Triglycerides,
made up of three
fatty acids attached
to a backbone
Types of Triglycerides

Saturated fat: “bad fat”
A triglyceride in which the maximum number of
hydrogen atoms are attached to every carbon atom—
thus, the fat is “saturated” with hydrogen atoms.

Monounsaturated fat: “decent fat”
A triglyceride in which most of the fatty acids are
monounsaturated—one fatty acid is missing a pair of
hydrogen atoms in the middle.
 Polyunsaturated fat: “good fat”
A triglyceride in which most of the fatty acids are
polyunsaturated—several hydrogen atom pairs are
missing.
 All food contains a mixture of saturated and unsaturated
fats
Triglycerides in Foods
Fats have a “bad boy” reputation that is not
entirely deserved.
 The problem with fats has more to do with the
TYPE of fat you eat rather than the
QUANTITY.
 Most Americans need to replace saturated fat
with monounsaturated and polyunsaturated fat
to decrease heart disease risk.

Fat in Various Food Groups
Low to No Fat
 Fruits and veggies
(except avocado,
olives, coconuts,
fried veggies)
 Breads, cereal, rice,
pasta, grains (except
croissant, biscuit,
cornbread, granola)
 Dry beans and peas




Higher in Fat
Fats/oils/condiments
Meat/poultry/fish:
Chicken w/o skin and
many fish are quite
low in fat. Eggs.
Dairy: Regular dairy
foods are high in fat.
Nuts and seeds
You can’t see most of the fat you get in the foods you eat.
All food fats contain a mixture of saturated and unsaturated fat.
Foods High in Saturated Fat

Mostly animals foods
◦ Beef, pork (sausage, franks,
bacon)
◦ Grains-based desserts such as
cookies (made with fat and
eggs
◦ Whole milk and dairy products
made with whole milk such as
many cheeses and ice cream
◦ French fries and other fried
foods
◦ Eggs, poultry skin
◦ Also tropical oils: coconut,
palm kernel, and palm oils
These fats contribute to heart disease.
Foods High in Monounsaturated Fat








Olive oil
Canola oil
Safflower oil
Sesame oil
Avocado
Nuts and seeds
Peanut butter
Tofu
Foods High in Polyunsaturated Fat





Corn oil
Soybean oil
Sunflower oil
Nuts and seeds
Fatty fish
Trans Fats
Occur naturally at low levels in meat and dairy
 Keep your intake as low as possible.
 Trans fats are created when vegetable oils
undergo hydrogenation
◦ Liquid oils are converted to solid fats for
stabilization
 Margarine, some fry oil, shortening
◦ Hydrogen is added to tighten up chemical
structure

Hydrogenation
Vegetable
Oils
Hydrogenation
Shortening
Margarine
Hydrogenation produces trans fatty acids, and
also changes some unsaturated fatty acids to
saturated fatty acids.
 Hydrogenation helps products stay fresh longer
and gives them a higher smoking point and
makes them spreadable

What foods contain trans fats?

Trans fats can be found in some:
◦ Fried foods like french fries and doughnuts
◦ Baked goods including pastries and cookies
◦ Pie crusts and biscuits
◦ Ready-made frosting
◦ Microwave popcorn
◦ Stick margarines and shortenings
Use the Nutrition Facts label—
trans fat must be listed.
Essential Fatty Acids

The body can make all of the fatty acids that it
needs except for two:
◦ Linoleic acid (omega-6 fatty acid)
◦ Alpha-linolenic acid (ALA) (omega-3 fatty
acid)
Foods with Linoleic Acid (omega-6)
Vegetable oils such as:
◦ soybean
◦ corn
◦ sunflower
 Margarine and salad dressings with vegetable
oils
 Whole grains and vegetables also supply some
linoleic acid (and ALA)
 Americans have no issue with getting plenty of
Linoleic Acid

Foods with ALA (omega-3)






Several vegetable oils:
◦ Canola
◦ Flaxseed
◦ Walnut
Walnuts
Ground flaxseed
Soy products
Fatty fish
Americans do not get enough ALA
Functions of Essential Fatty Acids
(Linoleic acid and alpha-linolenic acid)
Part of cell membranes
 Play a role in the proper functioning of the
immune system
 Vital to normal growth and cognitive
development in infants and children

There are two more omega-3 fatty
acids that are heart healthy:
Docosahexaenoic acid (DHA)
 Eicosapentaenoic acid (EPA)
 Soon there will likely be DRIs for DHA and
EPA.

Foods with DHA and EPA
Fatty fish such as:
◦ Salmon, mackerel,
sardines, halibut,
bluefish, trout, tuna
 Lean fish (such as
haddock, cod,
flounder) contain
only small amounts
of DHA and EPA

The fatty fish are excellent sources of DHA & EPA.
ALA is found in flaxseeds, flaxseed oil, walnut oil, canola oil, and walnuts.
Functions of DHA and EPA
DHA is important for proper brain and eye
development during pregnancy and infancy.
 DHA and EPA are excellent for keeping your
heart healthy. They:
◦ Reduce blood pressure
◦ Reduce heart rate
◦ Reduce blood triglyceride levels
◦ Reduce blood clots (which can start heart
attacks)

Most Americans get PLENTY of omega-6
fatty acids—but NOT enough omega-3s.
So…
 Eat about 8 ounces per week of a variety of
seafood to provide an average of 250 mg per
day of EPA and DHA.
Taking in at least 250 mg per day of
EPA and DHA is associated with
preventing deaths from heart
disease and heart disease itself.
Mercury
Nearly all fish and shellfish contain traces of
mercury.
 This is a concern for pregnant women, women
who may become pregnant, nursing mothers,
and young children who need to avoid certain
fish.

Cholesterol
Cholesterol is a soft waxy substances found only
in animal foods.
 Cholesterol is needed to maintain cell
membranes and is in every cell in your body.
 Cholesterol is needed to make:
◦ Bile acids
◦ Many hormones such as estrogen, cortisone
◦ Vitamin D

Cholesterol is only in animal foods:





Egg yolks
Meat
Poultry
Milk and milk
products (it is lower
in lower-fat and
nonfat products)
Fish (shrimp is
higher than other Eggs, meat, and whole milk provide
most of the cholesterol we eat (and
fish)
these are high in saturated fat too).
Cholesterol





The body makes some cholesterol daily.
Recommended intake from food: limit to 300
mg daily—about 4 oz. of meat, poultry, or fish
contain 100 mg cholesterol.
One egg has 186 mg.
Men tend to take in more cholesterol than
recommended.
Cholesterol in your blood builds up in your
arteries and is a risk factor for heart disease.
Functions of Lipids
About 13 to 30 percent of your weight is fat.
 Fat is part of all the cells in your body—
provides energy (9 kcal/gram).
 Fat under the skin provides:
◦ Insulation—maintains body temperature
◦ Cushion—keeps critical organs safe
 Extra energy is stored in the body as fat
◦ Adipose cells – compact energy storage
 Able to swell to 20x their size
 We can create as many adipose cells as
needed, but cannot get rid of the ones we use

Functions
Fat is an important part of all cell membranes.
 Fat transports fat-soluble vitamins in body.
 Certain fat-containing foods provide the body
with the essential fatty acids—needed for
normal growth and development, immune
system, and maintain cell membranes.

Digestion, Absorption, and
Metabolism
Fats are hard for the body to digest and absorb
because triglycerides and water don’t mix.
◦ Fat is the last nutrient the body digests
 Minimal digestion of fats occurs before they
reach the small intestine.
◦ Salivary enzymes pre-digest some, but not to
an applicable degree

Digestion and Absorption
When fats reach the small intestine, the
gallbladder releases bile into the intestine.
 Bile acids emulsify fat—split fat into small
pieces—to allow enzymes to break down
triglycerides into its fatty acids.
 Then the fatty acids are absorbed into the
intestinal wall, where triglycerides are reformed.

Lipoprotein

Lipoproteins contain varying amounts of:
◦ Fats
◦ Protein
◦ Cholesterol
Lipoproteins carry triglycerides around the
body because their protein and
phospholipids make them water soluble.
Other Lipoproteins

These lipoproteins are responsible for carrying
cholesterol around the body.
◦ Low-density lipoprotein (LDL)—carries
cholesterol to the body’s cells, called the
“bad” cholesterol because the higher the level
in your blood, the greater your risk for heart
disease.
◦ High-density lipoprotein (HDL)—“good
cholesterol”—picks up cholesterol from the
cells and takes it to the liver for removal.
Phospholipid - Lecithin






Contains a phosphate group in place of one fatty
acid
Soluble in fat and water
Used primarily in the industry as emulsifiers –
substances capable of breaking up fat into small
droplets to create a uniform mixture that wont
separate
In the body, lecithin helps keep the blood uniform to
flow through the body. Also a big component of cell
membranes
Egg yolks are rich in lecithin
Our liver makes enough lecithin so it is not
considered an essential nutrient
Dietary Recommendations
Acceptable Macronutrient Distribution Ranges
◦ Over 18 years old 20 to 35 percent of
kcalories
 Americans tend to eat too much saturated and
trans fat and not enough omega-3s

Dietary Recommendations





Consume less than 10 percent of kcalories from
saturated fat by replacing it with mono- and
polyunsaturated fat.
Consume less than 300 mg/day of cholesterol.
Keep trans fatty acid consumption as low as
possible by limiting synthetic sources.
Replace protein foods that are high in saturated
fats with choices lower in solid fat.
Use oils to replace solid fats when possible.
What does 96% fat free mean?
96 percent of the weight is lean or without fat.
 Only 4 percent of its weight is actually fat.
 It does not tell you anything about how many
kcalories it has.

Percent of Kcalories from Fat

Percentage of
kcalories from fat
tells you what
percent of the total
kcalories come from
fat.
Fats and Health

Heart Disease
◦ Number one killer for US men and women.
◦ Many Americans have high blood cholesterol and
high blood pressure.
◦ Too much circulating cholesterol builds up in the
walls of the arteries—especially the heart’s
arteries—which leads to plaque accumulation.
Heart Attack and Stroke
Heart attack occurs when the flow of blood to a
section of the heart muscle suddenly becomes
blocked.
 Stroke occurs when the blood supply to part of
the brain is cut off.

If deprived of blood for more
than a few minutes, parts of the
heart and brain can die.
What are additional risk factors
for heart disease?






Age
Heredity
Smoking
High blood pressure
Diabetes mellitus
Obesity
Cancer
Cancer is the second leading cause of death in
the United States.
 Diets high in processed meats and/or red meats
and obesity have been linked with a higher risk
of colon cancer.
 Weight gain during adulthood and obesity is
linked with a higher risk of breast cancer after
menopause
 Being overweight or obese is clearly linked to
cancer of uterus, esophagus, and kidney.
