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Chapter 4
Lipids: Fats and Oils
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Lipids
 Fats
 Oils
 Cholesterol
 Lecithin
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Functions of Lipids
 Insulation
 Cushion around critical organs
 Provides energy (adipose cells = compact
energy storage)
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Protein-sparing
Part of all cell membranes
Transport of fat-soluble vitamins
Essential fatty acids
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In food, fat enhances:
 Taste
 Smooth texture
 Flavor
 Creamy feeling
 Aroma
 Feeling full
 Crispness
 Juiciness
 Tenderness
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Triglycerides
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Types of Fatty Acids
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Triglycerides in Food
 Fruits and vegetables
 Breads, cereals, rice, pasta, and grains
 Dry beans and peas, nuts and seeds
 Meat, poultry, fish
 Dairy foods
 Fats, oils, and condiments
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3 Types of Triglycerides
1. Saturated triglycerides
(saturated fat)
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ANIMAL FOODS
 Cheese
 Beef
 Whole milk
 Fats in baked goods
 Butter
 Margarine
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3 Types of Triglycerides
 2. Monounsaturated
Fats
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Olive oil
Canola oil
Peanut oil
Margarine made with
canola oil or other
highly
monounsaturated fat
Olive Oil
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3 Types of Triglycerides
3.
Polyunsaturated Fats
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Safflower oil
Corn oil
Soybean oil
Sesame oil
Sunflower oil
Nuts and seeds
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Trans Fatty Acids
 Occur naturally at low levels in meat and
dairy foods.
 Trans fats we eat are often due to
hydrogenation of vegetable oils to make
shortening, margarine, and fats for frying.
 Trans fats raise blood cholesterol levels as
much as saturated fat.
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Main Contributors to
Trans Fats in Diet
 Cakes, cookies, pies, bread, etc. 40% of
trans fats eaten
 Animal products
21%
 Margarine
17%
 Fried potatoes
8%
 Potato chips, corn chips, popcorn
5%
 Household shortening
4%
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Essential Fatty Acids
 Linoleic acid is an omega-6 fatty acid found in
vegetable oils, whole grains, and vegetables.
 Alpha-linolenic acid is the leading omega-3 fatty acid
found in food, and it is found in canola, flaxseed,
soybean, walnut, and wheat germ oils. Other good
sources include ground flaxseed, walnuts, and soy
products.
 The body converts alpha-linolenic into DHA and EPA
(also omega-3s). DHA and EPA are found in fatty
fish such as salmon and mackerel.
 Americans get more than enough linoleic, but not
enough alpha-linolenic.
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Essential Fatty Acids (cont’d)
 Both EFAs:
 Are vital to normal growth and development in infants
and children,
 Maintain the structural parts of cell membranes
 Have a role in the proper functioning of the immune
system
 Are used to make eicosanoids.
 Eicosanoids made from linoleic acid tend to increase
blood pressure, blood clotting, and inflammation.
 Eicosanoids made from alpha-linolenic acid dilate
blood vessels and reduce blood clotting and
inflammation.
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Rancidity
 Deterioration of fat, resulting in undesirable
flavors and odors.
 Saturated fats are more resistant to rancidity
than unsaturated fats.
 Rancidity is hastened by heat and ultraviolet
light.
 To prevent rancidity, store fats and oils tightly
sealed in cool, dark places.
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Cholesterol
 An odorless, white, waxy, powdery
substance.
 Cholesterol is present in every cell in your
body. It is needed to make bile acids, to make
cell membranes, many hormones (such as
sex hormones), and vitamin D.
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Cholesterol (cont’d)
 Cholesterol is found only in
foods of animal origin: egg
yolks, meat, organ meats,
poultry, fish, milk, and milk
products. Lower-fat milk
products contain less
cholesterol than full-fat milk
products.
 We take in about 200 to 400
milligrams of cholesterol
daily and the liver and body
cells also make cholesterol
(about 700 milligrams),
therefore it is not an
essential nutrient.
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Lecithin
 A phospholipid.
 Functions as a vital component of cell
membranes.
 Also acts as an emulsifier.
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Digestion, Absorption, & Metabolism
 Mouth – Lingual lipase.
 Stomach – Gastric lipase.
 Intestine
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Bile acids
Pancreatic lipase
Intestinal lipase
 Once absorbed, triglycerides are reformed.
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Lipoproteins
Protein-coated packages that carry fat and
cholesterol through the bloodstream.
Chylomicron
Very low-density lipoprotein
(VLDL)
Low-density lipoprotein
(LDL)
High-density lipoprotein
(HDL)
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Lipids and Health
 Heart disease
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Too much circulating cholesterol leads to
plaque and atherosclerosis
Angina
Myocardial infarction
Stroke
 Main source of cholesterol buildup: LDL
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Lipids and Health (cont’d.)
 What affects cholesterol levels?
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Saturated fat, trans fat, and cholesterol in diet
Mono- and polyunsaturated fat in diet
Weight
Physical activity
Age and gender
Heredity
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Lipids and Cancer
 Cancer is the second leading cause of death
in the U.S.
 Fat may be involved in certain cancers such
as prostate cancer.
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Dietary Recommendations for Fat
 No RDA or AI for total fat (except for infants),
saturated fat, cholesterol, or trans fats.
 AMDR for total fat
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1–3 years old
4–18 years old
Over 18 years old
30-40% of kcal
25-35% of kcal
20-35% of kcal
 AI set for essential fatty acids.
 DGA and AHA recommend 10% or less from sat. fat,
less than 300 mg of cholesterol daily, and replace sat
fats with poly and mono fats such as fish and nuts.
 If fat intake is higher than 30%, use
monounsaturates.
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Percentage of Kcal From Fat &
Percentage of Fat By Weight
 Percentage of kcalories from fat
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27 kcal from fat x 100 = 19 percent
140 kcal
 Percentage of fat by weight
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Ingredient Focus: Milk, Dairy & Eggs
 Milk
 Cheese
 Eggs
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Fat Substitutes
 Water
 Carbohydrate-based
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Cellulose gel
Carrageenan
Polydextrose
Starch
Modified food starch
Dextrins and maltodextrins
Gums
 Protein-based – Simplesse
 Fat-based – Olestra
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Copyright ©2007 John Wiley & Sons, Inc.
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