Chapter 5
The Lipids: Fats, Oils,
Phospholipids, and Sterols
Nutrition: Concepts & Controversies, 12e
Sizer/Whitney
Learning Objectives
 Discuss the reasons why a moderate intake
of lipids is an essential part of a healthy
diet.
 Compare and contrast the physical
properties and the sources of saturated,
polyunsaturated, and monounsaturated
fats.
Learning Objectives
 Describe how and where dietary lipids are
broken down and absorbed during
digestion and how they are transported
throughout the body.
 Describe the significance of the blood tests
for HDL and LDL cholesterol.
 Describe the roles of omega-3 and omega6 fatty acids in the body, and discuss which
may be too low in some people’s diets and
how they can increase their intakes.
Learning Objectives
 Justify the recommendation to eat fatty fish
instead of relying on fish oil supplements,
and discuss safety issues surrounding both
choices.
 Describe the information and structure of a
trans-fatty acid, and state ways in which
consumers may reduce their intakes.
Learning Objectives
 Develop a diet plan that provides enough of
the right kinds of fats within calorie limits.
 Discuss evidence for the benefits and
drawbacks of specific dietary fats in terms
of their potential effects on human health.
Introduction
 Diet moderate in fats
 Lipids are necessary and valuable
 Lipids can harm health
 Three classes of lipids
 Triglycerides
 Phospholipids
 Sterols
Usefulness of Fats in the Body
 Chief storage form of energy
 Provides most energy for body’s work
 Adipose tissue
 Secretes hormones
 Purposes of fat
 Shock absorbers, insulation, cell
membranes
 Fat-soluble substances
A Fat Cell
Usefulness of Fats in Food
 People naturally
like high-fat foods
 Aromas
 Flavors
 Tenderness
 Satiety
Triglycerides: Fatty Acids and
Glycerol
 Triglycerides
 Glycerol backbone
 Three fatty acids
 Fatty acid
differences
 Chain length
 Saturation
 Animal species
make triglycerides
Saturated Versus Unsaturated
Fatty Acids
 Saturation
 Hydrogen atoms
 Levels of saturation
 Saturated
 Unsaturated
 Polyunsaturated
 Monounsaturated
Three Types of Fatty Acids
Saturated Versus Unsaturated
Fatty Acids
 Melting point
 More unsaturated,
more liquid
 Fat hardness
 Softer generally is
healthier
 Sources of fatty
acids
 Heart disease
Fatty Acid Composition of
Common Food Fats
Phospholipids and Sterols
 Phospholipids
 Glycerol, two fatty acids, and a phosphorus
molecule
 Soluble in water and fat
 Emulsifier
 Sterols
 Roles in the body
 Plant sterols
Digestion and Absorption of Fats
 Digestion
 Stomach
 Small intestine
 Bile
 Pancreas
Digestion and Absorption of Fats
 Absorption
 Fatty acids split from glycerol
 Fatty acids, phospholipids, and
monoglycerides
 Bile shuttles lipids across mucus layer
 Efficiency of absorption process
 Speed of digestion
The Process of Lipid Digestion
and Absorption
Transport of Fats
 Glycerol and shorter-chain fatty acids
 Bloodstream
 Larger lipids
 Protein carriers
 Released into lymph
 Chylomicrons
Storing and Using the Body’s Fat
 Body conserves fat molecules
 Fat depots
 Excess carbohydrate
 Call for energy
 Dismantle stored triglycerides
 Release fatty acids into blood
 Carbohydrate’s role
 How to use more fat for energy…
Glucose to Fat
Dietary Fat, Cholesterol, and
Health
 Heart and artery disease
 Saturated and trans fats
 Beneficial fats
 Cancer
 Diet high in saturated fats
 Obesity
 Overconsumption of calories
Recommendations for Lipid
Intakes
 Some fat in the diet is essential
 Healthy range of fat intakes
 DRI
 20 to 35 percent of daily energy
 Fats to keep low
 Essential fatty acids
Lipoproteins and Heart Disease
Risk
 Lipoprotein movement in the body
 Liver
 Types of lipoproteins
 Chylomicrons
 Very-low-density lipoproteins (VLDL)
 Low-density lipoproteins (LDL)
 High-density lipoproteins (HDL)
Lipoproteins
Lipoproteins and Heart Disease
Risk
 LDL and HDL
difference
 Size and density
 Delivery and
scavenging
 Inflammation
 Heart attack risk
 Oxidation of LDL
 Phytochemicals
Food Cholesterol and Blood
Cholesterol
 Saturated and trans fats
 CVD risk indicators
 Dietary cholesterol
 Genetic inheritance
 Moderation is key
Recommendations Applied
 Heart disease
 Leading cause of death among Americans
 Lower LDL
 Dietary tactics
 Trim saturated and trans fats from diet
 Raise HDL
 Physical activity
 Benefits for heart health
Food Fat, Saturated Fat, and
Calories
Top Contributors of Saturated
Fats to the U.S. Diet
The Need for Essential Fatty
Acids
 Essential fatty acids
 Linoleic acid and
linolenic acid
 Functions
 Eicosanoids
 DRI recommendations
 Deficiencies
Omega-6 and Omega-3 Fatty
Acid Families
 Linoleic
 Omega-6 fatty acid
 Arachidonic acid
 Linolenic acid
 Omega-3 fatty acid
 DHA and EPA
 Heart disease
 Brain function and vision
 Inflammation
Fish Oil Intakes and
Cardiovascular Death Rates
Recommendations for Omega-3
Fatty Acid Intake
 Competition for metabolic enzymes
 Consumption levels
 Lacking omega-3 fatty acids
 Fish oil supplements
 Health concerns with fish oil supplements
 Omega-3 enriched foods
 Flaxseed
Food Sources of Omega-6 and
Omega-3 Fatty Acids
Seafood Safety – Balancing Risks
and Benefits
 Safe consumption levels
 Mercury
 Methylmercury
 Damage to the body
 Cooking methods of fish
 Benefits outweigh risks
Mercury in Fish Species
Effects of Processing on
Unsaturated Fats
 Hydrogenation
 Effects on fats
 Oxidation of unsaturated oils
 Hydrogenation of oils
 Benefits of hydrogenation
 Nutrient losses
 Alternatives to hydrogenation
Hydrogenation Yields Both
Saturated and Trans-Fatty Acids
Effects of Processing on
Unsaturated Fats
 Trans-fatty acids
 Polyunsaturated fats
 Change in chemical structure
 Health effects
 LDL and HDL cholesterol
 Similarities with saturated fat
 Trans fat in foods
Fat in the Diet
 Essential fat
 20% of calories from unsaturated fats
 Visible vs. invisible fat
 Added fats
 Majority are invisible fats
Fat in the Diet
 Meat, poultry, fish, dried peas & beans,
eggs, & nuts
 Four categories for meat
 Limit intake to 5 to 7 ounces per day
 Choosing low-fat meats
 Ground turkey or chicken vs. beef
 Milk, yogurt, and cheese
 Foods not included in this category
 Grains
Calories, Fat, and Saturated Fat
in Cooked Ground Meat Patties
Lipids in Milk, Yogurt, and Cheese
Lipids in Bread, Cereal, Rice, and
Pasta
Defensive Dining
 Portion sizes
 In the grocery stores
 Fat replacers & artificial fats
 Olestra
 “Fat-free” options
 Cooking at home
Substitute Ingredients to Lower
Saturated Fat Intakes
Defensive Dining
 Use flavorful fats
 Choose unsaturated oils
 Revamp recipes
 Suggestions
 Find lower-fat fast foods
 Change your habits
Good Fats and Bad Fats –
Which are Which?
Controversy 5
Objectives to “Low-Fat”
Guidelines
 Problems with low-fat diets
 Groups who benefit from low-fat diets
 Mediterranean-type diets
 New guidelines
 Up to 35 percent of total calories
High-Fat Foods and Heart Health
 Olive oil
 Potential health
benefits
 Darker the better
(extra virgin)
 Canola oil
High-Fat Foods and Heart Health
 Mediterranean diet
 Whole foods
 Dietary focus
 Fish
 Nuts
 Walnuts
 Almonds
 Potential benefits
High-Fat Foods and Heart Health
 Butter or margarine
 Read labels
 Low saturated fat and trans fat levels
 Plant-enriched margarines
 Drawbacks
 Fats to avoid
 Choose carefully among high-fat foods
Impact of Change in Saturated Fatty
Acid Intake on Blood LDL Cholesterol
and Heart Disease Risk