Lipids
Reading: Chapter 5
Why Does a Body Need Fat?
Chief storage form of energy
Insulator
Pads and protects the body from mechanical shock
Component of cell wall
Nervous system primary structure
Precursor of hormones, bile salts, Vitamin D
Feeling of fullness "satiety"
Why Have Fats in Foods?
Provides flavor, texture, palatability
Concentrated source of calories
Source of fat-soluble vitamins and essential fatty acids
The Lipid Family
Triglycerides
Phospholipids
Sterols
Role of Triglycerides in the Body
Energy
Insulation and Shock Absorber
Protein Sparing
Satiety--fullness
Triglyceride Structure
What Makes a Triglyceride Unique?
Fatty Acid Structure
Two Classes of Essential Fatty Acids
“The Omega-3 Class”
Linolenic (18:3)
•Food Sources:
•Soybeans, nuts and seeds
Eicosapentaenoic (EPA) (20:5)
Docosahexaenoic (DHA) (20:6)
“The Omega-6 Class”
Linoleic acid (18:2)
Food source:
Arachidonic acid (20:4)
Food source:
Functions of Essential Fatty Acids
1.
2.
3.Effects on Heart disease, High blood pressure
Phospholipids
Produced by the liver
Nonessential in the diet
Chemical structure different from triglycerides
Lethicin:
Role/Function of Phospholipids: Movement of fat-soluble vitamins and hormones in and out of cells
Emulsifier
Sterols
Complex, multi-ring structure
Manufactured by the liver
Secreted in bile
Nonessential
Part of cell membranes
Food Sources:
Triglyceride Digestion:
How Does Body Transport Lipids in Blood?
Lipoproteins—packages
•All lipids in center
•Protein on outside
Lipoproteins:
1.
2.
3.
4.
Lipoproteins Compared
Blood Tests and Lipoproteins
Desirable Total blood cholesterol
Desirable LDL cholesterol
Desirable HDL cholesterol
Desirable Triglycerides
Dietary Fats Affect Blood Cholesterol Levels
Saturated fats and Trans Fats:
lMonounsaturated Fats:
Polyunsaturated Fats:
Omega 3 Fatty Acids:
Other Factors that Decrease Blood Cholesterol Levels
Hydrogenation Changes the Shape of Fatty Acids
Advantages of Hydrogenation
Increases shelf-life
Changes the texture
Inexpensive process
Disadvantages of Hydrogenation
Increases the amount of saturated fat in food
Trans fatty acids increase blood cholesterol levels
Sources of Hydrogenated, Trans Fats
Margarines (stick, tub)
Commercially prepared baked goods
Chips
Peanut butter with hydrogenated oils
Fried foods
Should You Eat Margarine or Butter?
MARGARINE-1 T.
Total fat=
Saturated fat=
Trans fat=
Kcals=?
BUTTER-1 T.
Total fat=
Saturated fat=
Trans fat=
Kcals=?
Dietary Recommendations for Fat in the Diet
% of total calories from fat
% of total calories from saturated fat
% of fat calories should be essential fatty acids
mg cholesterol per day