1. Chapter 5:
Lipids

2. Overview
 Structure: Saturated vs non-saturated FA
 Classification: Essential vs non-essential
 Classes: TG, phospholipids, sterols
 Functions
 Digestion and absorption
 Transport
 Foods and diet patterns

3. Lipids
 Do not readily dissolve in water
 Fats are solid at room temperature
 Oils are liquid at room temperature
 Triglycerides are the main form of lipids in
food and body (storage)
 Energy dense (9 kcal /gm)

4. Fatty Acids
 Building blocks of lipids
 Saturated
 Unsaturated
 Monounsaturated
 Polyunsaturated

5. Fatty Acid Structure
H H H H H H H H H H H H H H H H H O
H-C--C--C--C--C--C--C--C--C--C--C--C--C--C--C--C--C--C-OH
H H H H H H H H H H H H H H H H H
Methyl group Acid group
(omega end) (alpha end)
degree of saturation

6. Saturated Fatty Acid Structure
H H H H H H H H H H H H H H H H H O
H-C--C--C--C--C--C--C--C--C--C--C--C--C--C--C--C--C--C-OH
H H H H H H H H H H H H H H H H H
Methyl group Acid group
(omega end) (alpha end)
Saturated Fatty Acid C18:0

7. Monounsaturated Fatty Acid
Structure
H H H H H H H H H H H H H H H O
H-C--C--C--C--C--C--C--C--C=C--C--C--C--C--C--C--C--C-OH
H H H H H H H H H H H H H H H H H
Methyl group Acid group
(omega end) (alpha end)
One double bond C18:1

8. Polyunsaturated Fatty Acid
Structure
H H H H H H H H H H H H H O
H-C--C--C--C--C--C=C--C--C=C--C--C--C--C--C--C--C--C-OH
H H H H H H H H H H H H H H H H H
Methyl group Acid group
(omega end) (alpha end)
> 2 double bonds C18:2

9. Chain Length & Saturation:
Fatty Acid Characteristics
 Long chain…> 12 C
 Medium chain …6-10 C
 Short chain…< 6 C
 Saturated
 Unsaturated

10. Unsaturated Fats
 Fewer H atoms; double bonds between Carbons
 Usually liquid at room temp
 Mostly plant and fish sources
 More chemically active (turn rancid faster)
 Lower blood cholesterol
 Monounsaturated fat (MUF) - 1 double bond
(minus 2 H)
 Polyunsaturated fat (PUF) - 2 or more double
bonds

11. Saturated Fats
 Maximum # of Hydrogen atoms
 Usually solid at room temp.
 Mostly from animal sources (meat & dairy)
 Exceptions - tropical oils (palm, coconut)
very saturated
 Raise blood cholesterol

12. Essential Fatty Acids
 Cannot be produced by the body
 Omega-3 & Omega-6 fatty acids
 Essential for immune function, vision, cell
membrane, and production of hormone-like
compounds

13. Essential Fatty Acid- Omega-3 (alpha-linolenic
acid)
H H H H H H H H H H H H H H H H H O
H-C--C--C=C--C--C =C--C--C=C--C--C--C--C--C--C--C--C-OH
H H H H H H H H H H H
omega end alpha end
1st double bond is located on the 3rd carbon
from the omega end

14. Omega-3 Fatty Acid
 Fish oil is important source
 Also found in canola, soybean oil & nuts
 Eicosapentaenoic acid (EPA) and
docosahexaenoic acid (DHA)
 Recommendation: eat fish 2 x per week
 Decreases blood clot formation
 Lowers risk of heart disease

15. Essential Fatty Acid- Omega-6
(alpha-linoleic acid)
H H H H H H H H H H H H H O
H-C--C--C--C-- C--C =C--C--C=C--C--C--C--C--C--C--C--C-OH
H H H H H H H H H H H H H H H H H
omega end alpha end
1st double bond is located on the 6th carbon
from the omega end

16. Omega-6 Fatty Acid
 Found in vegetable oils
 Arachidonic acid
 Need about 1 tablespoon daily
 Increases blood clotting
 Increases inflammatory responses

17. Signs and Symptoms of Essential
Fatty Acids Deficiency
 Flaky, itchy skin
 Diarrhea
 Infections
 Growth retardation
 Poor wound healing
 Anemia

18. Functions of Lipids
 Concentrated energy (diet and storage)
 Provides essential FAs
 Insulation for body
 Padding around organs
 Transport fat-soluble vitamins
 Contribute to satiety
 Flavor and mouth feel of foods
 Present in cell membranes

19. Triglycerides (TGs)
 Most lipids in foods and body in form of
TGs (95%)
 Chemical structure:
 Glycerol back bone
 3 fatty acids (Fas)
 FA 4-22 C long; usually 16-20 C

20. Triglycerides
(condensation reaction)
Glycerol + 3 FA’s Triglyceride +
3 H20
H O
H--C--O--C--
O
H--C--O--C--
O
H--C--O--C--
H
Fatty Acid
Fatty Acid
Fatty Acid
+
H O
H--C--O--C--
O
H--C--O--C--
O
H--C--O--C--
H
Fatty Acid
Fatty Acid
Fatty Acid

21. Triglycerides

22. Function of Triglycerides
 Concentrated energy (diet and main storage form)
 Provides essential fatty acids (linoleic; linolenic)
 Carrier of Fat Soluble Vits (A,D,E,K)
 Body Insulation & padding around organs
 Cell membranes
 Adds flavor & texture to foods
 Contributes to satiety

23. Phospholipids
 Built on glycerol backbone
 > 1 FA replaced with P containing
compound
 Cell membranes
 Help transport other fats in blood
 Emulsifier in foods
 Mix with both water and fat

24. Chemical forms of Phospholipid

25. Sterols
 Multi-ringed structures; noncaloric
 Do not dissolve in water well
 ex. cholesterol & Vitamin D

26. Two sterols

27. Function of Cholesterol
 Cell membranes
 Precursor for Vit D & some hormones (estrogen,
testosterone)
 Major component of bile
 ONLY FOUND IN ANIMALS; NEVER FOUND
IN PLANTS
 Not an essential nutrient since it’s made in body
 Produced by the liver

28. Cell membranes