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