Transcript C=C--C--C =C--C--C=C

Lipids
Lipids

Do not readily dissolve in water

Types of lipids:
– Triglycerides
– Phospholipids
– Sterols (Cholesterol)

Fats (solid) and oils (liquid)
– 9 kcal /gm
Chemical Forms of Common Lipids
Fatty Acids

Found in our body and foods
– In triglycerides

Saturated fatty acids
– Solid form

Unsaturated fatty acids
– Liquid form

Fats are composed of both saturated and
unsaturated fatty acids
Fatty Acid Structure
H H H H H H H H H H H H H H H HHO
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
Degree of saturation
alpha end
Saturated Fatty Acid Structure
H H H H H H H H H H H H H H H HHO
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
Degree of saturation: single carbon bond
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
omega end
alpha end
One double bond
Polyunsaturated Fatty Acid
Structure
H H H H H
H
H H H H H HH 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
> 2 double bonds
Composition of Common Fats / Oils
Essential Fatty Acids
Omega-3 fatty acid (alpha-linolenic acid)
 Omega-6 fatty acid (linoleic acid)
 Body can only make double bonds after
the 9th carbon from the omega end
 Functions

– Immune function, vision, cell membrane, and
production of hormone-like compounds
Triglycerides
Most common form of fats and oils in our
body & in the foods we eat
 Fatty acids attached to a glycerol

Triglycerides
Glycerol
+ 3 FA’s
Triglyceride +
3 H20
Phospholipids
Built on a glycerol backbone
 Contains phosphorus compound(s)
 Found in body
 Synthesized by the body as needed

Functions of Phospholipids
 Component
of cell membrane
 Emulsifier
– Bile acids
– Lecithins
– Improves food products

Found in wheat germ, peanuts, yolks,
soy beans, organ meat
Sterols
 Multi-ringed
structure
 Do not have a glycerol backbone
 Cholesterol is a sterol
 Waxy substance
 Do not readily dissolve in water
 Found in animal foods
Lipids in Foods
Hidden Fat
Look on the Nutrition Facts labels
 Look on the lists of ingredients
 Control portion size

Reduced-Fat Foods
Calorie content is about the same
 Sugar is commonly added in place of fat

Fat Substitutes

Water
– Diet margarine

Z-trim
– Starch derivative that binds with water

Fiber cellulose
– Maltrin, Stellar, Oatrim

Dairy-Lo
– Protein globules

Olestra or Olean (links fatty acid to sucrose)
– Not digested
– FDA approved for fried snack foods
– Fat-soluble vitamins issue
Hydrogenation of Fatty Acids
 Process
used to solidify an oil
 Addition of H to C=C double bonds
 Increases shelf life
 Formation of trans fatty acid
– (similar to shape of saturated fatty acid)
Excessive Trans Fatty Acid
Intake
 Raises
LDL
 Lowers HDL
 Increases risk for cardiovascular
disease
 Current intake is 3%-4% of total
kcal
 Added to food labels Jan. ‘06
Typical Sources of Trans Fat
Minimize Intake of Trans Fat
 Limit
use of hydrogenated fats
 Limit deep-fried foods
 Limit high-fat baked goods
 Limit use of non-dairy creamers
Absorption of Fat
95% of dietary fat is absorbed
 Diffused into the absorptive cells
 Short- and medium-chain (<12 C) fatty
acids

– Are water soluble
– Enter the portal system

Long-chain fatty acids re-form into
triglycerides
– Not water soluble
– Enter the lymphatic system
Carrying Fat in the Bloodstream
Water (blood) and oil (fat) are
incompatible
 Unique system of fat transportation is
needed

Transportation of Absorbed Fatty
Acids
 Re-formed
into triglycerides
 Packaged into chylomicrons
 Lipoprotein lipase
– Breaks down triglycerides in the
chylomicrons
 Chylomicron
remnant
– Delivered to the liver
Lipoproteins
Composition and Roles of
Lipoproteins
Transportation of Synthesized
Fat
Made primarily by the liver
 Very-Low-Density Lipoprotein (VLDL)
 Low-Density Lipoprotein (LDL)
 High-Density Lipoprotein (HDL)

Functions of Essential
Fatty Acids
Essential Fatty Acid- Omega-3
(alpha-linolenic acid)
H H H H H H H H H H H H H H H HH 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
Omega-3 Fatty Acid
 Primarily
from fish oil
 Also found in canola, walnuts, flax
seeds, mussels, crab, shrimp, and
soybean oil
 Recommended intake of ~2 servings
of fish per week
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
Omega-6 Fatty Acid
Found in vegetable oils
 Only need
~ 2-4 tablespoons a day

Health-related Effects
 Archidonic acid (Omega-6 )
– Increases blood clotting
– Increases inflammatory responses
 DHA, EPA (Omega-3)
– Decrease blood clotting
– Reduce heart attack
– Decrease inflammation
– Excess may cause hemorrhagic stroke
– Other possible uses: Lower triglycerides,
rheumatoid arthritis, behavioral disorders
Signs and Symptoms of
Essential Fatty Acids
Deficiency
Flaky, itchy skin
 Diarrhea
 Infections
 Retarded growth and wound healing

Functions of Fatty Acids
Provide energy
 Efficient storage of energy
 Insulation
 Protection
 Transport fat-soluble vitamins
 Some satiety
 Flavor and mouth feel

Recommendations for Fat Intake
No RDA
 AHA recommendations

– 20-30% of total kcal from fat
– 7-10% can come from saturated/trans fat
– 200-300 mg cholesterol/day

Average U.S. intake:
– 33% of total kcal from fat
– 13% of kcal from saturated fat
– 180-320 mg cholesterol/day
AHA Goals
AHA Recommendations
Other Recommendations
Fat intake can be higher as long as
saturated and trans fatty acid are minimal
 Eat plenty of fruits and vegetables
 Cut down on red meats
 Cut down on simple sugars and refined
carbohydrate
 Promote healthy weight
 Be active

Cutting the Fat