Download Essential Fatty Acid

Chap. 5: Lipids
Properties of Lipids
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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)
Unsaturated Fatty Acids
Saturated Fatty Acids
Essential Fatty Acids
Energy dense (9 kcal /gm)
Fatty Acid Structure
(Fig. 5-1-A)
omega end
degree of saturation
alpha end
Saturated Fatty Acid Structure
(Fig. 5-1-A)
omega end
alpha end
degree of saturation: single carbon bond
Monounsaturated Fatty Acid Structure
omega end
alpha end
One double bond
Polyunsaturated Fatty Acid Structure
omega end
(Fig. 5-1-B)
> 2 double bonds
(Fig. 5-1-C)
alpha end
Essential Fatty Acids
 Body
can only make double bonds after the 9th carbon
from the omega end
 Needed
for immune function, vision, cell membrane, and
production of hormone-like compounds
Essential Fatty Acid- Omega-3 (alpha-linolenic acid)
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 or soybean oil
 Recommend intake of ~2 servings of fish per week
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Essential Fatty Acid- Omega-6 (alpha-linoleic acid)
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
tablespoon a day
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~1
Essential Fatty Acids
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The Different Effects
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Archidonic acid (Omega-6 )
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increase blood cot
increase inflammatory responses
DHA, EPA (Omega-3)
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decrease blood clotting
reduces heart attack
excess may cause hemorrhagic stroke
large amounts may decrease inflammation pain with rheumatoid arthritis
Signs and Symptoms of Essential Fatty Acids
Deficiency
Flaky, itchy skin
 Diarrhea
 Infections
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Retarded growth and wound healing
 Anemia
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Triglycerides
Glycerol
+
3 FA’s
Triglyceride +
3 H 20
(Ester bond)
Triglycerides
esterification
desterfication
Phospholipid
Built on a glycerol backbone
 Has at least one fatty acid replaced with phosphorus compound
 Found in body
 Synthesized by the body as needed
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Functions of Phospholipids
 Make
up cell membrane
 Emulsifier
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Bile acids
Lecithins
Improves food products
Emulsifier
Hydrophilic end (attracts water)
Hydrophobic end (attracts lipid)
Emulsification
Cholesterol
A
multi-ringed structure
 Do not have a glycerol backbone
 Waxy substance
 Do
not readily dissolve in water
 Cholesterol is a sterol
Functions of Cholesterol
 Essential
component of cell membrane
 Produced by the liver
 Found only in animal products
 Forms important hormones
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Estrogen, testosterone, vitamin D
 Precursor
to bile acids
Lipids in Foods
Hidden Fat
Look on the Nutrition Facts
 Look on the lists of ingredients
 Control portion size
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Reduce-Fat Foods
Total energy is about the same
 Sugar is commonly added in place of fat
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Fat Substitutes
Water (diet margarine)
 Z-trim (starch derivative that binds with water)
 Fiber cellulose (Maltrin, Stellar, Oatrim)
 Dairy-Lo (protein globules)
 Olestra (links fatty acid to sucrose)
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not digested
fat-soluble vitamins issue
Digestion of Fat in the Stomach
Gastric lipase works only in an acidic environment
 Gastric lipase acts on triglycerides containing short & medium
chain fatty acid
 Longer fatty acid chain is not affected by the stomach
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Digestion of Fat in the Small Intestine
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Primary site of fat digestion
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CCK stimulates pancreas to release pancreatic lipase
Pancreas release lipase
Bile acid emulsifies digested fat
Fat is broken down to monoglycerides and fatty acids
Absorption of Fat
Diffuse into the absorptive cells
 Short and medium chain (<12 C) fatty acids are water soluble
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Enters the portal system
Long chain fatty acids reforms into TG
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Enters the lymphatic system
Carrying Fat in the Bloodstream
Water (blood) and oil (fat) are incompatible
 Unique system of fat transportation is needed
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Transportation of Digested Fat
Re-formed into triglycerides
 Packaged into chylomicrons
 Lipoprotein lipase breaks down triglycerides in the chylomicrons
 Fatty acids are absorbed by cells
 Takes 2-10 hours to clear chylomicron
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Lipoproteins
Transportation of Synthesized Fat
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Fat and cholesterol made primarily by the liver
Very Low Density Lipoprotein (VLDL)
Low Density Lipoprotein (LDL)
Receptor pathway for cholesterol uptake
Scavenger pathway for cholesterol uptake
Scavenger Pathway
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Scavenger WBC removes (oxidized) LDL from circulation
Prevents oxidized LDL from returning to circulation
Build-up of plaque on walls of the blood vessels
Leads to plaque and atherosclerosis
Causes: smoking, diabetes, HTN, homocysteine, LDL
Antioxidant
 Reduces
oxidation
 Slows
LDL uptake into scavenger cells
 Need for supplements of antioxidants?
High Density Lipoprotein (HDL)
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Synthesized by liver and intestine
High proportion of protein
Picks up cholesterol from dying cells and other sources
Transfers cholesterol to other lipoprotein for transport to the liver for
excretion
HDL can also transfer directly back to the liver
Benefits of (a high) HDL (level)
Remove cholesterol from the blood stream
 HDL may block oxidation of LDL
 Reduce risk of heart disease
 Pre-menopausal women have higher HDL
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Functions of Lipids
Provide energy
 Efficient storage of energy
 Insulation
 Protection
 Transport fat-soluble vitamins
 Satiety
 Flavor and mouth feel
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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)
Cis and Trans Fatty Acid
Health Dangers of Excessive Trans Fatty Acid
 Raises
LDL
 Lowers HDL
 Increases
risk for heart disease
 Current intake is~3% of total kcals
 Soon to be on food labels
Minimize Intake of Trans Fatty Acid
 Limit
use of hydrogenated fats
 Limit deep-fried foods
 Limit high fat baked goods
 Limit use of non-dairy creamers
Rancidity
 Decomposed
oils
 Breakdown of the C=C double bonds by ultraviolet rays,
&/or O2
 Yields unpleasant odor and flavor
 PUFA more susceptible
 Limits shelf life
Prevention of Rancidity
 Hydrogenation
 Addition
of vitamin E
 Addition of Butylated hydroxyanisol (BHA) and
Butylated hydroxytolune (BHT)
Recommendation
No RDA
 4% of total kcal should come from essential fatty acids
 No more than 15% from PUFA
 Current diet supplies ~33% of total kcal from fat
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much from animal, whole milk, pastries, cheese, margarine, and mayo
The American Heart Association
For high risk individuals
 <20-30% of total kcal from fat/day
 <7-10% from saturated fat (includes trans fatty acid)
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<200-300 mg cholesterol a day
The National Cholesterol Education Program
 Reduce
saturated fat intake to 7% of total energy
 Reduce cholesterol to 200 mg/day
Other Recommendations
Fat intake can be higher as long as saturated and trans fatty acid
are minimal
 Eat diet with plenty of fruits and vegetables
 Cut down on red meats
 Cut down on simple sugars and refined CHO
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Signs of a Heart Attack
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Intense, prolong chest pain
Shortness of breath
Sweating
Nausea and vomiting
Dizziness
Weakness
Jaw, neck, shoulder pain
Irregular heartbeat
Cardiovascular Disease
Symptoms take years to develop
 Plaque build-up can begin in childhood
 Myocardial infarction (heart attack)
 Cerebrovascular accident (stroke)
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The Road to a Heart Attack
Risk Factors for Heart Disease
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Family history
Smoking (even second hand)
High blood pressure
High blood cholesterol (hyperlipidemia)
 >200 mg/dl of total cholesterol
 HDL < 40 mg/dl
Diabetes
Lack of regular exercise and obesity
Reducing Your Risks--Primary Prevention
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Reduce dietary saturated fat and cholesterol
Increase MUFA and PUFA to recommended amounts
Increase dietary fiber
Increase activity; develop a exercise routine
Adequate caloric intake to maintain healthy weight
Secondary Prevention (After a Heart Attack)
 Primary
prevent techniques
 Medication
 Hormone therapy
 Megadoses of vitamin E (400-800 IU/day)
Lowering LDLs
See your doctor to assess for other conditions
 Reduce dietary saturated fat and cholesterol
 Increase MUFA and PUFA
 Increase dietary fiber (soluble)
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Lowering Blood TG
Is the most diet-responsive blood lipid
 Overeating
 Limit alcohol
 Limit simple sugars
 Small frequent meals
 Include fish in the diet
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Raise the HDL
Physical activity
 At least 45 min./day, 4 days a week
 Avoid smoking
 Eat regularly
 Eat less total fat
 Moderate intake of alcohol increases HDL
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Other Possible Methods
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Cholestin (from Chinese red yeast) reduces cholesterol
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Benecol and Take Control margarine
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Plant stanol/sterol esters
Cholesterol-lowering effects
Decrease absorption of cholesterol and lowers amount returning via enterohepatic
circulation.
Liver takes up more cholesterol from the blood
Strategies for Reducing the Risk
Eat less saturated fat & trans fatty acids
 Replace with MUFA and essential fatty acids
 Eat fish 2x a week
 Eat plenty of fruits and vegetables
 Eat more whole grains and less refined CHO
 Eat at least 3 meals regularly
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Strategies
Consume moderate alcohol
 Moderation in coffee, replace with tea
 Moderation in salt
 Meet calcium needs
 Avoid excess iron intake
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