Triglycerides
= 3 fatty acids bound to 1
glycerol
Most common form of fat in food
Major form of energy storage in
humans
Triglyceride
Fatty Acids
= carboxylic acids with long
chain hydrocarbon side groups
Rarely free in nature, usually
occur in an esterified form
Fatty acid composition of a lipid
will determine its characteristics
Saturated v. unsaturated double bond
Double Bonds
Unsaturated fatty acids contain
double bonds
A fatty acid with one double bond
is called mono unsaturated
A fatty acid with two or more is
called polyunsaturated (PUFA)
Fat Comparisons
Unsaturated Fatty Acids
2 double bond configurations
Cis - naturally occurring
Trans - most produced during processing
 |
 |
|
| Saturated Fatty Acid |
Unsaturated Fatty Acid
|
Unsaturated fatty acids can exist in two forms, cis and
trans depending upon the arrangement of the portions of the fatty acid
molecules around the double bonds. The Food and Drug Administration has
proposed labeling of trans fatty acids in foods. Naturally occurring fatty
acids are in the cis conformation.
The double bonds in lipid molecules are very reactive
towards oxygen. The products of lipid oxidation have undesirable flavors and
lipid oxidation leads to what is termed rancidity.
Hydrogenation
H
H H H
-C-C=C-C- Unsaturated
H
H
E
×
+2H
H
H H H
-C-C-C-C- Saturated
H
H H H
Common Food Antioxidants
= Molecules that prevent oxidation
Butylated hydroxytoluene (BHT)
Butylated hydroxyanisole (BHA)
Propyl gallate (PG)
Vitamin C
Vitamin E
Effect of Hydrogenation
= Reduces # of double bonds
More solid at room temperature
More stable toward oxidation
More trans fatty acids
Essential Fatty Acids
Humans can produce most fatty acids
it needs but not some that contain double bonds
Provided linoleic acid, humans can
synthesize all the fatty acids it needs
Linoleic Acid Requirements
Not well-established
Most adults have large amounts
stored in adipose tissue
Estimates for calories from
linoleic acid
Adults should consume ~ 1%
Infants 2%
Phospholipids
Any lipid containing a phosphorus
Major lipid components of
biological membranes
Example: Lecithin (phosphatidyl choline)
Plasma Triglyceride Levels
|
Normal Triglycerides |
Less than 200 mg/dl |
|
Borderline High |
200 to 400 mg/dl |
|
High Triglycerides |
400 to 1000 mg/dl |
|
Very High |
Greater than 1000mg/dl |
Cholesterol
Cholesterol is utilized by the body for:
Bile salts
Membrane structure
Myelin synthesis
Vitamin D synthesis
Steroid hormone synthesis.
Lipoproteins
clusters of lipids associated with
protein
transport vehicle for proteins in
blood and lymph
HDL - high density
lipoprotein
- return cholesterol to liver
- contain lots of protein
LDL - low density
lipoprotein
- transport cholesterol from liver
- contain lots of cholesterol
Factors often listed as risk factors Risk Factors for
Coronary Heart Disease
Serum cholesterol > 200 mg per
100 ml serum
Personality - drive, ambition,
worry
Hypertensive
Parents (genetic influence)
Smoking
Weight
Physical activity
Cholesterol intake
Average person consumes
from 400 to 800 mg/day
Synthesis by the body is
between 1,000 and 2,000 mg/day
As intake increases, synthesis
decreases and vice versa
