BPK 110 Lecture 5: Fat, Phospholipids, and Sterols

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LECTURE FIVE FAT, PHOPHOLIPIDS, AND STEROLS
Triglycerides
- Main dietary lipid
- Hydrophobic (water-fearing) molecules
- Made of glycerol backbone and three fatty acids
o Fatty acids differ in length, degree of saturation (# of hydrogen atoms attached
to FA), and geometric organization
Saturated FA (Fatty Acids)
- No double bond = most saturated w/ hydrogens = saturated fatty acids (SFA)
- Longer chain SFA
o Most common in animal products
o High consumption = increased risk of cardiovascular disease
o Absorbed thru portal vein > lymphatic system (less likely stored)
- Medium chain SFA
o 6-12 carbons
o Found in tropical oils
o May be associated w/ improved body composition
- Short chain SFA
o <6 carbons
o Produced when dietary fibre is fermented in colon
o May promote colonic health, reduce CVD risk
- Med. and short chain absorbed thru portal vein only
Unsaturated Fatty Acids
- One (mono) or more (poly) double bonds
- Liquid @ room temp; most common in plants, fish
- Monounsaturated FAs
o One double bond
o + effect on LDL cholesterol
- Polyunsaturated FAs
o 2+ double bonds
o Essential FA: first double bond before position 9 (ex. omega-3 or -6)
Essential Fatty Acids
- Huas a’t proess PUFAs / doule ods i oega-6/-3; needed from diet
o Omega-6
Lineoleic acid found in corn, safflower oils
Archidonic acid only essential when lack lineoleic in diet for body to
process
o Omega-3
Alpha-linolenic acid
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These are processed from a-linolenic acid: Eicosapentaenoic acid
(EPA) and Docosahexaenoic acid (DHA)
Found in fatty fish, fortified foods
Essential Fatty Acid Funcitons
- Formation of phospholipid bilayer of cell membrane
o Growth, skin integrity, fertility, red blood cell structure, etc.
- Arachidonic acid and docosahexaenoic acid (DHA)
o Brain development in infants/children
- Long chain omega-6/-3 help form eicosanoids
Eicosanoids
- Hormone-like molecules
- Effects depends on essential fatty acid derived from
- Derived from omega-3 fatty acid:
o Vasodilation
o Inhibition of blood clotting
o Reduce inflammation
o Lower blood cholesterol
- Derived from omega-6 fatty acid:
o Vasoconstriction
o Promote blood clotting
o Promote inflammation
Symptoms of Essential Fatty Acid Deficiency
- Dry, scaly skin
- Liver abnormalities
- Poor healing
- Impaired vision
- Growth failure (infants)
Cis vs. Trans Fatty Acids
- Unsaturated fatty acids, 2 hydrogen atoms surrounding double bond arranged two ways
o Cis FA: hydrogens on same side of double bond, kinking chain (curved, circular
bond)
o Trans FA: hydrogens on opposite side of double bond (straight, long bond)
Trans Fat
- Rare in nature
- Can be made thru hydrogenation
o Improves shelf life
- Increase heart disease risk
o Higher LDL (bad cholesterol) and HDL (good cholesterol)
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