Lecture 6- Lipids(fats) Flashcards
0
Q
Functions of lipids
A
- provide energy: at rest, fasting and during moderate intensity excercise, prolonged excercise
- energy storage
- padding (protection) and insulation
- component of the cell membrane
- synthesizes compounds
- absorption and transport fat-soluble vitamins
- satiety
- flavor and mouthfeel (the texturethat the food has in your mouth
1
Q
Lipid molecule
A
- structure C, H, O
- does not dissolve in water
- 3 type of lipids in food:
• triglycerides (TG)
• phospholipids
• sterols
2
Q
Triglycerides
A
- three fatty acid molecules • carboxylic acid, COOH, alpha end • methyl, CH3, omega end - one glycerol molecule • glycerol is an alcohol (COH)
3
Q
Fatty acids facts
A
- fatty acids vary by: • chain length • degree of saturation • structure of carbon bonding • variation impact fatty acid properties - TG (and foods) are comprised of a mixture of fatty acids - some fatty acids are essential - some are better or us than others
4
Q
Fatty acids: Chain length
A
- short chain FA: fewer than 6 carbons
- medium chain FA: 6-12 carbons
- long chain FA: 14 or more
- shirt and medium FA chains get directly absorbed into circulation, liquid at room temperature
5
Q
Fatty acids: degree of saturation
A
- saturated: no double bond
- monounsaturated: one double bind
- polyunsaturated: 2 or more double bond
- mono an poly= UFA (unsaturated fatty acids)
6
Q
Fatty acids: structure of C bonding
A
Double vond can be found in:
- cis: kink
• H on same side
- trans: linear
• H on opposite side
- impacts shape and fluidity
7
Q
Partially hydrogenated fatty acids (trans fat)
A
What:
- H added under pressure= H opposite side C chain
Why:
- pack= more solid - less prone to become oxidized (rancid)
8
Q
Essential fatty acids
A
- 18 C long omega 3&6 are essential
- linoleic acid: omega 6
• most vegetables oils, nut oils - alpha linolenic acid: omega 3
• canola and soybean oil, flaxseed oil, walnuts
• cold water fish oils are a source of EPA and DHA
• omega 3 associated with reduced heart disease
9
Q
Essential fatty acids metabolize to….
A
- metabolize to longer FA
- precursors of Eicosanoids
• hormone like properties that regulate cellular functioning (prostaglandins, thromboxanes, leukotrienes)
• “local hormones”
• eisanoids from omega 3s reduce inflammation, blood clotting and acts as vasodialators (favorable, heart healthy) - blood clotting, vasoconstriction/ dilation, inflammation, immune function, and other body process
10
Q
Saturated fats
A
- bad
- raises LDL cholesterol and HDL cholestetol
(LDL is really bad, risk factor for a lot of heart disease; HDL is a good thing) - coconut, palm, palm kernel oil, butter, cream, cheese, beef fat, whole milk
11
Q
Trans fatty acids
A
- extremely bad
- raise LDL cholesterol, and lowers the the HDL cholesterol
- margarine, crackers, cookies, fried-foods
12
Q
Monounsaturated
A
- good
- reduces LDL cholesterol, and POSSIBLELY raises HDL cholesterol
- olive oil, canola oil, peanut oil, cashew nuts
13
Q
Polyunsaturated
A
- good (some better than others)
- vegetable oils, fish oils, canola, cottonseed
14
Q
Saturated Fat Needs
A
- AMDR: 20-35% Kcals
- general recommendations:
• saturate fat:
~ dietary guidelines: <7%
~ 20 g saturated fat (AHA: 15g)
15
Q
Trans fat needs
A
- as low as possible, <2g on a 2000 kcal diet)
• current intake ~ 3% kcals
16
Q
Adequate intake for EFA
A
- linoleic: most meet with no problem
- alpha-linolenic acid: less often met
• men (19-50yrs): 1.6g/d
• women (19-50yrs): 1.1g/d
17
Q
Phospholipids structure
A
- glycerol
- 2 fatty acids
- phosphate containing molecule
18
Q
Phospholipids
A
- properties: hydrophobic and hydrophilic ends
- liver makes phospholipids (not essential)
- foods: animal cell membranes, egg yolks, soybeans
19
Q
Function of phospholipids
A
- emulsifier
- part of the cell membrane (phospholipid bilayer)
- helps with fat digestion/ absorption forming micelles (lecithin+ bile salts+ electrolytes= bile)
- helps transport dietary fats in circulation (phospholipid shell)
- in food: emulsifier (mayonnaise, salad dressing)
20
Q
Lipids digestion, absorption, and transport
A
- TG are large: hard for lipase to reach
- bile: emulsifies fat, making smaller droplets called micelles
- micelles: water soluble and stay suspended in water based intestinal content
- lipase
- monoglycerides and FFA are absorbed
21
Q
Phospholipids shell of lipoproteins
A
- transports lipids and chilesterol in the blood
- phospholipids shell
- protein
- TG and chol rich interior
22
Q
Sterols
A
- rings of carbon
- found in food and made in body
- cholesterol is most common dietary sterol
• synthesized by animals amd humans, not plants - plants make differeny sterols: actually healthy and may reduce cholesterol
23
Q
Cholesterol functions
A
- base structure of
• bile salt precursor; bile salts make bile
• vitamin D
• hormones: testosterone, estrogen
- cell membrane structure
24
Q
Cholesterol (a sterol)
A
- sources: produced by animals= animal product
- non essential: liver makes cholesterol
- health: raises LDL cholesterol
- dietary guidelines:
• <300 mg/d
3oz meat= 100mg
