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HES 200: Introduction to Nutrition > Lipids > Flashcards

Lipids Flashcards

1
Q

What are the seven functions of lipids?

A
  1. Energy! 9kcal/g; takes less energy to store and holds less water than carbohydrates
  2. Protection
  3. insulation for body and axons (myelin sheath)
  4. carries and stores fat soluble vitamins (ADEK) and essential fatty acids
  5. conversion to other molecules needed by the body such as amino acids, phospholipids, lipoproteins, hormones
    etc
  6. makes up the lipid bilayer in the cell
  7. adds taste, texture and smell to food and aids in satiety (in mouth and stomach) and slows gastric emptying due to release of CCK
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2
Q

What are the basic building blocks of a lipid?

A

fatty acid; omega end and acid end with carbon chain in
between; can be short, medium, long chain or very long >22

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3
Q

What are lipids made of?

A

made of carbon, oxygen and hydrogen but less oxygen than carbohydrates

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4
Q

What is the structure of fatty acids?

A

chains of carbon molecules; every C always has 4 bonds either to C, H, O, or OH

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5
Q

What does it mean when a C chain is saturated?

A

A C chain is “saturated” eg. when all 4 bonds linked
with all possible hydrogens

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6
Q

When does a C chain become unsaturated

A

Remove 1 or more H, then a double bond is made (to
keep the 4 bonds) so now it is an unsaturated FA –
(can be mono or poly unsaturated, depending on # of
double bonds)

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7
Q

What is considered a short chain fatty acid?

A

< 6 C

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8
Q

What is considered a medium chain fatty acid?

A

6-12 C

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9
Q

What is important to know about medium fatty acids?

A

not naturally occuring in foods except coconut; can be made synthetically; helpful for lipid malabsorption

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10
Q

What is considered a long fatty acid?

A

> 12 C

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11
Q

What is considered a very long fatty acid chain?

A

> 22 C

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12
Q

What are some things to know about saturated fatty acids?

A
  • solid at room temperature (can stick to artery walls)
  • found mostly in animal products
  • generally less healthy
  • can use in frying etc.
  • food don’t spoil as easily; more stable
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13
Q

What are some things to know about unsaturated fatty acids?

A
  • liquid at room temperature less tendency to oxidize on artery walls
  • found mostly in plant foods
  • generally more healthy
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14
Q

What is an example of naming of a fatty acid?

A

C18 omega 3 polyunsaturated fatty acid

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15
Q

Which fatty acids are essential in a diet? why?

A
  • omega 3 and 6 FA
  • body can’t make the double bonds at the 3 and 6
    carbon
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16
Q

How are trans fatty acids made?

A

made by the process of hydrogenation

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17
Q

What does hydrogenation do?

A

Hydrogenation makes a liquid oil into a semi
solid (spreadable fat) by breaking bonds and adding H in a trans formation

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18
Q

What does hydrogenation do to food?

A

Increases shelf life and improves consistency of foods but increases health risks

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19
Q

What are some pros of Butter compared to margarine?

A
  • All natural, right from the cow, maybe salt added
  • Tastes great!
  • CLAs (conjugated linoleic acid; naturally occurring trans fats found in dairy products and help prevent
    cancer)
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20
Q

What are some cons of Butter compared to margarine?

A

Animal fat; saturated

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21
Q

What are some pros of margarine compared to butter?

A
  • Non-hydrogenated
  • mostly veg. oil with a bit of saturated fat added; beta
    carotene added for colour
  • Plant fat; unsaturated
  • Choose ones made with plant oils with more omega 3
    fats and less omega 6 eg. canola
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22
Q

What are some cons of margarine compared to butter?

A

Hydrogenated; trans fats! (don’t buy these ones!)

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23
Q

Which fatty acids should you have more often?

A
  • all plant food sources such as oils, nuts, seeds, avocados, except tropical oils as more saturated
  • choose lean meats, poultry, eggs, fish, cheese, dairy
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24
Q

Which fatty acids should you have less often?

A

processed meats such as bacon, salami, hot
dogs and sausages, high fat cheeses, any foods with
hydrogenated oils and tropical oils

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25
Q

Why is omega 3 fatty acid essential for our body?

A
  • makes hormones involved in heart and immune system functioning
  • parts of cells of cerebral cortex and retina
26
Q

Where is omega 3 found?

A

found in canola, soybean, flax and walnut oils, human milk, cold water fatty fish and fortified foods

27
Q

Why is omega 6 fatty acid essential for our body?

A
  • play a role in cell membrane formation
28
Q

In what foods can omega 6 fatty acids be found?

A

-found in nuts, seeds, whole grains, leafy greens, vegetable oils eg. sunflower, safflower, corn oils
- in processed foods

29
Q

What happens if you have too much omega 6 fatty acids

A

too much fosters systemic inflammation and
increased health risk

30
Q

What does it mean that Omega 3s are more unstable?

A

can’t heat as high eg. canola but high omega 3 oils like flax need to be kept in dark and cold

31
Q

Concerns re fish oil supplements?

A

Possible contaminants, unbalanced, “food first
approach”

32
Q

What is the best source of Omega 3?

A

FISH

33
Q

What are the best oils for omega 3?

A
  • flax
  • canola
  • walnut
  • grapeseed
34
Q

Cis vs trans fatty acids formation?

A

Cis fatty acid has both hydrogen atoms located on the same side. On the contrary, trans fatty acid has the two hydrogen atoms on opposite sides. Fatty acids with cis configuration are typical in natural foods. Most of the trans fatty acids are formed during the process of hydrogenation of vegetable oils.

35
Q

Omega 3 fortified foods?

A

margarine, yogurts, eggs, soy milks,
granola bars, breads, juices etc.

36
Q

What are the “family” of omega 3 fatty acids that foods can be fortified with?

A

ALA, DHA, and EPA

37
Q

What is there to know about ALA, DHA, and EPA?

A
  • ALA easier to get in diet but it must be converted in body
  • DHA and EPA harder to get in diet but are the best kind as they are readily usable by the body
38
Q

What do ALA, DHA, and EPA stand for?

A
  • Alphalinolenic acid
  • Docosahexaenoic acid
  • Eicosapentaenoic acid
39
Q

What is a weekly recommendation to get enough omega 3 in the diet?

A

2 servings of cold water fatty fish recommended per week

40
Q

Lables with how much trans fat are allowed to say they are trans fat free? What is the issue with this?

A

< .2
- people who eat a lot of pkg food then could still consume quite a bit during a day

41
Q

What are triglycerides? How are they made and stored? Are high tri levels bad?

A
  • most common type of fat in food and stored in the body
  • 3 fatty acids + 1 glycerol
  • made from excess carbohydrates, fats, and/or protein
  • stored in fat tissue
  • high triglyceride levels in blood are a health risk
42
Q

What are eicosanoids? What do they do for the body?

A
  • made from essential fatty acids derived from C20 unsaturated FA
  • act like hormones
  • make prostaglandins and leukotrines for immune function
  • play a role in cell membrane
  • increase vascular permeability
43
Q

What are sterols? Where are they found?

A
  • sterol molecule of C rings with side chains of C, H, O
  • part of every cell membrane (cholseterol)
  • component of myelin sheath
  • precursor to Vit. D (calcitrol), sex hormones (eg. estrogen etc.), cortisol (eg. stress response)
  • component of bile
  • found ONLY in animal products shellfish, eggs, liver, meats, dairy
44
Q

Are eggs ok for people with high cholesterol?

A
  • an egg a day is still fine or those with high cholesterol
  • nutrients mostly in the yolk, protein in the white
45
Q

How much of the cholesterol we eat do we absorb? How much does it contribute to the body’s total cholesterol?

A

about 50%
- contributes to 40% or less of body’s cholesterol

46
Q

Do we make cholesterol?

A
  • yes
  • endogenous cholesterol in liver
  • accounts to 60% or more of total body cholesterol
47
Q

Why can too much cholesterol be bad?

A
  • part of arterial plaques, leading to CVD and high BP
48
Q

What are phospholipids?

A
  • fatty acid plus a phosphate group
  • lipid bilayer in cell membrane
49
Q

What are lipoproteins? Why are they important?

A
  • lipid molecules containing proteins
  • important as a transport molecule in blood
50
Q

Which fatty acid chains can be directly absorbed into the blood stream?

A

short and medium chain FA

51
Q

What happens to fats when we eat them?

A
  • they are broken down into FA by enzymes and bile (bile acts as an emulsifier to mix fat and watery liquids eg. digestive enzymes)
52
Q

In short what are lipids used for?

A
  • used for energy, made into other molecules and excess fats are formed into triglycerides and stored in adipose
53
Q

Why can long chain fatty acids not be absorbed into blood? What happens instead?

A
  • molecules are too big to be absorbed directly
  • put into a lipoprotein (chylomicron specifically) in the GI epithelium, to be carried in the lymph and then into the bloodstream, then delivered to body cells
54
Q

What goes into the lipoprotein?

A
  • cholesterol, triglyceride, protein and phospholipid
55
Q

What happens to a chylomicron? How does it get into the bloodstream?

A
  • absorbed into lymph through lacteal
  • enters blood stream at left subclavian vein
56
Q

What happens to a chylomicron once it is in the bloodstream?

A
  • travels to fat or muscle cells
57
Q

What happens to the chylomicron once it is at a fat or muscle cell?

A
  • enzymes break the chylomicron down into all its parts; glycerol and fatty acids are absorbed into the cell
  • reformed into a triglyceride and stored in adipose tissue
58
Q

What happens to the remnants of the chylomicron after the cell breaks it down?

A
  • go to the liver
59
Q

At the liver, what happens to the remnants of chylomicron

A
  • the remnants are formed into new lipoproteins, VLDLs (very low density lipoproteins)
  • they are released into blood; some triglyceride is dropped off at fat cells;
  • the lipoprotein is now a LDL (low density
    lipoprotein) (“bad” cholesterol)
60
Q

What happens to LDLs?

A
  • some LDLs are taken up by apolipoprotein B on the cells and metabolized; but there are limited receptors for this
  • some LDLs are metabolized by HDLs (high density lipoprotein (“good” cholesterol); but these are limited
  • if there are still LDLs in the blood then they oxidize on artery walls contributing to atherosclerosis, CVD, high BP etc.
61
Q

HDLs are limited; the best/main thing that increases HDLs is ……

A

exercise and healthy eating practices (reverse cholesterol transport)

62
Q
  • Receptors and HDLs are limited so the more long chain fatty acids (animal, saturated
    fats) that people eat then…….
A

the more chylomicrons made and go through the whole
process, with remnants going back to liver and making more cholesterol and VLDLs. . . . . a continuous process which would lead to more build up on artery walls
thus . . .. . atherosclerosis etc

HES 200: Introduction to Nutrition (3 decks)

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