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Nutrition 1 (Semester II) > 14a. Lipids & Essential Fatty Acids > Flashcards

14a. Lipids & Essential Fatty Acids Flashcards

1
Q

What has been the traditional thinking on saturated fat?

A

Diet high in saturated fat can increase serum cholesterol
Leading to heart disease
(Ancel Keys, 1950s)

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2
Q

What has traditionally been the dietary recommendations around saturated fat?

A

Low fat diet
High carbs
Swap animal fats for seed oils

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3
Q

What are the functions of white adipose tissue (WAT)?

A 
Protect organs
Insulation
Energy storage
Hormone secretion
Enzymes and cytokines
Growth factors
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4
Q

Examples of different types of lipids

A 
Individual fatty acids
Triglycerides
Phospholipids
Cholesterol
Fat soluble vitamins
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5
Q

Where are phospholipids found?

A

In every cell membrane

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6
Q

Where are sphingolipids found?

A

In nerve cell membranes

e.g. myelin

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7
Q

What is the role of glycolipids?

A

Cell identity

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8
Q

What are cerebrosides?

A

Glycosphingolipids found in the brain

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9
Q

Examples of functions of lipids

A 
Insulation
Energy production
Energy storage
Cell membrane structure
Steroid hormones
Absorption of fat soluble vitamins
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10
Q

How do lipids support energy production?

A

1g of fat = 9kcals

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11
Q

How do lipids support energy storage?

A

More efficient form of energy storage

so body stores any excess energy as fat

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12
Q

How do lipids support cell membrane structure?

A

Phospholipids and cholesterol stabilise cell membranes

Allows for fluidity - crucial

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13
Q

How do lipids support insulation?

A

Layer of insulation in subcutaneous tissue

Protection around organs

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14
Q

How do lipids support steroid hormones?

A

Progestogens, androgens, oestrogens, glucocorticoids, mineralocorticoids are derived from cholesterol

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15
Q

How do lipids support growth and development?

A

Brain is rich in arachidonic acid and DHA

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16
Q

How are fatty acids chemically structured?

A

Hydrocarbon chains with an acid (carboxylic) group at one end and a methyl group (omega) group at the other

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17
Q

How many carbons do short chain fatty acids have?

A

Up to 5

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18
Q

How many carbons do medium chain fatty acids have?

A

6-12

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19
Q

How many carbons do long chain fatty acids have?

A

14-22

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20
Q

How many carbons do very long chain fatty acids have?

A

22+

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21
Q

Where do SCFA and MCFA travel to?

A

Directly to the liver

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22
Q

What can SCFAs and MCFAs be used for?

A

Energy

Ketones

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23
Q

Which fatty acid chain can be used as a source of energy before exercise?

A

MCFA

as MCTs

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24
Q

What can LCFAs and VLCFAs be used for?

A

Build cell membranes

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25
Q

When are SCFAs produced?

A

When dietary fibre is fermented in the colon

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26
Q

Examples of common SCFAs

A

Acetate
Butyrate
Propionate

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27
Q

What is butyrate important for?

A

Colon health - primary energy source for colonocytes
Supports intestinal tight junctions
Anti-inflammatory properties

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28
Q

What is the naming structure of fatty acids?

A

Number of carbon atoms
Number of double bonds
Number of carbons from the omega end to first carbon at a double bond

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29
Q

How do unsaturated fats become saturated?

A

By the addition of a hydrogen

as in hydrogenation when oils are made into solid spreads

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30
Q

What does hydrogenation do?

A

Turns a natural fatty acid into an unnatural form

damaging to health

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31
Q

What are saturated fatty acids?

A

Contain no carbon double bonds
All the carbons are completely saturated with hydrogen bonds
Solid at room temperature

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32
Q

What are unsaturated fatty acids?

A

Contain one or more double bonds between carbons

Liquid at room temperature

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33
Q

What are monounsaturated fatty acids?

A

Have one double bond in the chain

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34
Q

What are polyunsaturated fatty acids?

A

Have several double bonds in the chain

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35
Q

What impact does the number of double bonds have on the fatty acid?

A

The more double bonds there are, the less stable it is

Increases susceptibility to oxidation

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36
Q

How are trans fats produced?

A

High temperatures

Hydrogenation

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37
Q

What products are trans fats found in?

A

Margarine
Processed foods
Refined veg oils

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38
Q

Why are trans fats bad for cell membranes?

A

Stiffens them
Makes them prone to oxidation
Alters their protective action/permeability

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39
Q

What diseases are trans fats linked to?

A

CV disease
Insulin resistance
Cancer

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40
Q

Are the majority of natural fats cis or trans?

A

Cis

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41
Q

What is conjugated linoleic acid (CLA)?

A

A natural trans fat found in grass-fed meat and dairy products

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42
Q

What are the benefits of CLA?

A

Helps increase lean muscle mass

Helps decrease body fat

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43
Q

Why are trans fats unsaturated but behave like saturated fats?

A

Because they don’t kink

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44
Q

What type of fat is the major form of dietary fat?

A

Triglycerides

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45
Q

Which type of fat is the fat that is stored in the body and circulated in the blood when released for energy?

A

Triglycerides

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46
Q

How are triglycerides chemically constructed?

A

Lipid molecules

1 unit of glycerol and 3 x fatty acids

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47
Q

How can the three fatty acids differ?

A 
In length (number of carbon atoms)
Degree of saturation (number of hydrogen molecules attached)
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48
Q

Which pathology has high levels of triglycerides in the blood been linked to?

A

Atherosclerosis

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49
Q

When does the body synthesise triglycerides?

A

Whenever calorific intake exceeds energy requirements

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50
Q

What process is utilised to convert excess dietary energy to triglycerides?

A

Lipogenesis

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51
Q

Where is excess digested fat deposited?

A

Adipose tissue

52
Q

Where does lipogenesis take place?

A

Adipose tissue

Liver

53
Q

How do adipocytes acquire triglycerides?

A

From circulating lipoproteins, chylomicrons, VLDL

via blood vessels

54
Q

What happens during lipogenesis?

A

Acetyl-CoA is converted to triglycerides for storage in fat

55
Q

When are fatty acids synthesised?

A

When there is an excess of carbohydrates

56
Q

How is acetyl-CoA built up?

A

With 2 carbon units to produce palmitic acid

57
Q

Where does fatty acid synthesis take place?

A

Liver
Adipocytes
Kidneys
Lactating mammary glands

58
Q

What is lipolysis?

A

The breakdown of triglycerides for energy

59
Q

What happens during lipolysis?

A

The fatty acids from triglycerides hydrolysed by lipase and released from adipocytes into circulation

60
Q

What is lipolysis stimulated by?

A

Adrenaline/noradrenaline (when stressed)
Adrenocorticotropic hormone (ACTH)
Glucagon and growth hormone
Thyroid stimulating hormone/thyroxine

61
Q

What affect does insulin have on the hormones that stimulate lipolysis?

A

It has an antagonistic effect

so insulin resistance = lipogenesis = central adiposity

62
Q

What happens when fatty acids are broken down to create energy?

A

Fatty acids cross the cell membrane, traverse the cytosol and enter the mitochondria (with help of carnitine)

The fatty acids undergo beta-oxidation where they are broken down in 2-carbon blocks as acetyl-CoA which is oxidised via Krebs cycle

63
Q

Which amino acid facilitates the transport of fatty acids across the mitochondrial membrane?

A

Carnitine

64
Q

When does fat become the primary fuel for energy?

A

When carb levels are low

65
Q

What are produced for energy when glucose is in short supply?

A

Ketones

66
Q

When are ketones usually produced?

A

Overnight
During dieting
During fasting

67
Q

What is ketogenesis?

A

The process of making ketones

68
Q

What happens during ketogenesis?

A

Acetyl-CoA is converted to ketones

69
Q

Which ketones are produced during ketogenesis?

A

Acetoacetate

Beta-hydroxybutyrate

70
Q

Which ketone can acetoacetate produce?

A

Acetone

71
Q

How does acetoacetate convert to acetone?

A

Via decarboxylation

removal of a carboxyl group

72
Q

What characteristic does acetone have?

A

Pear drop smell to breath

73
Q

How many grams of carbs a day is needed to reach ketosis?

A

No more than 40g

74
Q

Which pathologies have seen benefits via a low carb diet?

A

Weight loss
Epilepsy
Parkinson’s
AZD

75
Q

What is the build up of acetone in the body called?

A

Ketoacidosis

76
Q

What is ketoacidosis?

A

Dangerous condition that occurs when there is insufficient pancreatic insulin to regulate serum beta-hydroxybutyrate

77
Q

Which enzymes, and where, aid the digestion of triglycerides?

A

Gastric lipase - stomach

Pancreatic lipase - duodenum

78
Q

Which substance, along with lipases, facilitates the breakdown of lipids?

A

Bile

79
Q

What happens to triglycerides in the body once they are broken down?

A

The fatty acids and monoglyceride are transported into enterocytes
Rebuilt in the cell
Packaged into chylomicrons
Transported into bloodstream via lymphatic system
Used or stored in adipose tissue

80
Q

How to optimise lipid digestion

A

Chew adequately
Avoid drinking with meals
Increase glycine and taurine - components of bile
Increase bile production - bitters, B6/zinc rich foods, choleretics, stress management
Support bile flow - good hydration, cholagogues
Stimulate bile secretion

81
Q

How can bile production be increased?

A

Bitters
B6/zinc rich foods
Choleretics - dandelion, artichoke, turmeric
Stress management

82
Q

How can bile flow be supported?

A

Good hydration

Cholagogues - dandelion, artichoke, turmeric

83
Q

How can bile secretion be stimulated?

A

Olive oil

84
Q

How many grams of total, saturated, polyunsaturated and O3 fats are recommended for a female consuming 2000kcals per day?

A

Total: 44-78g
Saturated: 22g (10% of energy)
Polyunsaturated: 13-24g
O3: 1.1-4.4g

85
Q

What does the Eatwell Guide recommend in terms of fat consumption?

A

Choose low fat dairy

Unsaturated oils/spreads (eaten in small amounts)

86
Q

Why are the Eatwell Guide recommendations flawed?

A

No emphasis on oily fish, avocado, nuts, seeds, EVOO, egg yolk, grass-fed meat
Low fat dairy options often contain high amounts of sugar
Unsaturated oils may be refined/contain trans fats

87
Q

What did the PURE study of 2017 found regarding high carb/high fat diets?

A

High carb diets lead to highest mortality rates

People consuming more fat (35% of total energy) were less likely to die than those consuming 10% daily energy

88
Q

Which fats should we have in the diet?

A

Natural, unrefined
Saturated
Monounsaturated
Polyunsaturated

89
Q

Which vitamin is important to consume when including fats in the diet?

A

E

90
Q

Examples of foods rich in vit E

A

Sunflower seeds
Almonds
Wheat germ

91
Q

Benefits of including healthy fats in diet

A 
Great satiety
Sources of EFAs
Sources of choline
Sources of fat soluble vits/phytonutrients
Greater enhancement in cooked food
92
Q

Sources of healthy fats - fruits

A

Avocado

Olives

93
Q

Sources of healthy fats - seeds

A

Chia
Flax
Pumpkin
Hemp

94
Q

Sources of healthy fats - seed oils

A 
Flax
Hemp
Sunflower
Olive
(ensure cold pressed)
95
Q

Sources of healthy fats - nuts

A

Almonds
Cashews
Walnuts
Brazils

96
Q

Sources of healthy fats - oily fish

A 
Salmon
Mackerel
Anchovies
Sardines
Herring
97
Q

Why is coconut oil a good source of saturated fat?

A

Contains MCTs (ketones/energy)
Contains 50% lauric acid - anti bacterial/viral/fungal
Increases HDL cholesterol
Lowers LDL cholesterol

98
Q

Examples of saturated fats in food

A 
Butyric acid
Caprylic acid
Lauric acid
Palmitic acid
Stearic acid
99
Q

Butyric acid - number of carbons/sources

A

4C
Butter
Dairy
Produced in gut

100
Q

Caprylic acid - number of carbons/sources

A

8C
Coconut oil
Palm kernel
Breast milk

101
Q

What properties does caprylic acid have?

A

Anti-fungal

102
Q

Lauric acid - number of carbons/sources

A

12C

Coconut oil

103
Q

Palmitic acid - number of carbons/sources

A

16C
Coconut oil
Palm oil
Palm kernel

104
Q

Stearic acid - number of carbons/sources

A 
18C
Beef
Pork
Lamb
Cocoa/shea butter
Butter
105
Q

Examples of monounsaturated fats in food

A 
Palmitoleic acid (O7)
Oleic acid (O9)
106
Q

Palmitoleic acid - omega number/sources

A

O7
Coconut oil
Palm kernel
Macadamia nuts

107
Q

Oleic acid - omega number/sources

A 
O9
Olives
Avocado
Nuts - almond, peanut, pistachio, Brazil, pecans
Animal fat
Butter
108
Q

Examples of polyunsaturated fats (O3) in food

A

Alpha-linolenic acid (ALA)
Stearidonic acid (SDA)
EPA/DHA

109
Q

Alpha-linolenic acid (ALA) - sources

A 
Flaxseeds
Chia seeds
Hemp seeds
Dark leafy greens
Pumpkin seeds
Walnuts
110
Q

Stearidonic acid (SDA) - sources

A

Blackcurrant seeds

111
Q

EPA & DHA - sources

A

SMASH fish
Spirulina
Chlorella

112
Q

Examples of polyunsaturated fats (O6) in food

A 
Linoleic acid (LA)
Gamma linolenic acid (GLA)
Arachidonic acid (AA)
113
Q

Linoleic acid (LA) - sources

A 
Safflower
Sunflower
Hemp
Walnut
Pumpkin seeds
Sesame
Almond
Chia
114
Q

Gamma linolenic acid (GLA) - sources

A

Borage oil
EPO
Blackcurrant seed oil

115
Q

Arachidonic acid (AA) - sources

A

Meat
Dairy
Eggs

116
Q

Fats suitable for heating

A

Coconut oil
Butter
Ghee

117
Q

Fats suitable for low temperature cooking

A

EVOO
OO
Avocado oil

118
Q

Fats best suited for using cold

A

Vegetable oils
Flaxseed oil
Hemp oil

119
Q

Why should frying foods in fat be avoided?

A

Promotes free radical formation

120
Q

At what temperature should you not heat oil?

A

180 degrees C

121
Q

Why should polyunsaturated fats not be heated?

A

They oxidise

Produce free radicals

122
Q

How can the oxidisation of PUFAs be avoided?

A

Avoid heating

Store in dark bottles in fridge/freezer

123
Q

When are fatty acids more prone to oxidation?

A

High in polyunsaturated fat
Exposed to heat, light, oxygen
Naturally low in AO
Refined or heavily processed

124
Q

What substances can be created from the oxidation of dietary lipids?

A

Aldehydes
Ketones
Hydrocarbons
Malondialdehyde

125
Q

When is malondialdehyde usually produced?

A

From the oxidation of double bonds

found in polyunsaturated fats

126
Q

Why is malondialdehyde considered dangerous?

A

Potential mutagen

Found in some hydrogenated/overheated fats

Nutrition 1 (Semester II) (16 decks)

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