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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
When are SCFAs produced?
When dietary fibre is fermented in the colon
26
Examples of common SCFAs
Acetate Butyrate Propionate
27
What is butyrate important for?
Colon health - primary energy source for colonocytes Supports intestinal tight junctions Anti-inflammatory properties
28
What is the naming structure of fatty acids?
Number of carbon atoms Number of double bonds Number of carbons from the omega end to first carbon at a double bond
29
How do unsaturated fats become saturated?
By the addition of a hydrogen | as in hydrogenation when oils are made into solid spreads
30
What does hydrogenation do?
Turns a natural fatty acid into an unnatural form | damaging to health
31
What are saturated fatty acids?
Contain no carbon double bonds All the carbons are completely saturated with hydrogen bonds Solid at room temperature
32
What are unsaturated fatty acids?
Contain one or more double bonds between carbons | Liquid at room temperature
33
What are monounsaturated fatty acids?
Have one double bond in the chain
34
What are polyunsaturated fatty acids?
Have several double bonds in the chain
35
What impact does the number of double bonds have on the fatty acid?
The more double bonds there are, the less stable it is | Increases susceptibility to oxidation
36
How are trans fats produced?
High temperatures | Hydrogenation
37
What products are trans fats found in?
Margarine Processed foods Refined veg oils
38
Why are trans fats bad for cell membranes?
Stiffens them Makes them prone to oxidation Alters their protective action/permeability
39
What diseases are trans fats linked to?
CV disease Insulin resistance Cancer
40
Are the majority of natural fats cis or trans?
Cis
41
What is conjugated linoleic acid (CLA)?
A natural trans fat found in grass-fed meat and dairy products
42
What are the benefits of CLA?
Helps increase lean muscle mass | Helps decrease body fat
43
Why are trans fats unsaturated but behave like saturated fats?
Because they don't kink
44
What type of fat is the major form of dietary fat?
Triglycerides
45
Which type of fat is the fat that is stored in the body and circulated in the blood when released for energy?
Triglycerides
46
How are triglycerides chemically constructed?
Lipid molecules | 1 unit of glycerol and 3 x fatty acids
47
How can the three fatty acids differ?
``` In length (number of carbon atoms) Degree of saturation (number of hydrogen molecules attached) ```
48
Which pathology has high levels of triglycerides in the blood been linked to?
Atherosclerosis
49
When does the body synthesise triglycerides?
Whenever calorific intake exceeds energy requirements
50
What process is utilised to convert excess dietary energy to triglycerides?
Lipogenesis
51
Where is excess digested fat deposited?
Adipose tissue
52
Where does lipogenesis take place?
Adipose tissue | Liver
53
How do adipocytes acquire triglycerides?
From circulating lipoproteins, chylomicrons, VLDL | via blood vessels
54
What happens during lipogenesis?
Acetyl-CoA is converted to triglycerides for storage in fat
55
When are fatty acids synthesised?
When there is an excess of carbohydrates
56
How is acetyl-CoA built up?
With 2 carbon units to produce palmitic acid
57
Where does fatty acid synthesis take place?
Liver Adipocytes Kidneys Lactating mammary glands
58
What is lipolysis?
The breakdown of triglycerides for energy
59
What happens during lipolysis?
The fatty acids from triglycerides hydrolysed by lipase and released from adipocytes into circulation
60
What is lipolysis stimulated by?
Adrenaline/noradrenaline (when stressed) Adrenocorticotropic hormone (ACTH) Glucagon and growth hormone Thyroid stimulating hormone/thyroxine
61
What affect does insulin have on the hormones that stimulate lipolysis?
It has an antagonistic effect | so insulin resistance = lipogenesis = central adiposity
62
What happens when fatty acids are broken down to create energy?
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
Which amino acid facilitates the transport of fatty acids across the mitochondrial membrane?
Carnitine
64
When does fat become the primary fuel for energy?
When carb levels are low
65
What are produced for energy when glucose is in short supply?
Ketones
66
When are ketones usually produced?
Overnight During dieting During fasting
67
What is ketogenesis?
The process of making ketones
68
What happens during ketogenesis?
Acetyl-CoA is converted to ketones
69
Which ketones are produced during ketogenesis?
Acetoacetate | Beta-hydroxybutyrate
70
Which ketone can acetoacetate produce?
Acetone
71
How does acetoacetate convert to acetone?
Via decarboxylation | removal of a carboxyl group
72
What characteristic does acetone have?
Pear drop smell to breath
73
How many grams of carbs a day is needed to reach ketosis?
No more than 40g
74
Which pathologies have seen benefits via a low carb diet?
Weight loss Epilepsy Parkinson's AZD
75
What is the build up of acetone in the body called?
Ketoacidosis
76
What is ketoacidosis?
Dangerous condition that occurs when there is insufficient pancreatic insulin to regulate serum beta-hydroxybutyrate
77
Which enzymes, and where, aid the digestion of triglycerides?
Gastric lipase - stomach | Pancreatic lipase - duodenum
78
Which substance, along with lipases, facilitates the breakdown of lipids?
Bile
79
What happens to triglycerides in the body once they are broken down?
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
How to optimise lipid digestion
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
How can bile production be increased?
Bitters B6/zinc rich foods Choleretics - dandelion, artichoke, turmeric Stress management
82
How can bile flow be supported?
Good hydration | Cholagogues - dandelion, artichoke, turmeric
83
How can bile secretion be stimulated?
Olive oil
84
How many grams of total, saturated, polyunsaturated and O3 fats are recommended for a female consuming 2000kcals per day?
Total: 44-78g Saturated: 22g (10% of energy) Polyunsaturated: 13-24g O3: 1.1-4.4g
85
What does the Eatwell Guide recommend in terms of fat consumption?
Choose low fat dairy | Unsaturated oils/spreads (eaten in small amounts)
86
Why are the Eatwell Guide recommendations flawed?
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
What did the PURE study of 2017 found regarding high carb/high fat diets?
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
Which fats should we have in the diet?
Natural, unrefined Saturated Monounsaturated Polyunsaturated
89
Which vitamin is important to consume when including fats in the diet?
E
90
Examples of foods rich in vit E
Sunflower seeds Almonds Wheat germ
91
Benefits of including healthy fats in diet
``` Great satiety Sources of EFAs Sources of choline Sources of fat soluble vits/phytonutrients Greater enhancement in cooked food ```
92
Sources of healthy fats - fruits
Avocado | Olives
93
Sources of healthy fats - seeds
Chia Flax Pumpkin Hemp
94
Sources of healthy fats - seed oils
``` Flax Hemp Sunflower Olive (ensure cold pressed) ```
95
Sources of healthy fats - nuts
Almonds Cashews Walnuts Brazils
96
Sources of healthy fats - oily fish
``` Salmon Mackerel Anchovies Sardines Herring ```
97
Why is coconut oil a good source of saturated fat?
Contains MCTs (ketones/energy) Contains 50% lauric acid - anti bacterial/viral/fungal Increases HDL cholesterol Lowers LDL cholesterol
98
Examples of saturated fats in food
``` Butyric acid Caprylic acid Lauric acid Palmitic acid Stearic acid ```
99
Butyric acid - number of carbons/sources
4C Butter Dairy Produced in gut
100
Caprylic acid - number of carbons/sources
8C Coconut oil Palm kernel Breast milk
101
What properties does caprylic acid have?
Anti-fungal
102
Lauric acid - number of carbons/sources
12C | Coconut oil
103
Palmitic acid - number of carbons/sources
16C Coconut oil Palm oil Palm kernel
104
Stearic acid - number of carbons/sources
``` 18C Beef Pork Lamb Cocoa/shea butter Butter ```
105
Examples of monounsaturated fats in food
``` Palmitoleic acid (O7) Oleic acid (O9) ```
106
Palmitoleic acid - omega number/sources
O7 Coconut oil Palm kernel Macadamia nuts
107
Oleic acid - omega number/sources
``` O9 Olives Avocado Nuts - almond, peanut, pistachio, Brazil, pecans Animal fat Butter ```
108
Examples of polyunsaturated fats (O3) in food
Alpha-linolenic acid (ALA) Stearidonic acid (SDA) EPA/DHA
109
Alpha-linolenic acid (ALA) - sources
``` Flaxseeds Chia seeds Hemp seeds Dark leafy greens Pumpkin seeds Walnuts ```
110
Stearidonic acid (SDA) - sources
Blackcurrant seeds
111
EPA & DHA - sources
SMASH fish Spirulina Chlorella
112
Examples of polyunsaturated fats (O6) in food
``` Linoleic acid (LA) Gamma linolenic acid (GLA) Arachidonic acid (AA) ```
113
Linoleic acid (LA) - sources
``` Safflower Sunflower Hemp Walnut Pumpkin seeds Sesame Almond Chia ```
114
Gamma linolenic acid (GLA) - sources
Borage oil EPO Blackcurrant seed oil
115
Arachidonic acid (AA) - sources
Meat Dairy Eggs
116
Fats suitable for heating
Coconut oil Butter Ghee
117
Fats suitable for low temperature cooking
EVOO OO Avocado oil
118
Fats best suited for using cold
Vegetable oils Flaxseed oil Hemp oil
119
Why should frying foods in fat be avoided?
Promotes free radical formation
120
At what temperature should you not heat oil?
180 degrees C
121
Why should polyunsaturated fats not be heated?
They oxidise | Produce free radicals
122
How can the oxidisation of PUFAs be avoided?
Avoid heating | Store in dark bottles in fridge/freezer
123
When are fatty acids more prone to oxidation?
High in polyunsaturated fat Exposed to heat, light, oxygen Naturally low in AO Refined or heavily processed
124
What substances can be created from the oxidation of dietary lipids?
Aldehydes Ketones Hydrocarbons Malondialdehyde
125
When is malondialdehyde usually produced?
From the oxidation of double bonds | found in polyunsaturated fats
126
Why is malondialdehyde considered dangerous?
Potential mutagen | Found in some hydrogenated/overheated fats

Nutrition 1 (Semester II) (16 decks)

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