Lipids Flashcards
What is the % of fat in a lean healthy man vs severe obese
approx 16% compared to 70% mostly in adipocytes
What did the research of Ancel Keys find
High sat fat diet would increase serum cholesterol and lead to heart disease. The American Heart Assoc. then recommended a low fat high carb diet, substituting animal fats for seed oils. This led to into of statins.
Describe WHITE adipose fat and list functions
complex metabolically active endocrine tissue
- secretion of hormones
- growth factors
- enzymes
- protection of organs
- energy storage
- temperature insulation
Lipids exist in various forms, each with different structure and function. Name 4
- individual fatty acids
- triglycerides
- phospholipids (every cell membrane)
- cholesterol (steroid based compounds eg oestrogen)
- Sphingolipids (in nerve cell membranes eg myelin)
- Glycolipids (cell identity)
- cerebrosides (in brain)
- fat soluble vits (ADEK)
List as many function of lipids as you can (up to 10)
- Energy production (1g fat = 9 calories)
- storage of energy reserves (fats more efficient form of storage than carbs or proteins so excess stored as fat)
- cell membrane structure
- Thermal insulation (subcutaneous tissue around organs)
- steroid hormones (e.g. progesterone/oestrogen)
- formation of eicosanoids (signalling molecules involved in processes such as inflammation)
- Growth and development (brain rich in AA/DHA)
- Constitutes nervous tissue structure
- cell to cell signalling
- needed for absorption of ADEK
Describe the chemical structure of fatty acids
hydrocarbon chains with acid group at one end and methyl at other.
How many carbons does a short chain and medium chain fatty acids have, where do they travel to and what are they used for.
Which is useful to take before exercise
Short chain: 5 C
Medium chain: 6-12 Cs
Travel to liver used to create energy or ketones.
MCTs good source of energy before exercise (1tbs)
How many carbons does a long chain and very long chain fatty acid have and what are they used for
14-22 C and more than 22 Cs
Build cell membranes
How are SCFAs produced by the body
by dietary fibre fermenting in the COLON
Name the most common SCFAs
Acetate
Propionate
Butyrate
Which fatty acid is important for colon health and why
BUTYRATE
- supports intestinal tight junctions
- anti-inflammatory effect on the colon
How are fatty acids named
Using their common names and the omega nomenclature system
- Omega system: number of carbon atoms, number of double bonds, number of carbons from the omega end to the first carbon in the double bond.
How do unsaturated fats become saturated
with the addition of a hydrogen - hydrogenation, which turns the natural fatty acid into unnatural forms (trans)
Describe the composition of a saturated fatty acid (e.g. how many c-c double bonds)
no C-C double bonds. All carbons are completely saturated with hydrogen bonds.
Solid at room temperature
Describe the composition of unsaturated fatty acids
one or more double bonds between carbons. Liquid at room temp
Describe the composition of monounsaturated fatty acids
one double bond in the chain
Describe the composition of PUFAs
several double bonds in the
What is the result of an increasing number of double bonds in a fatty acid
the more double bonds the less stable and increasing susceptibility to oxidation
What do trans fats do to blood triglyceride and cholesterol profiles and what disease states are they linked to
alter blood triglyceride and cholesterol profiles - linked to CVD, insulin resistance and cancer.
Explain the configuration of a CIS fatty acid
H atoms are on the same side of the double bond
explain the configuration of a TRANS fat
H atoms are on separate sides of the double bond
are trans fats saturated or unsaturated
unsaturated but behave like saturated fats because of their unkinked shape
Name a natural trans fat
CLA - conjugated linoleic acid found in grass fed meat and dairy. Could increase lean muscle mass and decrease body fat.
Triglycerides: major form of dietary fat and storage form. Describe their structure
1 glycerol and three fatty acids.
The fatty acids can differ in length (number of C atoms) and degree of saturation (no. of hydrogen molecules attached)
What disease state is a high level of triglycerides linked to
atherosclerosis - heart disease and stroke
When does the body synthesise triglycerides
what is the process called
where are they taken up
- when caloric intake exceeds energy requirements
- Excess energy is converted to triglycerides via lipogenesis in the liver and adipose tissue
- taken-up by adipose tissue
Where do adipocytes acquire triglycerides from
circulating lipoproteins, chylomicrons and VLDL
What is lipogenesis
The process of converting acetyl-CoA to triglycerides for storage in fat
when are fatty acids synthesised
when there is an excess of carbohydrates
what is acetyl-CoA formed from and how does it form palmitic acid
from glucose during glycolysis, as well as from fats and amino acids
- 2 carbon units are added to form palmitic acid (C16)
- 3 fatty acids are bound to glycerol and stored as triglycerides
where in the body does fatty acid synthesis take place
in the liver, adipocytes, kidneys, lactating mammary glands
LIPOLYSIS - when does it take place and what happens
When dietary energy in limited triglycerides are hydrolysed by LIPASE into fatty acids and glycerol for use in the body
What hormones stimulate lipolysis and what hormone antagonises the lipolytic effect of these hormones
- adrenaline and noradrenaline (stress)
- adrenocorticotropic hormone (ACTH)
- Glucagon and growth hormones
- TSH and thyroxine
Antagonised by insulin which leads to disregulated breakdown of triglycerides which congregate in central adipose tissue/visceral fat which is metabolically active, secreting inflammatory cytokines and creating cycle of insulin resistance
Describe the process of fatty acid catabolism to produce ENERGY
- CARNITINE facilitates the transport of fatty acids across the mitochondrial membrane.
- fatty acids undergo BETA OXIDATION and are broken down into 2-carbon blocks as ACETYL -CoA
- Acetyl Co-A is oxidised via the krebs cycle to CO2 and H2O.
- energy created in electron transport chain
KETOSIS when does it take place
when carbohydrate levels are low (below 40g/day), fat becomes the primary fuel for energy production rather than glucose. Ketones are synthesised as they can cross the BBB. Happens during periods of fasting
what is ketogenesis
acetyl-CoA is converted to
acetoacetate
b-hydroxybutyrate
acetone - which gives the sweet smell to breath
what are the health benefits of ketosis
weight loss, epilepsy management, parkinson, alzheimers
what is ketoacidosis
dangerous condition where there’s insufficient pancreatic insulin to regulate B-hydroxybutyrate (remember, insulin is antagonist to lipolysis; therefore uncontrolled breakdown of lipids leading to acidity)
How can we optimise the digestion of lipids
- chew and don’t drink with meals
- increase bile production and stomach acid levels, bitter foods. reduce stress
- Choleretics (increase bile production); cholagogues (Increase bile flow) eg dandelion, turmeric)
- increase glycine and taurine (components of bile) in legumes, spinach and eggs
-Olive oil can stimulate bile secretion
Lipid digestion - Explain the process of triglyceride digestion and the key enzymes needed
Glycerol separated from fatty acids by:
- gastric lipase (stomach)
- pancreatic lipase (duodenum)
Bile emulsifies fat, increasing surface area of droplets.
the free fatty acids and glyceride are transported to enterocytes where rebuilt and packaged into CHYLOMICRONS and transported via lymphatic system to the bloodstream.
Fatty acids are used or stored in adipose tissue
Lipid recommendations: What % of total energy should
TOTAL fat be
SATURATED fat
PUFA
Omega 3
Total : 20-35% (44-78g based on 2k cal)
Saturated : no more than 10% (22g)
PUFA: 6-11% (13-24g)
Omega: .5-2% (1.1-1.4g)
What does the UK Government Scientific Advisory Committee on Nutrition advise regarding fat intake
Sat fat not to exceed 10% dietary intake of energy
Low fat dairy (oft high in sugar)
unsaturated oils and spreads (refined and trans fats)
NO emphasiss on healthy fats (fish, avocado, nuts, seeds, EVOO, egg yolk, grass fed meat)
Without adequate energy from fat, people aren’t satiated. What did the PURE 2017 study find regarding mortality and fat consumption
people consuming more than 35% of daily energy in fat less likely to die than those consuming 10%
List benefits of including healthy fats in diet (eg mix of mono, poly and sat fats including fat soluble vits such as E)
greater satiety
sources of EFAs
Choline (to synthesise phospatidylcholine)
source of ADEK and phytonurients
greater flavour enhancement of cooked food
List food sources of healthy dietary fats
fruit - avo, olives
seeds - chia, flax, hemp, pumpkin
nuts - almonds, brazils, walnuts
COLD PRESSED seed oils - flax, chia, olive, sunflower
Oily fish - SMASH
Saturated fats : how does the body use the MCT (medium chain triglycerides) in coconut oil
Name the fat contained in 50% of coconut oil and its benefits
What diseases do they potentially help
as a source of fuel, or turns them into ketones.
MCTs increase the number of calories burned compared to longer chain fatty acids
Lauric acid, which can form monolaurin. Both are antebacterial, antiviral, antifungal.
Increase HDL and lower LDL
Positive outcomes in epilepsy, and alzheimers
Name the SATURATED fats and the food they’re found in
Butyric acid (4C) - dairy. produced in gut
Caprylic acid (8-c) - coconut, palm kernal, breast milk. Antifungal
Lauric acid (12-c) - coconut
Palmitic acid - coconut, palm, palm kernal
Stearic acid (18-c) - beef, pork, lamb, cocoa, shea butter and butter
Name the MONOunsaturated fats and foods found in (x2)
Palmitoleic acid Omega 7: coconut, palm kerbal, macadamia nuts
Oleic acid omega-9: olive, avocado, almond, peanut, pistachio, brazil, pecan, cashew, animal fat, butter, hazlenut, neem, macadamia
Name the POLYUNSATURATED FATS and food sources
OMEGA 3
ALPHA- LINOLENIC ACID ALA)
flaxseed (richest source), chia, hemp, dark green leaves, Pumpkin seed, rapeseed, walnuts
STEARIDONIC ACID (SDA)
Blackcurrent seed
EPA and (20 C, 5 dble bonds)
DHA (22 C, 6 dble bonds)
oily fish
spirulina and chlorella
DHA - marine algae
OMEGA 6
LINOLEIC ACID
Sunflower, hemp, soybean, walnut, avocado, brazilnut, pumpkin seed, chia, almond
GAMMA LINOLENIC ACID
evening primrose, borage oil, blackcurrent seed
ARACHIDONIC ACID
meat and animal products
name fats that can tolerate being heated and are preferable for cooking and why
coconut, ghee, butter - saturated.
More stable due to lack of double bonds
why should you avoid frying foods
free radical formation
How should monounsaturated fats be used for cooking and name some
extra virgin olive oil, avocado oil - not about 180; oxidise at higher temps but naturally occuring anti oxidants make them safer to use
how should polyunsaturated fats be used during cooking and name two
veg and flaxseed oils
oxidise when heated and produce free radicals, so only used in raw cold pressed form
store in dark bottles in fridge or freezer
Look for pressing and used by date
How do the fatty acids within triglycerides and unsaturated fatty acids go rancid
Fatty acids within triglycerides go rancid by releasing the fatty acids from glycerol
Unsaturated fatty acids within the triglycerides go rancid when the double bonds are oxidised
What makes fats more prone to oxidation
if high in PUFA
exposed to prolonged heat light or O2
naturally low in antioxidants
refined or heavily processed.
What products are formed from fat breakdown and rancidity.
What is generally formed from the oxidation of the double bonds in lipids
aldehydes, ketones, hydrocarbons
MALONDIALDEHYDE - it’s a mutagen found in hydrogenated or overheated fats.
What is the name of the enzyme that catalyses the chemical reaction to produce GLA and EPA from ALA and LA
Delta-6-desaturase
What is the ratio of Omega 6:3 in a western diet
16:1
Why are EPA and DHA considered conditionally essential nutrients
due to the low conversion of ALA to EPA and DHA
what is the recommended weekly intake in mg of EPA/DHA and how can it be achieved
250mg
2-3 portions of oily fish or algal source
List functions of EFAs
maintain cell membrane fluidity, including organelle membranes
act with cell membrane proteins affecting transport of substances in and out of cell
cell to cell communication
foetal and child BRAIN development
precursor of eicosanoids (local hormones)
List clinical indicators of low EFAs
Skin
Endocrine
Reproductive system
circulatory
muscoskeletal
immune
neurological
Skin: dry, flaky, chapped lips. Hyperkeratosis pilaris. delayed healing, dry brittle nails, acne, eczema, dermatitis, dry oily hair
Endocrine: weight imbalance, PMS, hyperinsulinaemia
Reproductive: infertility, miscarriages, ovarian cysts
circulatory: frequent nosebleeds, bleeding gums, easy bruising
Muscoskeletal: chronic joint pain/artiritis, delayed injury recovery
Immune: susceptibility to infections
Neurological: demential, alzheimers, parkinson, irritability, tingling, CFS
Omega 3 - alpha linolenic acid. name food sources and how many carbons
flaxseeds, hemp seeds, soybeans, walnuts, dark green leaves
18 carbon
List therapeutic uses of ALA
CVD - decrease risk of atherosclerosis; reduce C reactive protein levels; anti arrhythmic effect; anti-hypertensive - lowers activity of ACE (angiotensin converting enzyme); lowers LDL
Neurological: INCREASES BDNF (brain derived neurotropic factor… neuroprotective): BDNF supports strokes, promotes vasodilation in the brain; BDNF supports depression learning and memory
Anti-inflammatory: helpful in IBD, asthma and autoimmune conditions. But needs to be converted to EPA and DHA
What are the drug interactions of ALA
it’s anti-coagulant. blood thinning meds eg warfarin and aspirin
cholesterol lowering meds (statins) - may have agonist effect when combined with statins
Therapeutic uses of EPA and DHA x4 and supplemental dosage
CVD:
supplementation can significantly reduce blood triglyceride levels; lower BP; preventative against atherosclerosis and lowers blood fibrinogen levels. DART trial showed reduction in myocardial reinfarction after daily 900mg EPA/DHA
DOSAGE: 0.8 - 3g/day
Anti-infammatory:
inhibit NFkB, TNF-a and Interleukin-6. useful for arthritis, IBD, eczema, SLE.
>2.7g/day fish oils lowers NSAID use in arthritis people
DOSAGE: EPA 3-5g/day
`DHA 0.8-2.7g/day
Neurological health:
neuroprotective properties and increase BDNF. Lower levels associated with learning and behavioural problems.
Depression ADHD, alzheimers
DOSE:
EPA 0.6-3g
DHA 0.15-2g/day
Foetal health:
foetal brain development. Supplementation in pregnancy may protect children against allergies
DOSE: EPA 800mg/day
DHA 400mg/day
Can a vegetarian diet meet EPA/DHA needs
yes by including good sources of ALA - flax/hemp seed
Support conversion by increasing enzyme co-factors (Zn, Mg, B6)
Moderate Omega 6
Algal EPA/DHA supps
What might determine the quality of vegan omega oil quality
use of water extraction methods to provide DHA
Free from carrageenan which may induce inflammation in colonic cells
cold pressed, organic
what might determine the quality of omega fish oil
sustainability practices
independently tested for purity and toxins
EPA and DHA content should be listed
OMEGA 6
Linoleic Acid (LA)
what is the configuration
18:2 n-6
Name food sources of LA
safflower, veg oils, sunflower, soybean, corn oils, nuts, seeds, some vegetables
What vits/minerals does the conversion of LA to GLA require
C, B3, B6, Mg, Zn
Why are flax and hemp seeds considered nutritionally superior to safflower?
they also contain omega 3 as well as 6
Gamma-linolenic acid (GLA)
what is the configuration
18:3 n-6
what are the main food sources of GLA
evening primrose oil, borage oils, hemp, blackcurrant seed oil
List three therapeutic uses of GLA
Rheumatoid artirhtis
reduces pain, swelling and morning stiffness.
DOSEAGE: 1.4g/day of borage seed oil
ADHD: with EPA shows improvements in impulsiveness and attention
Eczema: reduced inflammation - improves skin symptoms
DOSAGE: 320mg GLA/day BUT be careful not to raise levels of AA
List therapeutic uses of Evening Primrose Oil and which omega is it abundant in
Linoleic Acid (but also contains GLA)
PMS: GLA is precursor to PG1 which inhibits prolactin (high in women with PMS)
DOSE: 1500mg/day for 3 months
Cyclical mastalgia (breast pain): GLA forms PG1 which inhibits the synthesis of AA metabolites (therefore anti-inflammatory)
DOSE: 1000mg 3x daily 4-6 months
Female fertility: increases and optimises cervical mucus to sustain sperm during conception
DOSe: 1500-2000mg daily from day 1 of menses
Name drug interactions of GLA
Ceftazidime - may increase effectiveness
Chemo - increase treatment effects
NSAIDs - counteract effects of GLA
Arachidonic Acid (AA) where is it predominantly found
animal products, meat eggs dairy, esp when fed grain
Arachidonic acid is seen as inflammatory. However, there are benefits and ways it which it is controlled. Explain…
What does PG2 do
Inflammation is an important part of the immune system’s response to injury and infection.
AA is metabolised by COX-1 and LOX-2 enzymes to prostaglandin series 2 (PG2).
PG2 causes inflammatory effects e.g. fever, vascular permeability, vasodilation, pain and oedema.
To prevent excess inflammation, PG2 induces 15-LOX activity that leads to formation of anti inflammatory lipoxins
What are Eicosanoids (name some) and what are they formed from
formed from the oxidation of Omega 3 and 6 fats.
Locally acting hormone-like signalling molecules.
They include prostaglandins, leukotrienes, thromboxanes, resolvins and protectins
What functions are eicosanoids involved in
Can be both pro and anti inflammatory
Inflammation
BV permeability and constriction
blood coagulation
Immune cell behaviour
lipid accumulation
CNS signalling
How are eicosanoids formed; name the enzyme needed; what EFAs can they be made from
fatty acids are released from the membrane phospholipids by enzyme PHOSPHOLIPASE A2
COX and LOX convert them to eicosanoids (and then leukotrienes / prostaglandins etc depending on the starting fatty acid)
Made from AA, EPA DGLA
Prostaglandins, made from eicosanoids, fall into three families/series, depending on which fatty acid they are made from.
Name which fatty acid Series 1 prostaglandin (PG1) is made from; is it pro or anti inflammatory, and its key functions
DGLA (dihomo-y-linolenic acid)
ANTI inflammatory
keeps blood platelets from sticking together
removes excess sodium and water from the body
relax blood vessels promoting circulation
Prostaglandins, made from eicosanoids, fall into three families/series, depending on which fatty acid they are made from.
Name which fatty acid Series 2 prostaglandin (PG2) is made from; is it pro or anti inflammatory, and its key functions
AA
PRO inflammatory
promotes platelet aggregation
promotes sodium and water retention (increase BP)
oppose functions of PG1)
Prostaglandins, made from eicosanoids, fall into three families/series, depending on which fatty acid they are made from.
Name which fatty acid Series 3 prostaglandin (PG3) is made from; is it pro or anti inflammatory, and its key functions
EPA
ANTI inflammatory
some have weak platelet aggregating properties
prevent release of AA from cell membranes
EPA is the most important factor limiting PG2 production
How do the eicosanoids/prostaglandins work together to control inflammation
PG2 (Eicosanoids from from Arachidonic Acid) produce initial inflammation. This is shut off by eicosanoids made from DGLA and EPA - PG1 and PG3
Why must the omegas be balanced
because the most abundant will occupy the enzyme active site, determining which prostaglandins will predominate. e.g. high AA = high PG2 = pro inflammatory.
High EPA/DHA = immune suppression
Which Omega fatty acids can be affected by genetic variability
EPA and DHA
Polymorphisms are common in the genes coding for delta-6 and delta-5 desaturase. These are needed for the conversion of LA and ALA
What factors/minerals might inhibit delta-6-desaturase and delta-5-desaturase
zinc, stress, insulin resistance, alcohol
What are the common EFA tests
Omega-3 index: a marker for CV risk
Omega 6:3 ratio: a marker for chronic illness
AA:EPA ratio : a marker of ‘silent’ inflammation
How can Omega 6:3 ratio be balanced with supplementation
supplement with EPA/DHA and address co-factor deficiencies needed for interconversion.
List fatty acid profile tests
Genova - EFA and metabolic fatty acids (blood test)
Wiley’s Finest - omega-3 index test (blood spot)
Igennus - Opti-O-3 (blood spot)
What is cholesterol essential for the synthesis or action of
Important for cell structure and function.
Vitamin D and Ca metabolism
Cortisol and related hormones
Alsosterone - for mineral and fluid balance
sex hormones
bile salts and acids
membrane integrity - esp the brain
Lipoproteins - needed for triglyceride and cholesterol transport.
Where is cholesterol synthesised and excreted
DIETARY CHOLESTEROL DOESN’T MAKE A BIG DIFFERENCE IN PLASMA CHOLESTEROL LEVELS….
a triglyceride rich diet IS MORE PROBLEMATIC and stimulates cholesterol synthesis in the LIVER and SMALL INTESTINE, whereas dietary cholesterol is only partially absorbed.
Excreted in the stool intact, mostly as bile products
What factors can help control levels of dieatry cholesterol
Fibre/non-digestible carbs increases the excretion of cholesterol
healthy microbes metabolise cholesterol leading to less reabsorption.
DIETARY CHOLESTEROL DOES NOT SIGNIFICANTLY AFFECT plasma cholesterol levels - its genetics and other nutritional factors such as high triglycerides
Explain what HDL, LDL and VLDL are
they are lipoproteins, carriers of cholesterol and substances such as CoQ10, beta-carotene, Vit E.
LDL - takes cholesterol from liver to cells
VLDL - takes triglycerides to cells
HDL - carries cholesterol from cells back to liver
How has the belief that cholesterol causes heart attacks been challenged
2009 study found ‘bad’ cholesterol was lower in people with heart disease
Over 10 years the % of men aged 65-74 with high cholesterol dropped from 87-54 whilst CHD remained at 20%
What is the definition of low plasma cholesterol
it was 6.5 mmol/L but in 2004 dropped to below 5 mmol/L
What is the role of cholesterol in atherosclerosis
Atherosclerosis is an inflammatory disease - no inflammation or injury to the endothelium, cholesterol doesn’t deposit. Look at high blood pressure or diabetes etc causing damage in the first place.
LDL cholesterol deposits in arterial wall and becomes oxidised.
Which is a better means of measuring LDL - total cholesterol or measuring particle size
measuring particle size.
LDL: If LDLs are small and dense, 3x greater risk of coronary artery disease. Large and fluffy may be protective
HDL: larger HDLs more effective at removing cholesterol from blood and promote NO production in endothelial cells - anti-inflammatory and anti-thrombotic
What might an increase in cholesterol indicate
A greater demand for cholesterol’s anti inflammatory function/need to repair cell membranes/make hormones etc.
Cardiovascular markers. Explain the below:
Lipoprotein (a)
Lp-PLA2
Fibrinogen
C-reactive protein
Lipid peroxides
Lipoprotein (a): blood clotting agent. Key genetic risk factor in coronary artery disease.
Lp-PLA2: enzyme that plays a role in endothelial inflammation and atherosclerosis
Fibrinogen: raised levels are risk for clot formation
C-reactive protein: Inflammatory marker associated with CVD
Lipid peroxides: raised levels reflect oxidative damage to membranes.
List cardiovascular markers
Lipoprotein (a)
Lp-PLA2
Fibrinogen
C-reactive protein
Lipid peroxides
What are the ranges for serum cholesterol and triglycerides in GP tests
Serum cholesterol above 5 mmol/L = statins prescribed
Triglycerides optimal range is 0.79-1.24 mmol/L
PHOSPHOLIPIDS/PHOSPHATIDES - structural basis of all cell membranes. What are they made up of and name three
Phosphatides: contain glycerol and 2 longchain fatty acids.
Inositol
choline
serine
What is the role of lecithin
A group of fats, main source of choline. Synthesised by the liver and plays role in emulsification (fat digestion), increases solubility of cholesterol, improves cognitive function. Used to treat high cholesterol.
Inositol is a key phospholipid - name therapeutic uses
Improves insulin sensitivity - used for insulin resistance, T2DM, PCOS, anxiety, chronic fatigue
Phosphatidylserine is a key phospholipid - name therapeutic uses
Improves neuronal membrane functioning and cognitive function. Can be used for depression, insomnia, stress.
Phosphatidylcholine is a key phospholipid - name therapeutic uses
neuro- and hepato-protective. Supplies choline for the synthesis of the neurotransmitter acetylcholine.
Memory, cognition, immunity, hormone function.
Name two foods containing the fat soluble vitamin E
Sunflower seeds
Almonds
