Download Lipids and Cardiovascular Disease

Chapter 5
LIPIDS
Fat in the Canadian Diet
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The Canadian Community Health Survey (CCHS)
revealed:
 Fat in the Canadian diet declined from 40% in 1978 to
31% in 2004.
 Intake of fat above 35%/day’s kcal is most common in
the 35 to 50 year age group.
 50% of Canadians’ fat intake comes from two of the
food groups: meat & alternatives (31.6%) and milk &
alternatives(17.9%).
 25% of fat comes from fast foods and snack foods
(baked goods).
Copyright 2012, John Wiley & Sons Canada, Ltd.
Lipids
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Lipid is the chemical term for fat.
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Lipids contribute texture, taste, flavor and
aroma to foods.
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Fats and oils contain 9 calories per gram.
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Fat Intake Affects Health
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Triglycerides
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Triglycerides are the major form of lipid in
food and in the body.
Triglycerides consist of three fatty acids
attached to a glycerol molecule.
If only one fatty acid is attached to the
glycerol it is called a monoglyceride.
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Triglycerides
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Fatty Acids
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The carbon chains of fatty acids vary in length from
a few to 20 or more carbons.
Short-chain fatty acids range from 4-7 carbons and
remain liquid at room temperature.
Saturated fatty acids contain carbons in a chain that
are bound to two hydrogens.
Unsaturated fatty acids contain some carbons that
are not saturated with hydrogens.
Omega-3 and omega-6 fatty acids are unsaturated
fatty acids.
Coconut oil is a medium chain fatty acid.
Most animal fats contain saturated fatty acids.
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Fatty Acids
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Omega-3 and Omega-6 Fatty Acids
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Trans Fatty Acids
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Trans fatty acids can be created by
hydrogenation.
Hydrogenation causes some double bonds to
become saturated.
Hydrogenated fats can be found in
margarines, vegetable shortening and shelfstable baked goods.
Trans fatty acids have be shown to raise
blood cholesterol levels and increase the risk
of heart disease.
Copyright 2012, John Wiley & Sons Canada, Ltd.
Fatty Acids in Food
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Phospholipids
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Phospholipids are lipids attached to a
phosphate group.
Phosphoglycerides are the major class of
phospholipids.
Phosphoglycerides can act as emulsifiers.
Phosphoglycerides form a lipid bilayer in
membranes, helping to regulate what can
pass into and out of a cell.
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Phospholipids
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Sterols
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Sterols are a type of lipid found in plants and animals.
Sterols do not dissolve in water.
Cholesterol is a type of sterol found only in animals.
90% of cholesterol in the body is found in cell
membranes.
Diets high in cholesterol (from animals) can increase the
risk of heart disease.
Plant sterols can help reduce cholesterol in the body.
Copyright 2012, John Wiley & Sons Canada, Ltd.
Lipoproteins
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Lipoproteins are transport particles for waterinsoluble lipids.
Lipoproteins are created by combining waterinsoluble lipids, phospholipids and proteins.
Lipoproteins help transport triglycerides,
cholesterol and fat-soluble vitamins from the
small intestine and stored lipids from the liver.
Copyright 2012, John Wiley & Sons Canada, Ltd.
Lipoproteins
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Chylomicrons
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Chylomicrons are a combination of
triglycerides, cholesterol, phospholipids and a
small amount of protein.
Chylomicrons help to transport long-chain
fatty acids into the lymphatic system and into
the blood stream without passing through the
liver.
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Chylomicrons
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Low-Density Lipoproteins
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The liver is the major lipid-producing organ in
the body.
Triglycerides produced in the liver are
incorporated into entities called very-lowdensity lipoproteins (VLDLs).
VLDLs transport lipids out of the liver and
deliver them to cells in the body.
The enzyme lipoprotein lipase removes
triglycerides from VLDLs, creating
intermediate-density lipoproteins (IDLs).
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Low-Density Lipoproteins
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Approximately two-thirds of IDLs return to the liver;
the remainder are transformed in the blood into
low-density lipoproteins (LDLs).
LDLs contain less triglyceride and more
cholesterol than VLDLs. LDLs deliver cholesterol
to the cells.
If the amount of LDL cholesterol in the blood
exceeds the amount that can be used by the cells,
the result is a high level of LDLs.
High levels of serum LDLs have been associated
with an increased risk for heart disease.
Copyright 2012, John Wiley & Sons Canada, Ltd.
High-Density Lipoproteins
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Most cells cannot break down cholesterol.
Cholesterol is returned to the liver to be eliminated from
the body.
This reverse cholesterol transport is done by highdensity lipoproteins (HDLs).
High levels of HDL in the blood help to prevent
cholesterol from depositing in the artery walls.
High levels of HDL are associated with a reduction in
heart disease risk.
Copyright 2012, John Wiley & Sons Canada, Ltd.
Lipid Functions in the Body
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Most lipids in the body are triglycerides
stored in adipose tissue.
Deposits of adipose tissue help to define
body shape, provide stored energy, insulate
the body from temperature changes and
protect internal organs against physical
shock.
Lipids in the body are important for lubricating
body surfaces, such as the mucous
membranes of the eyes.
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Lipid Functions in the Body
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Cholesterol is used to make several
hormones, including estrogen and
testosterone.
PUFAs help to regulate blood pressure and
blood clotting.
Essential fatty acids are important for growth,
skin integrity, fertility and the structure and
function of cell membranes.
Copyright 2012, John Wiley & Sons Canada, Ltd.
Lipid Functions in the Body
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Eicosanoids are made from omega-3 and
omega-6 fatty acids. Eicosanoids help
regulate blood clotting, blood pressure and
immune function.
Fatty acids and glycerol can be used to
produce energy in the form of ATP.
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Lipids Can Be Used to Produce
Energy in the Body
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Essential Fatty Acid Deficiency
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If adequate amounts of essential fatty acids
are not consumed, a deficiency can result.
Symptoms include: dry, scaly skin, liver
abnormalities, poor wound healing, growth
failure in infants and impaired hearing and
vision.
Copyright 2012, John Wiley & Sons Canada, Ltd.
Lipids and Cardiovascular Disease
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In 2007, cardiovascular disease killed 73,000
Canadians, making it the leading cause of death and
accounting for 30% of deaths in Canada that year.
Cardiovascular disease is the number one killer for both
men and women.
Currently, 40% of Canadians have elevated cholesterol.
Both diet and lifestyle affect the risk of developing
cardiovascular disease.
Atherosclerosis is a disease in which lipids and fibrous
material are deposited in artery walls.
Copyright 2012, John Wiley & Sons Canada, Ltd.
Lipids and Cardiovascular Disease
Copyright 2012, John Wiley & Sons Canada, Ltd.
Lipids and Cardiovascular
Disease
Copyright 2012, John Wiley & Sons Canada, Ltd.
Lipids and Cardiovascular Disease
Copyright 2012, John Wiley & Sons Canada, Ltd.
Lipids and Cardiovascular
Disease
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Dietary factors that may help to reduce the
risk of heart disease include:
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Consuming omega-3 and omega-6 polyunsaturated
fats
Consuming monounsaturated fats
Consuming plant foods, including fruits and
vegetables, whole grains and legumes
Adequate intake of B vitamins
Moderate alcohol consumption
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Prevention Cardiovascular Disease
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Reducing Saturated Fat Intake
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Reducing Saturated Fat Intake (cont’d)
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Tools for Assessing Fat Intake
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Tools for Assessing Fat Intake
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Tools For Assessing Fat Intake (cont’d)
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Tools For Assessing Fat Intake (cont’d)
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Dietary Fat and Cancer
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Dietary Fat has been suggested to be both a
tumour promoter and a tumour initiator.
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How to Choose Fats Wisely
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How to Choose Fats Wisely (cont’d)
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The Health Check logo is a program started
by the Heart and Stroke Foundation of
Canada. It sets criteria for grocery and
restaurant menu items.
Criteria include: total fat, saturated fat, trans
fat, fibre, sodium, sugar, protein and certain
vitamins and minerals. Items that meet the
criteria may display the logo.
Copyright 2012, John Wiley & Sons Canada, Ltd.
How to Choose Fats Wisely (cont’d)
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Reduced-Fat Foods
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Reduced-fat foods either have fat removed,
have fat replaced or contain fats that cannot
be digested or absorbed.
Fat substitutes can be carbohydrate-, proteinor fat-based.
Fat substitutes are supposed to mimic the
taste and texture of fat.
Copyright 2012, John Wiley & Sons Canada, Ltd.
Copyright
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Copyright 2012, John Wiley & Sons Canada, Ltd.