Flaxseed and Cardiovascular Disease

Flaxseed
and
Disease
TM
healthyflax.org
Flaxseed and Cardiovascular Disease
By Jennifer Adolphe, PhD, RD and Kelley Fitzpatrick, MSc
Flaxseed is rich in omega-3 fatty acids, soluble fibre, and lignans that promote
cardiovascular health.
Regular consumption of flaxseed as part of a healthy diet reduces serum total
and LDL cholesterol.
Health Canada has permitted the use of blood cholesterol lowering claim for
ground flaxseed.
Cardiovascular disease (CVD) includes all diseases of the heart and vasculature and has been the
leading cause of mortality during the past decade.1 An estimated 9 in 10 Canadians have at least
one CVD risk factor, with over 40 percent of individuals aged 20 to 79 having elevated
levels of total cholesterol.2 In the United States, CVD accounts for approximately
one out of every three deaths, with more than 2,150
Americans dying each day.3 Many of the factors that contribute to the
development of atherosclerotic CVD can be altered by lifestyle
modification, including dietary choices. In fact, nutritional factors have
been estimated to be responsible for as much as 40% of all CVD.4
Flaxseed contains three components associated with improved
cardiovascular health: the omega-3 polyunsaturated fatty acid
alpha-linolenic acid (ALA, 20% of dry weight); the plant lignan
secoisolariciresinol diglucoside (SDG, 1% of dry weight); and soluble fibre (6%
of dry weight).5 These constituents can positively affect blood lipid levels, blood
pressure, endothelial function, and inflammation to mitigate CVD risk.
Alpha-Linolenic Acid: A Heart-Healthy Essential Omega-3 Fatty Acid
Omega-3 ALA and omega-6 linoleic acid (LA) are the two essential fatty acids required in the
human diet since they cannot be endogenously synthesized. Flaxseed is the richest plant source
of ALA. A meta-analysis of 27 prospective and retrospective studies reported that each 1 g/d
increment of ALA intake was associated with a 10% lower risk of death from heart disease.6 Higher
intakes have also been associated with lower risk of myocardial infarction (MI). A large study in
3,638 men and women reported a strong negative correlation between ALA status, measured in
adipose tissue, and corresponding intakes of 1.8 g ALA/day with nonfatal myocardial infarction
(MI)7. And men who consumed more than 1 g ALA/day had a 35 to 50 per cent lower risk of stroke
after 8 to 13 years of follow up in a study of 20,069 people8. Individuals with low ALA intakes
(less than 1 g/day) may experience the greatest cardiovascular benefits from increasing intakes.7
Greek Oat Bread recipe at HealthyFlax.org
Omega-3
Omega-3 fatty
fatty acids
acids are
are typically
typically low
low in
in the
the diet
diet of
of North
North Americans.
Americans. The
The minimum
minimum recomrecommended
mended Daily
Daily Value
Value for
for ALA
ALA Omega-3
Omega-3 is
is 1,600-mg
1,600-mg per
per day.
day.99 As
As well,
well, the
the American
American Heart
Heart AssociaAssociation
tion recommends
recommends eating
eating sources
sources of
of ALA,
ALA, including
including flaxseed
flaxseed and
and its
its oil,
oil, due
due to
to large
large epidemioepidemiologic
logic studies
studies suggesting
suggesting that
that people
people at
at risk
risk for
for coronary
coronary heart
heart disease
disease benefit
benefit from
from consuming
consuming
The Academy
Academy of
of Nutrition
Nutrition and
and Dietetics
Dietetics
both
both plant
plant and
and marine
marine sources
sources of
of omega-3
omega-3 fatty
fatty acids.
acids.1010 The
recommends
recommends that
that ALA
ALA provide
provide 0.6
0.6 to
to 1.2
1.2 percent
percent of
of energy
energy intake.
intake.1111
The
The ratio
ratio of
of omega-6
omega-6 to
to omega-3
omega-3 fatty
fatty acids
acids may
may also
also be
be important
important for
for optimal
optimal health.
health. The
The
Institute
Institute of
of Medicine
Medicine recommends
recommends an
an omega-6
omega-6 to
to omega-3
omega-3 ratio
ratio of
of 5:1
5:1 to
to 10:1.9
10:1.9 However,
However, this
this
Flax contains
contains more
more than
than three
three times
times as
as
ratio
ratio may
may be
be as
as high
high as
as 17:1
17:1 in
in Western-type
Western-type diets.
diets.1212 Flax
much
much omega-3
omega-3 as
as omega-6
omega-6 fatty
fatty acids,
acids, giving
giving aa ratio
ratio of
of only
only 0.3:1.
0.3:1. ALA
ALA is
is the
the dietary
dietary precursor
precursor for
for
the
the longer
longer chain
chain omega-3
omega-3 fatty
fatty acids
acids eicosapentaenoic
eicosapentaenoic acid
acid (EPA)
(EPA) and
and docosahexaenoic
docosahexaenoic acid
acid
The rate
rate of
of ALA
ALA conversion
conversion varies
varies between
between individuals
individuals and
and
(DHA),
(DHA), which
which are
are found
found in
in seafood.
seafood.1313 The
can
can be
be impaired
impaired by
by aa diet
diet high
high in
in omega-6
omega-6 LA.
LA.1313 EPA
EPA is
is further
further metabolized
metabolized to
to hormone-like
hormone-like
substances
substances called
called eicosanoids.
eicosanoids. The
The eicosanoids
eicosanoids produced
produced from
from EPA
EPA possess
possess anti-inflammatory
anti-inflammatory
properties
properties that
that help
help protect
protect against
against CVD,
CVD, whereas
whereas eicosanoids
eicosanoids produced
produced from
from metabolites
metabolites of
of LA
LA
have
have pro-inflammatory
pro-inflammatory characteristics.
characteristics. Low
Low ALA
ALA intake
intake supports
supports the
the production
production of
of omega-6
omega-6
eicosanoids
eicosanoids at
at the
the expense
expense of
of omega-3
omega-3 eicosanoids,
eicosanoids, which
which has
has negative
negative implications
implications for
for
cardiovascular
cardiovascular health.
health.
healthyflax.org
TM
YELLOW FLAXSEED
Serum
Serum levels
levels of
of inflammatory
inflammatory proteins
proteins were
were reduced
reduced after
after dietary
dietary supplementation
supplementation with
with ALA
ALA
from
from walnuts,
walnuts, walnut
walnut oil,
oil, and
and flaxseed
flaxseed oil.
oil.1414 Using
Using cultured
cultured peripheral
peripheral blood
blood mononuclear
mononuclear cells
cells
from
from these
these same
same subjects,
subjects, the
the diet
diet high
high in
in ALA
ALA inhibited
inhibited the
the production
production of
of pro-inflammatory
pro-inflammatory
agents
agents including
including IL-6,
IL-6, IL-1β,
IL-1β, and
and TNF-α
TNF-α production.
production.1515
On
On the
the basis
basis of
of aa review
review of
of numerous
numerous studies
studies which
which focused
focused on
on ALA,
ALA, Fleming
Fleming and
and Kris-Etherton
Kris-Etherton
conclude
conclude that
that there
there is
is evidence
evidence demonstrating
demonstrating aa beneficial
beneficial role
role of
of ALA
ALA for
for the
the primary
primary and
and
secondary
secondary prevention
prevention of
of CVD.
CVD. Further,
Further, itit was
was recommended
recommended that
that ALA
ALA intake
intake be
be increased
increased to
to 22 to
to 33
g/day
g/day to
to reduce
reduce risk
risk of
of CVD.
CVD.1616
As
As aa plant
plant source
source of
of omega-3
omega-3 fatty
fatty acids,
acids, flaxseed
flaxseed is
is aa renewable
renewable and
and sustainable
sustainable source
source of
of this
this
essential
essential fatty
fatty acid.
acid.1717
BROWN FLAXSEED
Oat and Apple Pancake recipe at HealthyFlax.org
YELLOW GROUND FLAXSEED
Flaxseed
Flaxseed is
is aa Rich
Rich Source
Source of
of Soluble
Soluble Fibre
Fibre and
and Lignans
Lignans
Flaxseed
Flaxseed contains
contains mucilage
mucilage gums,
gums, aa type
type of
of soluble
soluble dietary
dietary fibre.
fibre. Increased
Increased consumption
consumption of
of
Soluble fibre
fibre binds
binds bile
bile
soluble
soluble fibre
fibre can
can reduce
reduce the
the risk
risk of
of CVD
CVD by
by reducing
reducing LDL
LDL cholesterol.
cholesterol.1818 Soluble
acids
acids in
in the
the intestine
intestine thereby
thereby increasing
increasing fecal
fecal excretion.
excretion. Since
Since cholesterol
cholesterol is
is aa precursor
precursor for
for bile
bile
Soluble fibre
fibre may
may also
also
acids,
acids, increased
increased excretion
excretion causes
causes decreased
decreased circulating
circulating cholesterol
cholesterol levels.
levels.1818 Soluble
help
help to
to lower
lower serum
serum cholesterol
cholesterol levels
levels as
as aa result
result of
of fermentation
fermentation in
in the
the large
large intestine
intestine and
and
In addition
addition
production
production of
of short-chain
short-chain fatty
fatty acids
acids that
that lower
lower pH
pH and
and inhibit
inhibit cholesterol
cholesterol synthesis.
synthesis.1818 In
to
to improving
improving serum
serum lipid
lipid levels,
levels, dietary
dietary fibre
fibre lowers
lowers blood
blood pressure
pressure and
and reduces
reduces inflammation
inflammation to
to
The Institute
Institute of
of Medicine
Medicine has
has set
set the
the Adequate
Adequate Intake
Intake for
for total
total dietary
dietary fibre
fibre at
at
help
help prevent
prevent CVD.
CVD.1919 The
14
14 gg per
per 1000
1000 kcal,
kcal, or
or about
about 25
25 g/day
g/day for
for women
women and
and 38
38 g/day
g/day for
for men.
men.1919
BROWN GROUND FLAXSEED
Lignans
Lignans are
are phytoestrogens
phytoestrogens –– compounds
compounds in
in plants
plants that
that possess
possess estrogen-like
estrogen-like properties.
properties.
Flaxseed
Flaxseed has
has up
up to
to 800
800 times
times more
more active
active lignans
lignans compared
compared to
to vegetables,
vegetables, fruits,
fruits, legumes,
legumes, cereals,
cereals,
or
or seeds.
seeds. SDG
SDG is
is the
the major
major lignan
lignan found
found in
in flaxseed.
flaxseed. Once
Once ingested,
ingested, SDG
SDG is
is converted
converted to
to active
active
mammalian
mammalian lignans,
lignans, enterodiol
enterodiol and
and enterolactone.
enterolactone.
Oxidative
Oxidative stress
stress and
and inflammation
inflammation contribute
contribute to
to an
an atherogenic
atherogenic environment
environment that
that promotes
promotes the
the
development
development of
of CVD.
CVD. Flaxseed
Flaxseed SDG
SDG and
and its
its metabolites
metabolites possess
possess potent
potent antioxidant
antioxidant properties,
properties,
In addition,
addition, flax
flax lignans
lignans have
have been
been
thereby
thereby reducing
reducing oxidative
oxidative stress
stress and
and protecting
protecting against
against CVD.
CVD.55 In
shown
shown to
to reduce
reduce the
the progression
progression of
of atherosclerosis
atherosclerosis and
and improve
improve blood
blood pressure.
pressure.55
Recent
Recent science
science is
is supporting
supporting even
even further
further positive
positive effects
effects of
of flaxseed.
flaxseed. A
A double
double blind
blind randomized
randomized
controlled
controlled trial
trial that
that fed
fed participants
participants 30
30 g/day
g/day of
of ground
ground flaxseed
flaxseed for
for six
six months
months found
found increased
increased
In the
the group
group that
that received
received ground
ground flaxseed,
flaxseed, systolic
systolic
plasma
plasma levels
levels of
of ALA
ALA and
and enterolignans.
enterolignans.44 In
blood
blood pressure
pressure decreased
decreased by
by 10
10 mm
mm Hg
Hg and
and diastolic
diastolic blood
blood pressure
pressure decreased
decreased by
by 77 mm
mm Hg
Hg
This is
is one
one of
of the
the most
most potent
potent antihypertensive
antihypertensive effects
effects observed
observed as
as the
the
compared
compared to
to placebo.
placebo.44 This
result
result of
of aa dietary
dietary intervention
intervention and
and is
is even
even more
more significant
significant than
than some
some common
common drugs
drugs used
used to
to
treat
treat the
the disease.
disease.44
A Health Claim for Flaxseed
References
References
In 2014, Health Canada approved a health claim linking
ground whole flaxseed to blood cholesterol lowering, a
major risk factor for CVD.20 The claim – only one of eleven
approved in Canada - was based on seven clinical
research trials of normal and hypercholesterolemic
males and females aged 8 to 75 years who consumed 30
to 50 g/day of ground flaxseed. The primary endpoints in
these studies were total cholesterol and low density
lipoprotein (LDL) cholesterol, recognized risk factors for
CVD. The pooled results from these studies found that
compared to baseline, total cholesterol levels decreased
by 0.21 mmol/L (- 0.56 to - 9.01 percent) and LDL
decreased by 0.22 mmol/L (- 3.42 to -14.94 percent).20
A reduction of 1 percent in total cholesterol levels is
related to a 2 percent reduction in risk of CVD. Therefore,
according to these studies, flaxseed intake may decrease
the risk of CVD between 1 and 18 percent.
World
Health
Organization.2013.
2013.The top
1. 1.World
Health
Organization.
top tof
10 causes
10The
causes
death. tof death.
http://www.who.int/mediacentre/fact
http://www.who.int/mediacentre/factsheets/fs310/en/ Accessed January 18
sheets/fs310/en/
2014. January 18 2014.
Accessed
The “daily amount” referred
to in the claim is 40 g
(5 tablespoons) of ground
whole flaxseed to be consumed over three eating
occasions in the day.
HealthyFlax.org is the source of An example of the permitted claim for ground flaxseed
is: “16 g (2 tablespoons) of ground flaxseed supplies 40%
of the daily amount shown to help lower cholesterol”.
In addition to this primary statement, the following
additional statements may be used:
information on the health
• Ground (whole) flaxseed helps reduce/lower
benefits and uses of whole
flaxseed, ground flaxseed and flaxseed oil. Our website includes
recipes, nutritional evidence,
facts and news about flaxseed in
all its forms. HealthyFlax.org is
supported by Canada's flax
growers, processors, food
manufacturers and governments. For more information,
email us at info@healthyflax.org
TM
healthyflax.org
twitter.com/HealthyFlax
cholesterol
• High cholesterol is a risk factor for heart disease
• Ground (whole) flaxseed helps reduce/lower
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Flaxseed has been consumed for centuries due to its
desirable flavor and nutritional properties. In recent
years, as people have become more concerned about
health, demand for flaxseed in food and beverages has
risen dramatically. Scientific research and now regulatory
approval supports the heart health benefits of flaxseed,
particularly due to ALA, fibre and lignan contents.
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andClaim
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Lowering Cholesterol Lowering http://www.hchttp://www.hc-sc.gc.ca/fn-an/alt_forsc.gc.ca/fn-an/alt_formats/pdf/label-mats/pdf/label-etiquet/claims-reclam/
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January 2015