Flaxseed
and
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Flaxseed and Hypertension
By Stephanie Caligiuri, MSc and Kelley Fitzpatrick, MSc
Flaxseed is rich in omega-3 fatty acids, lignans, fibre, and arginine and shows
powerful blood pressure lowering effects.
The addition of 30 g/d of dietary flaxseed to standard of care improved the
percentage of patients who were able to control their blood pressure from
34% to 53% following one year of intervention.1
The therapeutic benefits of flaxseed may be greater than commonly
prescribed antihypertensive medications.
Hypertension
Hypertension, known as the “silent killer”, represents a global health crisis contributing to 9.4
million deaths per year and affecting more than 40% of adults aged 25 years and older.2 If left
uncontrolled, hypertension can lead to heart attacks, strokes, kidney failure, blindness, dementia, and peripheral arterial disease (PAD), which is a serious plaque build-up in the arteries of
arms and legs.2
When measuring blood pressure, the top number, or systolic pressure, refers to the pressure
inside the arteries when the heart contracts and pumps blood through the body. The bottom
number, or diastolic pressure, refers to the pressure inside the arteries when the heart is at rest
and is filling with blood. Both are recorded in millimeters of mercury (mmHg) with normal
being defined as less than 120/80mm Hg.3
Pre-Hypertension
120/80 – 139/89 mmHg
Stage 1 Hypertension
140/90 – 159/99 mmHg
Stage 2 Hypertension
160/100 mmHg or higher
Lifestyle factors that may lead to high blood pressure include heavy alcohol consumption, high
salt intake, and obesity. Another potential cause is inflammation which can negatively affect
the inside lining of blood vessels (the endothelium)4. Chronic inflammation can cause “endothelial dysfunction”, an imbalance between vasodilating and vasoconstricting substances
produced by, or acting on, the endothelium. Enhanced constriction of the vessels can result in
hypertension and further the development of atherosclerosis.4
Flaxseed
Flaxseed lowers
lowers blood
blood pressure
pressure
Saskatoon Oat & Seed Bread recipe at HealthyFlax.org
Flaxseed
Flaxseed (Linum
(Linum usitatissimum)
usitatissimum) is
is aa rich
rich source
source of
of protein,
protein, fat,
fat, and
and dietary
dietary fibre.
fibre. Canadian
Canadian
flaxseed
flaxseed contains
contains on
on average
average 41%
41% fat,
fat, 20%
20% protein,
protein, and
and 28%
28% total
total dietary
dietary fibre.
fibre. This
This modest
modest
seed
seed has
has health-promoting
health-promoting qualities
qualities due
due to
to its
its content
content of
of four
four health-promoting
health-promoting components:
components:
the
the omega-3
omega-3 polyunsaturated
polyunsaturated fatty
fatty acid
acid alpha-linolenic
alpha-linolenic acid
acid (ALA),
(ALA), accounting
accounting for
for 20%
20% of
of
flaxseed
flaxseed dry
dry weight,
weight, the
the plant
plant lignan
lignan secoisolariciresinol
secoisolariciresinol diglucoside
diglucoside (SDG),
(SDG), representing
representing 1%
1%
of
of dry
dry weight,
weight, soluble
soluble fibre
fibre representing
representing 6%
6% of
of dry
dry weight,
weight, and
and protein.
protein.55
Flaxseed
Flaxseed has
has aa unique
unique mix
mix of
of fatty
fatty acids
acids with
with low
low saturated
saturated fat
fat content
content (only
(only 7%
7% of
of total
total fatty
fatty
acids)
acids) as
as well
well as
as the
the essential
essential polyunsaturated
polyunsaturated fatty
fatty acids
acids (PUFA),
(PUFA), omega-3
omega-3 ALA
ALA and
and omega-6
omega-6
linoleic
linoleic acid
acid (LA).
(LA). Approximately
Approximately 57%
57% of
of the
the fatty
fatty acids
acids are
are ALA,
ALA, making
making flaxseed
flaxseed the
the richest
richest
plant
plant source
source of
of this
this important
important omega-3.
omega-3.55
Research
Research has
has been
been performed
performed on
on the
the individual
individual components
components of
of flaxseed
flaxseed to
to isolate
isolate their
their
therapeutic
therapeutic effects.
effects. In
In adults
adults with
with high
high blood
blood cholesterol,
cholesterol, adding
adding one
one tablespoon
tablespoon (15
(15 mL)
mL) of
of
flaxseed
flaxseed oil
oil (8
(8 gg of
of ALA)
ALA) every
every day
day for
for 12
12 weeks
weeks lowered
lowered systolic/diastolic
systolic/diastolic blood
blood pressure
pressure by
by
In obese
obese adults,
adults, consumption
consumption of
of 20
20 g/d
g/d of
of flaxseed
flaxseed oil
oil for
for 44 weeks
weeks improved
improved
10/8
10/8 mmHg.
mmHg.66 In
The intake
intake of
of 543
543 mg/day
mg/day of
of the
the flax
flax lignan,
lignan, SDG,
SDG, for
for 24
24
mean
mean arterial
arterial pressure
pressure by
by 13
13 mmHg.
mmHg.77 The
weeks
weeks significantly
significantly lowered
lowered diastolic
diastolic blood
blood pressure
pressure by
by 44 mm
mm Hg
Hg in
in older
older males
males and
and by
by 6.7
6.7
mmHg
mmHg in
in those
those with
with metabolic
metabolic syndrome,
syndrome, aa group
group of
of risk
risk factors
factors that
that raises
raises the
the risk
risk for
for heart
heart
disease
disease and
and other
other health
health problems.
problems.88
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YELLOW FLAXSEED
YELLOW GROUND FLAXSEED
Although
Although the
the individual
individual flaxseed
flaxseed nutrients
nutrients have
have demonstrated
demonstrated important
important health
health effects,
effects, the
the
most
most powerful
powerful blood
blood pressure
pressure lowering
lowering outcomes
outcomes have
have been
been shown
shown in
in humans
humans with
with the
the
consumption
consumption of
of whole
whole ground
ground flaxseed
flaxseed containing
containing ALA,
ALA, lignans,
lignans, fibre
fibre and
and protein.
protein. In
In groundgroundbreaking
breaking research,
research, Canadian
Canadian scientists
scientists discovered
discovered that
that 30
30 g/d
g/d of
of ground
ground flaxseed
flaxseed reduced
reduced
blood
blood pressure
pressure in
in patients
patients with
with PAD
PAD and
and uncontrolled
uncontrolled hypertension
hypertension by
by 15
15 mmHg
mmHg (systolic)
(systolic) and
and
This is
is larger
larger than
than the
the average
average reduction
reduction
77 mmHg
mmHg (diastolic)
(diastolic) after
after 66 months
months (the
(the FlaxPAD
FlaxPAD trial).
trial).99 This
achieved
achieved with
with standard
standard doses
doses of
of blood
blood pressure
pressure lowering
lowering medications
medications (such
(such as
as diuretics,
diuretics,
angiotensin
angiotensin converting
converting enzyme
enzyme inhibitors,
inhibitors, angiotensin
angiotensin receptor
receptor blockers,
blockers, calcium
calcium channel
channel
A randomized,
randomized, controlled,
controlled, double-blinded
double-blinded clinical
clinical trial
trial currently
currently
blockers,
blockers, and
and beta-blockers).
beta-blockers).1010 A
underway
underway will
will investigate
investigate ifif ground
ground flaxseed
flaxseed can
can lower
lower blood
blood pressure
pressure and
and prevent
prevent the
the need
need for
for
medication
medication in
in people
people newly
newly diagnosed
diagnosed with
with Stage
Stage 11 Hypertension.
Hypertension.1111
As
As aa secondary
secondary observation
observation to
to the
the FlaxPAD
FlaxPAD trial,
trial, the
the addition
addition of
of 30
30 g/d
g/d of
of dietary
dietary flaxseed
flaxseed to
to
standard
standard of
of care
care (ongoing
(ongoing lifestyle
lifestyle and
and diet
diet information
information plus
plus medication)
medication) improved
improved the
the percentpercentage
age of
of patients
patients who
who were
were able
able to
to control
control their
their blood
blood pressure
pressure from
from 34%
34% to
to 53%
53% following
following one
one
In contrast,
contrast, those
those patients
patients under
under the
the same
same standard
standard of
of care,
care, but
but without
without
year
year of
of intervention.
intervention.1212 In
dietary
dietary flaxseed,
flaxseed, showed
showed aa worsening
worsening in
in blood
blood pressure
pressure control
control from
from 44%
44% to
to 35%.
35%.
Caribbean Crunch Muffin recipe at HealthyFlax.org
In
In adults
adults with
with metabolic
metabolic syndrome,
syndrome, 30
30 g/d
g/d of
of whole
whole ground
ground flaxseed
flaxseed combined
combined with
with lifestyle
lifestyle
The consumption
consumption of
of 40
40 g/d
g/d
counseling
counseling lowered
lowered blood
blood pressure
pressure by
by 8.8/5.0
8.8/5.0 mmHg
mmHg in
in 12
12 weeks.
weeks.1313 The
of
of whole
whole ground
ground flaxseed
flaxseed reduced
reduced blood
blood pressure
pressure by
by 5.0/4.1
5.0/4.1 mmHg
mmHg in
in healthy
healthy postpostmenopausal
menopausal women
women after
after one
one year
year compared
compared to
to baseline.
baseline.1414
BROWN FLAXSEED
BROWN GROUND FLAXSEED
Mechanism
Mechanism of
of Action
Action of
of Flaxseed
Flaxseed
Flaxseed
Flaxseed appears
appears to
to reduce
reduce blood
blood pressure
pressure through
through its
its ability
ability to
to lower
lower plasma
plasma oxylipins
oxylipins which
which
are
are highly
highly bioactive
bioactive molecules
molecules produced
produced in
in the
the body
body from
from PUFA.
PUFA. Some
Some oxylipins
oxylipins can
can constrict
constrict
and
and others
others can
can dilate
dilate blood
blood vessels
vessels thereby
thereby affecting
affecting blood
blood pressure.
pressure. Flaxseed
Flaxseed has
has been
been shown
shown
to
to reduce
reduce vasoconstrictive
vasoconstrictive oxylipins
oxylipins by
by inhibiting
inhibiting soluble
soluble epoxide
epoxide hydrolase,
hydrolase, the
the enzyme
enzyme that
that
Clinical trials
trials are
are underway
underway to
to investigate
investigate the
the safety
safety and
and efficacy
efficacy of
of drugs
drugs that
that
produces
produces them.
them.1212 Clinical
inhibit
inhibit soluble
soluble epoxide
epoxide hydrolase
hydrolase in
in humans.
humans. While
While these
these drugs
drugs may
may take
take years
years to
to develop,
develop,
flaxseed
flaxseed is
is currently
currently readily
readily available
available and
and offers
offers aa natural
natural source
source of
of hypertension
hypertension therapy.
therapy.
Flaxseed
Flaxseed ALA
ALA and
and lignans
lignans may
may contribute
contribute to
to blood
blood pressure
pressure reduction
reduction through
through
4,11
Flaxseed
Flaxseed is
is also
also aa
anti-inflammatory
anti-inflammatory actions
actions that
that improve
improve the
the health
health of
of the
the endothelium.
endothelium.4,11
15
15
In 30
30 gg of
of ground
ground flaxseed
flaxseed
source
source of
of the
the amino
amino acid
acid arginine
arginine comprising
comprising 11.3%
11.3% of
of its
its protein.
protein. In
there
there is
is approximately
approximately 680
680 mg
mg of
of arginine.
arginine. In
In the
the body,
body, arginine
arginine is
is converted
converted to
to nitric
nitric oxide
oxide
which
which has
has the
the ability
ability to
to lower
lower blood
blood pressure
pressure through
through blood
blood vessel
vessel dilation.
dilation.1616
Scientific
Scientific research
research supports
supports the
the potent
potent blood
blood pressure
pressure lowering
lowering properties
properties of
of flaxseed.
flaxseed. The
The
ALA,
ALA, lignans,
lignans, fibre,
fibre, and
and protein
protein content
content of
of flaxseed
flaxseed together
together may
may knockout
knockout this
this silent
silent killer.
killer.
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.17 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).17 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.
1.1. Caligiuri
Curr
Hypertens
Rep.
CaligiuriSP
SPetetal.al.
Curr
Hypertens
2014;
16(12):499.
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16(12):499.
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.
benefits and uses of whole
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:
flaxseed, ground flaxseed and •
HealthyFlax.org is the source of information on the health
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 [email protected]
Ground (whole) flaxseed helps reduce/lower
cholesterol
•
High cholesterol is a risk factor for heart disease
•
Ground (whole) flaxseed helps reduce/lower
cholesterol, (which is) a risk factor for heart disease
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.
2.2. World
A global
brief
WorldHealth
HealthOrganization.
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Hypertension:
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flaxseed-graines-de-lin-eng.pdf
Accessed May 11 2014.
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