Eating a bit of flaxseed each day might
help lower high blood pressure, a new study suggests.
Researchers said it's too early to swap out
blood pressure medication for the fibre-filled seeds just yet. But if future
studies confirm the new results, flax might be a cheap way to treat high blood
pressure, they added.
Flaxseed is well known as a plant source of
omega-3 fatty acids, fibre and lignans, a type of anti-oxidants.
But so far, its effect on high blood
pressure, or hypertension, has been better studied among animals than
humans. "This is the first demonstration of the cardiovascular effects of
dietary flaxseed in a hypertensive population," Grant Pierce told Reuters
Health in an email.
Pierce is the senior author on the study and
executive director of research at St Boniface Hospital in Winnipeg, Manitoba, Canada.
One in three American adults has high blood pressure, considered 140/90 millimetres
of mercury (mm Hg) and over, according to the National Institutes of Health.
Increased heart disease risk
Having high blood pressure increases a
person's risk of heart disease and stroke. The condition costs the US billions
of dollars each year, Pierce said. "It is the number one reason for a person
to visit a physician in the US today," he said.
"Understanding how to reduce blood
pressure has become, therefore, a critical challenge. "His team's results
were published in the journal Hypertension. The trial included 110 people who
had been diagnosed with peripheral artery disease, in which plaque builds up in
arteries in the leg.
Patients with the condition often have high
blood pressure. The participants were randomly assigned to either a flaxseed or
comparison group. People in the flaxseed group ate a variety of foods like
bagels, muffins and pasta that contained 30 grams – about one ounce – of milled
flaxseed every day for six months.
Those in the comparison group were given
foods that tasted similar, but didn't contain any flaxseed. The researchers had
participants increase their dose of flaxseed gradually so they could become
accustomed to the fibre load.
Still, one in five participants dropped out of
each group during the trial. Some of that could have been due to stomach pain
from the extra fibre, Pierce said.
People who had an initial systolic blood
pressure – the top number in a blood pressure reading – of at least 140 mm Hg
saw that figure drop by 15 mm Hg, on average, after six months of taking flaxseed.
Their diastolic blood pressure – the bottom number – also fell by 7 mm Hg.
Blood pressure did not change among people with hypertension in the comparison
group. "These decreases in (blood pressure) are amongst the most potent
dietary interventions observed and comparable to current medications,"
There was no flaxseed-related benefit for
people with normal blood pressure, however. Flaxseed costs about 25c to 50c per
The new study was partially funded by the
Flax Council of Canada. It wasn't originally designed to study blood pressure,
which means the results have to be interpreted with more caution.
"The study results are indeed surprising – it is actually hard to imagine such huge reductions in blood pressure with
flax seed mixed in food stuffs," Dr William B White told Reuters Health
in an email.
White, from the University of Connecticut
School of Medicine in Farmington, is also the president of the American Society
of Hypertension. He was not involved in the new study. He also expressed some
concern that measuring blood pressure changes was not the initial reason for
doing the study.
he said the way blood pressure was measured – during a single office visit –
isn't as accurate as checking it at multiple points throughout the
day. "The results are preliminary – there is not enough information to
justify people taking flax seed for the control of hypertension.
larger, more controlled trial with out-of-office blood pressure would be
needed," White said. According to Pierce, a new study is underway.
Picture: Flaxseeds from Shutterstock