Researchers said for some people, eating a
vegetarian diet could be a good way to treat high blood pressure
Vegetarian diets exclude meat, but may include dairy products, eggs
and fish in some cases. They emphasize foods of plant origin,
particularly vegetables, grains, legumes and fruits.
High blood pressure contributes to a person's risk of heart disease,
stroke, kidney disorders and other health problems. For many people,
the only treatment has been medication, but that means costs and
possible side effects, lead author Yoko Yokoyama told Reuters Health
in an email.
"If a diet change can prevent blood pressure problems or can reduce
blood pressure, it would give hope to many people," Yokoyama said.
She is a researcher at the National Cerebral and Cardiovascular
Center in Osaka, Japan.
"However, in order to make healthful food choices, people need
guidance from scientific studies," she said. "Our analysis found
that vegetarian diets lower blood pressure very effectively, and the
evidence for this is now quite conclusive."
According to the American Heart Association, blood pressure readings
under 120 mm Hg systolic and 80 mm Hg diastolic (120/80) are
considered normal. High blood pressure starts at 140/90.
The new review, published in JAMA Internal Medicine, combined
results from 39 previous studies, including 32 observational studies
and seven controlled trials.
"Observational studies show what happens when people have chosen
their own diets and stuck with them, often for years," Yokoyama
said. "Controlled trials are different — a diet is given to people
who had not tried it before, and that will show the effect of
beginning a new way of eating."
Together the studies included close to 22,000 people.
The researchers found that in the observational studies, people who
had been eating a vegetarian diet had an average systolic blood
pressure that was about 7 mm Hg lower than among meat-eaters and a
diastolic blood pressure that was 5 mm Hg lower.
Participants in the clinical trials who were given vegetarian diets
to follow had, on average, a systolic blood pressure that was 5 mm
Hg lower and a diastolic blood pressure that was 2 mm Hg lower than
participants in control groups who were not on vegetarian diets.
"Unlike drugs, there is no cost to a diet adjustment of this type,
and all the 'side effects' of a plant-based diet are desirable:
weight loss, lower cholesterol, and better blood sugar control,
among others," Yokoyama said.
She said a plant-based diet is typically low in fat and high in
fiber, so it helps people lose weight, which, in turn, causes a
healthy drop in blood pressure.
"But there is more," Yokoyama said. "Plant-based foods are often low
in sodium and are rich in potassium, and potassium lowers blood
The same foods are also very low in saturated fat — the type of fat
in meat and cheese — and eating less saturated fat means blood can
circulate more easily, she explained.
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"I would encourage physicians to prescribe plant-based diets as a
matter of routine, and to rely on medications only when diet changes
do not do the job," Yokoyama said. "And I would encourage everyone
to try a plant-based diet, and especially to introduce plant-based
diets to their children — they could prevent many health problems."
Alice Lichtenstein, director of the Cardiovascular Nutrition
Laboratory at Tufts University in Boston, said the results of the
review are encouraging, but added that it didn't take sodium in the
diet and lifestyle factors into account.
"Individuals who adhere to vegetarian diets are likely to use
fewer processed foods, the major source of dietary sodium, and
adhere to healthy lifestyles behaviors such as maintaining a body
weight in the optimal range and engaging in regular physical
activity," Lichtenstein told Reuters Health in an email. She was not
involved in the new research.
"Until we understand the contribution of these factors we can't
attribute the effect observed solely to adhering to a vegetarian
diet," Lichtenstein explained.
"We certainly would not encourage substituting a slice of quiche for
a grilled chicken breast for dinner, due to the sodium, calories and
saturated fat," she said.
What's more, the findings do not mean that people taking blood
pressure medication should go off their drugs in favor of diet
changes without talking to a doctor.
Yokoyama said doctors who would like to prescribe diet changes need
"We have developed a free program, called the 21-Day Kickstart
program, which introduces a plant-based diet through daily emails
that provide menus, recipes, cooking videos, and a discussion board
for questions. It is available at no charge in English, Spanish,
Mandarin, and Japanese, along with a special English-language
program for India," Yokoyama said.
The program is affiliated with the Physicians Committee for
Responsible Medicine, an organization that promotes plant-based
diets. It is available online here: http://bit.ly/1fnATB9.
JAMA Internal Medicine, online Feb. 24, 2014.
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