Veggie Diet May Lower High Blood Pressure
Vegetarians tend to have lower blood pressure
than the general population, but it hasn't been clear whether their
diet or their lifestyle guards them against hypertension.
Now, a new review of previously published
studies claims that diet provides the protection.
"It's the diet itself, and it is
clearly the diet of choice for people who want to get their blood
pressure under control," said Dr. Neal D. Barnard, president and
founder of the Physicians Committee for Responsible Medicine and
co-author of the report, which appears in the January issue of Nutrition
Barnard, a nutritionist and author
of the book Breaking the Food Seduction: The Hidden Reasons Behind
Food Cravings and Seven Steps to End Them Naturally, concluded
that a person who suffers from hypertension and has yet to switch
to a vegetarian diet is "really trying to fight their condition
with one arm tied behind their back."
About 65 million American adults
have high blood pressure, according to the National Heart, Lung,
and Blood Institute. Hypertension is often called the "silent killer"
because it usually has no symptoms but leads to increased risk for
heart disease, congestive heart failure, stroke and kidney failure.
Barnard and committee nutritionist
Susan Berkow analyzed 80 scientific studies, including observational
studies of individuals on vegetarian diets compared with non-vegetarians
and randomized, controlled trials in which outcomes of people who
switch to a plant-based diet were compared with control subjects.
"The purpose of our review was to
bring together what is known about the effect of the diet, but also
what we know about the mechanism and try to explain why this occurs,"
Some of the best observational data,
according to the report, come from studies involving Seventh-Day
Adventists, who advocate an alcohol-free, tobacco-free, vegetarian
lifestyle. About 50 percent of Adventists follow a lacto-ovo-vegetarian
diet, which includes dairy products and eggs, the authors noted.
One study involving California Adventists
found that vegetarians have about half the prevalence of hypertension
compared to non-vegetarian Adventists. When hypertensives were defined
as those taking medication intended to reduce their blood pressure,
a nearly threefold difference in the prevalence of hypertension
was seen between the groups.
Overall, the randomized controlled
trials included in the review found that blood pressure is lowered
when animal products were replaced with vegetable products in both
people with normal blood pressure and those who are hypertensive.
To understand the blood-pressure-lowering
effects of a plant-based diet, the authors examined changes in body
weight and intake of specific food groups and nutrients.
Studies show that vegetarians tend
to be slimmer, on average, which may help explain their lower incidence
of hypertension. A vegetarian diet also is significantly lower in
saturated fat, reducing the viscosity, or thickness, of the blood.
Blood becomes "less like oil, more
like water," Barnard explained.
And because vegetarian diets are
generally high in fruits and vegetables, people who follow this
diet consume more potassium than those who eat a diet of meat and
vegetables. The analysis cites two reviews involving a total of
52 randomized clinical trials showing potassium supplementation
significantly lowered blood pressure in people with normal and elevated
There are those who disagree with
the finding, however.
Dr. Lawrence J. Appel, a nutrition
specialist at the Johns Hopkins Bloomberg School of Public Health,
said the paper fails to establish a clear cause-and-effect relationship
between consuming a plant-based diet and lowering one's blood pressure.
"It's a good review, but there are
still unanswered questions," he said.
He also noted that very few clinical
trials have been conducted, and that those that have been done are
small and not tightly controlled. Much of the data is observational.
So, he said, it remains unclear whether
a vegetarian diet alone is responsible for lowering blood pressure
or whether some aspect of a vegetarian regimen -- such as eating
lots of fruits and vegetables rich in potassium and fiber while
maintaining a desirable body weight -- could have the same effect.
And then there there is the fact
that not everyone who has high blood pressure eats poorly or is
overweight; genetic factors significantly influence a person's risk
Still, Barnard insists a vegetarian
diet is healthy for everyone, whether or not they have high blood
He offers this caveat for people
taking blood pressure medication: "Don't throw your medication in
the trash." High blood pressure is a serious medical condition requiring
immediate medical attention. Even if you switch to a vegetarian
diet to trim down, you won't lose the weight overnight, he said.
It could take more than a year for a person who is 60 pounds overweight
to drop that excess baggage.
Barnard hopes the review will prompt
more doctors to recommend a vegetarian diet. Many are reluctant
to do because they fear that patients won't stick with it, but there's
no reason to believe patients would be less likely to go vegetarian
than to comply with other diets, he said.
"They may not hit the mark 100 percent,
but they'd do much better if a doctor recommended it," he said.
Barnard's group, the physicians committee,
is a Washington, D.C.-based nonprofit that promotes good nutrition,
opposes unethical human experimentation and advocates alternatives
to animal research.
information on preventing high blood pressure
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