Beetroot
beneficial for athletes and heart failure patients, research finds
Football
teams are claiming it improves their athletic performance, and according to new
research from Kansas State University, it also benefits heart failure patients.
The special ingredient: beetroot.
Recently,
the Auburn University football team revealed its pregame ritual of taking
beetroot concentrate, or beet juice, before each game. The juice may have
contributed to the team's recent winning season — and one exercise physiologist
who has been studying the supplement for several years says that may be the
case.
"Our
research, published in the journal Physiology in 2013, has shown that
the nitrate found in beetroot concentrate increases blood flow to skeletal muscles
during exercise," said David Poole, professor of exercise kinesiology and
anatomy and physiology at Kansas State University. The journal Physiology
is widely regarded as the world's premiere physiology journal.
The
researchers' latest study, "Microvascular oxygen pressures in muscles
comprised of different fiber types: Impact of dietary nitrate
supplementation," was published in the Journal of Nitric Oxide, Biology
and Chemistry. This work provides the basis for how beetroot juice may
benefit football players by preferentially increasing blood flow to fast-twitch
muscle fibers — the ones used for explosive running. This work was performed by
Poole; Scott Ferguson, doctoral student in anatomy and physiology; and Timothy
Musch, professor of exercise kinesiology and anatomy and physiology, all at
Kansas State University.
In
addition to improving athletic performance, the research also found that
beetroot juice can improve the quality of life for heart failure patients.
"Remember,
for every one football player in the United States, there are many thousands of
heart failure patients that would benefit from this therapy," Poole said.
"It's a big deal because even if you can only increase oxygen delivery by
10 percent, that can be the difference between a patient being wheelchair-bound
versus getting up and walking around and interacting with his or her
family."
The
benefits of beetroot come from the nitrate found within it. The amount of
nitrate in one 70-milliliter bottle of beetroot juice is about the same amount
found in 100 grams of spinach.
"When
consumed, nitrate is reduced in the mouth by bacteria into nitrite,"
Ferguson said. "The nitrite is swallowed again and then reduced to nitric
oxide, which is a potent vasodilator. The nitric oxide dilates the blood
vessels, similar to turning on a water faucet, and allows blood to go where it
needs to go."
The
beetroot juice consumption resulted in a 38 percent higher blood flow to the
skeletal muscles during exercise and was preferential to the less-oxygenated,
fast-twitch muscles.
"Heart
failure is a disease where oxygen delivery to particular tissues, especially
working skeletal muscles, is impaired, decreasing the capacity to move the arms
or legs and be physically active," Poole said. "The best therapy for
these patients is getting up and moving around. However, that is often
difficult. Increasing the oxygen delivery to these muscles through beetroot can
provide a therapeutic avenue to improve the quality of life for these
patients."
Beets could lower risk of heart disease
New research from the University of
Reading has shown that eating four slices of bread containing beetroot lowers
blood pressure and improves the function of blood vessels, significantly
improving heart health.
The researchers provided 24
participants with four slices (200g) of bread containing 100g of beetroot, or
control bread with no beetroot enrichment once on two separate occasions. They
found the diastolic¹ blood pressure of those who consumed ‘beetroot bread' was
lowered by up to 7 mmHg when compared to the control group approximately 3
hours after consumption.
Evidence suggests that a reduction
in diastolic blood pressure of 5-6 mmHg over a five year period could reduce
the chances of a stroke by 38% and coronary heart disease by 23% less. In
addition, prolonged high blood pressure is an important risk factor for the
development of heart disease, which is the single biggest killer in the UK,
causing nearly 179, 000 deaths per year.
The component of beetroot bread
thought to be responsible for the beneficial effects on blood vessel function
and blood pressure is dietary nitrate. Dietary nitrate is a natural component
of beetroot and a number of other vegetables such as spinach, lettuce and
rocket.
When dietary nitrate is eaten it
produces nitric oxide in the blood vessel wall which causes relaxation of the
vessel and increased blood flow. This ultimately results in lowering of blood
pressure and an improvement in blood vessel function.
Julie Lovegrove, Professor of Human
Nutrition, Head of the Hugh Sinclair Unit of Human Nutrition and the Deputy
Director of the Institute for Cardiovascular and Metabolic Research (ICMR) at
the University of Reading, who led the study said: "These exciting and
novel findings show for the first time that bread containing beetroot improves
blood vessel function. This is an important addition to the increasing body of
evidence that suggests beneficial effects of dietary nitrate rich foods on the
heart.
"This research also supports
the findings of our previous study which was carried out last year and showed
that beetroot in the form of juice or bread lowers blood pressure.
Collectively, these studies suggest a potential role for foods rich in dietary
nitrate in the management of high blood pressure."
The study, published in the Journal of Nutrition, was undertaken by
Dr Ditte Hobbs in the University of Reading's Hugh Sinclair Human Nutrition
Group, which has an international reputation for its research into the
relationship between diet and the risk of chronic disease such as
cardiovascular disease, diabetes, neurodegenerative disease and cancer.
Drinking Cup of Beetroot Juice Daily May Help Lower Blood
Pressure
A cup of beetroot juice a day may
help reduce your blood pressure, according to a small study in the American
Heart Association journal Hypertension.
People with high blood pressure who
drank about 8 ounces of beetroot juice experienced a decrease in blood pressure
of about 10 mm Hg. But the preliminary findings don't yet suggest that supplementing
your diet with beetroot juice benefits your health, researchers said.
"Our hope is that increasing
one's intake of vegetables with a high dietary nitrate content, such as green
leafy vegetables or beetroot, might be a lifestyle approach that one could
easily employ to improve cardiovascular health," said Amrita Ahluwalia,
Ph.D., lead author of the study and a professor of vascular pharmacology at The
Barts and The London Medical School in London.
The beetroot juice contained about
0.2g of dietary nitrate, levels one might find in a large bowl of lettuce or
perhaps two beetroots. In the body the nitrate is converted to a chemical
called nitrite and then to nitric oxide in the blood. Nitric oxide is a gas
that widens blood vessels and aids blood flow.
"We were surprised by how
little nitrate was needed to see such a large effect," Ahluwalia said.
"This study shows that compared to individuals with healthy blood pressure
much less nitrate is needed to produce the kinds of decreases in blood pressure
that might provide clinical benefits in people who need to lower their blood
pressure. However, we are still uncertain as to whether this effect is
maintained in the long term."
The study involved eight women and
seven men who had a systolic blood pressure between 140 to 159 millimeters of
mercury (mm Hg), did not have other medical complications and were not taking
blood pressure medication. The study participants drank 250 mL of beetroot
juice or water containing a low amount of nitrate, and had their blood pressure
monitored over the next 24 hours.
Blood pressure is typically recorded
as two numbers. Systolic blood pressure, which is the top number and the
highest, measures the pressure in the arteries when the heart beats. Diastolic
blood pressure, the bottom and lower number, measures blood pressure in the
arteries between heart beats.
Compared with the placebo group,
participants drinking beetroot juice had reduced systolic and diastolic blood
pressure -- even after nitrite circulating in the blood had returned to their
previous levels prior to drinking beetroot. The effect was most pronounced
three to six hours after drinking the juice but still present even 24 hours
later.
In the United States, more than 77
million adults have diagnosed high blood pressure, a major risk factor for
heart diseases and stroke. Eating vegetables rich in dietary nitrate and other
critical nutrients may be an accessible and inexpensive way to manage blood
pressure, Ahluwalia said.
Getting people to eat more fruits
and vegetables is challenging, but results of the study offer hope, she said.
"In the U.K., the general public is told that they should be eating five
portions of fruit or vegetables a day but this can be hard to do. Perhaps we
should have a different approach to dietary advice. If one could eat just one
(fruit or vegetable) a day, this is one more than nothing and should be viewed
as positive."
The USDA recommends filling half
your plate with fruits and vegetables, and the American Heart Association
recommends eating eight or more fruit and vegetable servings every day.
Want more efficient muscles? Eat your beets and spinach
After
taking a small dose of inorganic nitrate for three days, healthy people consume
less oxygen while riding an exercise bike. A new study in the February, 2011
issue of Cell Metabolism traces that
improved performance to increased efficiency of the mitochondria that power our
cells.
The
researchers aren't recommending anyone begin taking inorganic nitrate
supplements based on the new findings. Rather, they say that the results may
offer one explanation for the well-known health benefits of fruits and
vegetables, and leafy green vegetables in particular.
"We're
talking about an amount of nitrate equivalent to what is found in two or three
red beets or a plate of spinach," said Eddie Weitzberg of the Karolinska
Institutet in Sweden. "We know that diets rich in fruits and vegetables
can help prevent cardiovascular disease and diabetes but the active nutrients
haven't been clear. This shows inorganic nitrate as a candidate to explain
those benefits."
In
fact, up until recently nitrate wasn't thought to have any nutritional value at
all. It has even been suggested that this component of vegetables might be
toxic. But Weitzberg and his colleague Jon Lundberg earlier showed that dietary
nitrate feeds into a pathway that produces nitric oxide with the help of
friendly bacteria found in our mouths. Nitric oxide has been known for two
decades as a physiologically important molecule. It opens up our blood vessels
to lower blood pressure, for instance.
The
new study offers yet another benefit of nitrate and the nitric oxides that stem
from them. It appears that the increased mitochondrial efficiency is owed to
lower levels of proteins that normally make the cellular powerhouses leaky.
"Mitochondria normally aren't fully efficient," Weitzberg explained.
"No machine is."
Questions
do remain. The new results show that increased dietary nitrate can have a
rather immediate effect. But it's not yet clear what might happen in people who
consume higher levels of inorganic nitrate over longer periods of time.
Weitzberg says it will be a natural next step to repeat the experiment in
people with conditions linked to mitochondrial dysfunction, including diabetes
and cardiovascular disease, to see if they too enjoy the benefits of nitrates.
"Among
the more consistent findings from nutritional research are the beneficial
effects of a high intake of fruit and vegetables in protection against major
disorders such as cardiovascular disease and diabetes," the researchers
concluded. "However, the underlying mechanism(s) responsible for these
effects is still unclear, and trials with single nutrients have generally
failed. It is tempting to speculate that boosting of the nitrate-nitrite-NO
pathway may be one mechanism by which vegetables exert their protective
effects."
As
an interesting aside, Weitzberg says that the benefits of dietary nitrates
suggest that powerful mouthwashes may have a downside. "We need oral bacteria
for the first step in nitrate reduction," he says. "You could block
the effects of inorganic nitrate if you use a strong mouthwash or spit [instead
of swallowing your saliva]. In our view, strong mouthwashes are not good if you
want this system to work."
The
group has also recently shown that nitrate reduces the blood pressure of
healthy individuals and that in laboratory animals it counteracts components of
the metabolic syndrome, a pre-stage of diabetes. Other scientists have
demonstrated protective effects of nitrate and nitrite in animal models against
heart attack and stroke.
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