One glass of beetroot juice a day significantly lowered blood pressure in people with high blood pressure.
The trial, conducted at Queen Mary University of London (QMUL) in the United Kingdom (UK), was funded by the British Heart Foundation.
This interesting study builds on previous research by this team and finds that a daily glass of beetroot juice can lower blood pressure in people with hypertension - even those whose high blood pressure was not controlled by drug treatment.
The researchers publish their findings in the journal Hypertension.
Beetroot contains high levels of inorganic nitrate. Other leafy vegetables - such as lettuce and cabbage - also have high levels of the compound, which they take up from the soil through their roots.
In the human body, inorganic nitrate converts to nitric oxide, which relaxes and dilates blood vessels.
For the trial, the research team at QMUL recruited 64 patients aged 18-85. Half of the patients were taking prescribed medication for high blood pressure but were not managing to reach their target blood pressure, and the rest had been diagnosed with high blood pressure but were not yet taking medication for it.
The patients were randomly assigned to one of two groups. One group consumed a daily glass (250 ml or around 8.5 oz) of beetroot juice, and the other group had the same except their beetroot juice was nitrate-free (the placebo).
The patients consumed the juice every day for 4 weeks. They were also monitored for 2 weeks before and after the study, bringing the total trial period to 8 weeks.
The trial was double-blind, which means neither the administering clinicians nor the patients knew whether the beetroot juice they were given was the placebo or the active supplement.
First study to show lasting reduction in blood pressure from dietary nitrate
During the 4 weeks they were taking the juice, patients in the active supplement group (whose beetroot juice contained inorganic nitrate) experienced a reduction in blood pressure of 8/4 mmHg (millimeters of mercury).
The first figure is the reduction in systolic pressure (when the heart is pushing) and the second figure is reduction in diastolic pressure (when the heart is relaxing).
For many patients, the 8/4 mmHg reduction brought their blood pressure back into the normal range.
In the 2 weeks after they stopped taking the juice, the patients' blood pressure returned to their previous high levels.
The team notes that this is first study to show evidence of a long-lasting reduction in blood pressure due to dietary nitrate supplementation in a group of patients with high blood pressure.
The patients in the active supplement group also experienced a 20% or so improvement in blood vessel dilation capacity and their artery stiffness reduced by around 10%. Studies show such changes are linked to reduced risk of heart disease.
There were no changes to blood pressure, blood vessel function or artery stiffness in the placebo group (whose beetroot juice did not contain nitrate) during the period of the study.
The authors note that the reduction achieved in the active supplement group is comparable to that of medication; the average reduction in blood pressure that a single anti-hypertension drug brings is 9/5 mmHg.
The study concludes:
"These findings suggest a role for dietary nitrate as an affordable, readily-available, adjunctive treatment in the management of patients with hypertension."
To put the importance of these findings in context, the authors note that large-scale observational studies show that for every 2 mmHg increase in blood pressure, the risk of death from heart disease goes up 7% and from stroke by 10%.
Natural products to lower blood pressure are 'more appealing' than pills
This research has proven that a daily inorganic nitrate dose can be as effective as medical intervention in reducing blood pressure and the best part is we can get it from beetroot and other leafy green vegetables.
In fact, one reason the findings are exciting is because increasing dietary nitrate is something patients can easily work into their daily lives and see a positive benefit.
It is hugely beneficial for people to be able to take steps in controlling their blood pressure through non-clinical means such as eating vegetables. We know many people don't like taking drugs life-long when they feel ok, and because of this, medication compliance is a big issue.
The possibility of using a natural product, rather than another pill, to help lower blood pressure, is very appealing.
The researches advise people looking to increase their daily nitrate intake not to boil vegetables because the nitrate dissolves in water. Instead, steaming, roasting or drinking in a juice all has a positive effect.
As for the next step, this was a small trial, and now what is needed is a larger study that tries to replicate the findings over a longer period with a much larger group of people with high blood pressure.
High blood pressure increases the risk of more dangerous health conditions. For instance, about 70% of people who have a first heart attack, about 80% of those who have a first stroke, and 70% of those with chronic heart failure have high blood pressure. Kidney disease is also a major risk factor for people with high blood pressure.
According to the Centers for Disease Control and Prevention (CDC), high blood pressure is either the primary cause of or contributes to 1,000 American deaths every day.
References:
1. Dietary nitrate provides sustained blood pressure lowering in hypertensive patients, Vikas Kapil, et al., Hypertension, doi:10.1161/HYPERTENSIONAHA.114.04675, published online 24 November 2014, abstract.
2. Queen Mary University of London news release, accessed 20 January 2015.
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