One glass of beetroot juice a day is enough to significantly reduce blood pressure in patients with high blood pressure, conclude researchers who conducted a placebo-controlled trial in dozens of patients.
Beetroot has been used since the Middle Ages as a treatment for ailments, particularly those relating to the blood and digestion. Medical researchers have recently returned to this plant product to investigate its potential effect on blood pressure.
Beetroot contains high levels of dietary nitrate (NO3), which the body converts into biologically active nitrite (NO2) and nitric oxide (NO). In the human body, NO relaxes and dilates blood vessels.
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.
High blood pressure is a serious public health concern; it increases the risk of more dangerous health conditions such as heart attack, stroke, and chronic heart failure. 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 more than 1,000 American deaths every day.
Because of the impact of high blood pressure on society, any simple dietary interventions that could be of benefit are likely to be researched in some depth.
Blood pressure and beetroot
Recent research shows that beetroot might reduce blood pressure in some people.
A meta-analysis of 16 trials was published in The Journal of Nutrition in 2013.
The researchers found that: "Inorganic nitrate and beetroot juice supplementation was associated with a significant reduction in systolic blood pressure."
Here we will discuss the latest study to investigate beetroot and its impact on blood pressure.
The trial was carried out at Queen Mary University of London (QMUL) in the United Kingdom and published in the journal Hypertension.
The study 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."
Dr. Shannon Amoils, British Heart Foundation, senior research advisor
For the trial, Amrita Ahluwalia, a vascular pharmacology professor at QMUL, and colleagues recruited 64 patients aged 18-85. Half of the patients were taking prescribed medication for high blood pressure but did not 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 milliliters or around 8.5 ounces) 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 that 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 mm Hg.
The first figure is the reduction in systolic pressure (when the heart is pumping) and the second figure is reduction in diastolic pressure (when the heart is relaxing and filling with blood). For many patients, the 8/4 mm Hg 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.
Should we all add beetroot to our diets?
The team notes that this is the 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 percent or so improvement in blood vessel dilation capacity and their artery stiffness reduced by around 10 percent. Studies show such changes are linked to reduced risk of heart disease.
There were no changes in 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 mm Hg.
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 mm Hg increase in blood pressure, the risk of death from heart disease goes up 7 percent and the risk of stroke increases by 10 percent.
Natural products to lower blood pressure are 'more appealing' than pills
Commenting on the findings, Prof. Ahluwalia says:
"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."
She says one reason the findings are exciting is that 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," Prof. Ahluwalia adds. "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," adds Dr. Amoils.
Prof. Ahluwalia advises 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," she notes. As for the next step, she says 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.