The small scale study found that people with high blood pressure who drank 250ml of beetroot juice experienced a decrease in blood pressure of about 10 mm Hg.
Led by Professor Amrita Ahluwalia from The Barts and The London Medical School, UK, the research team suggested that while the nitrate found in the juice was low – at around 0.2g – it still had a significant effect.
"We were surprised by how little nitrate was needed to see such a large effect," Ahluwalia 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," she said.
However, the research team added that their preliminary findings do not yet suggest that supplementing the diet with beetroot juice would provide any health benefit.
"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,” said Ahluwalia. “However, we are still uncertain as to whether this effect is maintained in the long term."
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.
The small-scale 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.
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.
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 authors said.
The effect was most pronounced three to six hours after drinking the juice but still present even 24 hours later, they added.
Published online ahead of print, doi: 10.1161/HYPERTENSIONAHA.111.00933
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