Researchers from Queen Mary University of London, Barts and The London School of Medicine and Dentistry have been looking at the benefits of beetroot for some years. Early research involved giving very high doses of beetroot juice to healthy volunteers.
Having found the juice helped lower blood pressure, they then pinpointed nitrate as the blood pressure lowering ingredient.
In the new study, after research on rats demonstrated that raising nitrate levels reduced blood pressure, 15 humans with high blood pressure drank 250 ml glasses of either nitrate-rich beetroot juice or an equal volume of water each day. The ones who had the beetroot juice experienced blood pressure reductions of around 10 mm Hg.
The reduction was highest around three to six hours after drinking the juice but still had an effect 24 hours later.
Lowering blood pressure
Beetroot was used as it was easy to make into a juice, but the researchers say other nitrate-rich vegetables including lettuce, cabbage and fennel are likely to have the same effect. However, they caution it is too soon to recommend any specific diet changes before a larger study, already under way, is completed.
The lead author of the study, Professor Amrita Ahluwalia tells us: "I don't think anybody would have liked it if we'd juiced lettuce leaves and cabbage.
"Beetroot isn't unique in being able to alter the cardiovascular system. Rocket has a very high inorganic nitrate content; fennel has a high inorganic content."
The research was funded by the British Heart Foundation. The charity's medical director, Professor Peter Weissberg says in a statement: "This promising study shows that it may be possible to reduce high blood pressure by eating more foods that contain large quantities of nitrates, such as green vegetables and beetroot. It supports current advice that we should all be eating plenty of green veg. But we need larger studies in patients to determine if nitrate-rich vegetables are effective at lowering blood pressure over the long term."
Eating nitrate produces another chemical in the body called nitrite, and in turn, nitric oxide, which Professor Ahluwalia says can do a lot of good: "It opens up blood vessels; allows blood to flow through the blood vessels more easily, which means the pressure, the resistance to flow in the body goes down. And that brings blood pressure down."
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