London, UK. High blood pressure is a major deterrent to surgery. Nearly one in three US adults is affected, but it is a problem wihout obvious symptoms. A significant portion of those affected don't even know it is too high for safety. Left uncontrolled, high blood pressure can lead to stroke, heart attack, or heart or kidney failure. More than 25 per cent of the world's adult population are diagnosed as hypertensive, with an estimated increase to at least 29 per cent by 2025.

 

 

 

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The research team was led by Professor Amrita Ahluwalia (William Harvey Research Institute at Barts and The London School of Medicine) and Professor Ben Benjamin (Peninsula Medical School). The research findings appear in the journal Hypertension.

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The researchers discovered that drinking just 500 ml of beetroot juice a day can significantly reduce blood pressure. Professor Ahluwalia and her team found that in healthy volunteers blood pressure was reduced within just 1 hour of ingesting beetroot juice, with a peak drop occurring 3-4 hours after ingestion. Some degree of reduction continued to be observed until up to 24 hours after ingestion.

 

Researchers showed that the decrease in blood pressure was due to the chemical formation of nitrite from the dietary nitrate in the juice.

 

The nitrate in the juice is converted in saliva, by bacteria on the tongue, into nitrite. This nitrite-containing saliva is swallowed, and in the acidic environment of the stomach is either converted into nitric oxide or re-enters the circulation as nitrite. The peak time of reduction in blood pressure correlated with the appearance and peak levels of nitrite in the circulation, an effect that was absent in a second group of volunteers who refrained from swallowing their saliva during, and for 3 hours following, beetroot ingestion.

 

In demonstrating that nitrate is likely to underlie the cardio-protective effect of a vegetable-rich diet, the research of Professor Ahluwalia and her colleagues highlights the potential of a natural, low cost approach for the treatment of cardiovascular disease — a condition that kills over 110,000 people in England every year. Hypertension causes around 50 per cent of coronary heart disease, and approximately 75 per cent of strokes.

 

Professor Ahluwalia said "Our research suggests that drinking beetroot juice, or consuming other nitrate-rich vegetables, might be a simple way to maintain a healthy cardiovascular system, and might also be an additional approach that one could take in the modern day battle against rising blood pressure".

 

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Acute Blood Pressure Lowering, Vasoprotective, and Antiplatelet Properties of Dietary Nitrate via Bioconversion to Nitrite. Andrew J. Webb; Nakul Patel; Stavros Loukogeorgakis; Mike Okorie; Zainab Aboud; Shivani Misra; Rahim Rashid; Philip Miall; John Deanfield; Nigel Benjamin; Raymond MacAllister; Adrian J. Hobbs; and Amrita Ahluwalia. Hypertension. February, 2008. doi: 10.1161 / HYPERTENSIONAHA.107.103523.

 

Abstract. Diets rich in fruits and vegetables reduce blood pressure (BP) and the risk of adverse cardiovascular events. However, the mechanisms of this effect have not been elucidated. Certain vegetables possess a high nitrate content, and we hypothesized that this might represent a source of vasoprotective nitric oxide via bioactivation. In healthy volunteers, approximately 3 hours after ingestion of a dietary nitrate load (beetroot juice 500 mL), BP was substantially reduced (max -10.4/8 mm Hg); an effect that correlated with peak increases in plasma nitrite concentration. The dietary nitrate load also prevented endothelial dysfu induced by an acute ischemic insult in the human forearm and significantly attenuated ex vivo platelet aggregation in response to collagen and ADP. Interruption of the enterosalivary conversion of nitrate to nitrite (facilitated by bacterial anaerobes situated on the surface of the tongue) prevented the rise in plasma nitrite, blocked the decrease in BP, and abolished the inhibitory effects on platelet aggregation, confirming that these vasoprotective effects were attributable to the activity of nitrite converted from the ingested nitrate. These findings suggest that dietary nitrate underlies the beneficial effects of a vegetable-rich diet and highlights the potential of a "natural" low cost approach for the treatment of cardiovascular disease.

 

 

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