The research centres on endocannabinoids - natural substances produced by the body - which are chemically similar to the active ingredients in the drug.

These substances are known to make blood vessels relax, which can reduce blood pressure by allowing blood to flow more freely.

The effect has been observed, but little is known about how endocannabinoids are produced and how they cause changes in the body.

The study is being carried out by researchers in Nottingham, and is being funded with a �120,000 grant from the British Heart Foundation.

Effects

Dr David Kendall, from the Queen's Medical Centre in the city, said: "This research should tell us a great deal more about how these substances affect our circulation.

"This is a new and exciting area of research which could ultimately lead to better treatments for a range of cardiovascular diseases."

Professor Brian Pentecost, medical director of the British Heart Foundation, said the foundation was not encouraging drug abuse.

"These are natural substances, present in all our bodies, that seem to have important effects on our circulation," he said.

"Hopefully this project will shed new light on how we could use these effects to help heart patients."

Prevalence

High blood pressure, or hypertension, affects between 10% and 20% of adults in the UK.

It is linked to obesity, smoking, and in some cases, a high salt intake.

Hypertension puts a strain on the heart and blood vessels and greatly increases the risk of stroke and heart disease.