Scientists have found that two glasses of orange juice a day can lower blood pressure and cut the risk of heart disease.

They discovered that middle-aged men who drank half-a-litre of juice every day for a month, equivalent to about two glasses, saw a significant decline in their blood pressure readings.

Findings confirm the presence of a natural plant chemical called hesperidin – part of a class of disease-fighting compounds found in plant foods like tea, fruit, soya and cocoa.

High blood pressure, which puts our arteries under greater pressure when the heart beats, affects one in five people and is one of the major risk factors contributing to a cardiac arrest.

The World Health Organisation estimates that 50 per cent of all heart attacks and strokes are due to raised blood pressure.

Guidelines state that the ideal limit for blood pressure is a systolic reading – the pressure inside the arteries when blood is forced through them – of 140mmHg.

To test their theory that it is hesperidin that gives orange juice its cardiovascular benefits, scientists at the University of Auvergne in France recruited 24 overweight but otherwise healthy middle-aged men.

Each one spent four weeks drinking half-a-litre of orange juice every day, followed by four weeks where they drank sweetened water and took a capsule containing hesperidin.

In the final four weeks of the experiment, they drank the same water and took a dummy capsule that had no hesperidin in it.