Scientists from University College London (UCL) studied the biological rather than psychological effects of stress in 183 men aged between 45 to 63.

They focused on how much control they had in their work and looked at how they viewed their wealth.

The men were quizzed about their diet and alcohol and tobacco consumption.

Hormones

The study looked at changes to the nervous system and the production of stress hormones.

The results showed a link with "metabolic syndrome", which is thought to be a precursor to coronary heart disease.

Although this is not concrete proof that stress causes metabolic syndrome or indeed heart disease, we are certainly closer to proving it

Dr Eric Brunner

Dr Eric Brunner, who led the research, said: "This study provides biological and therefore more objective evidence than ever before of the link between stress and metabolic syndrome.

"Although this is not concrete proof that stress causes metabolic syndrome or indeed heart disease, we are certainly closer to proving it."

People with metabolic syndrome display a combination of at least three symptoms from obesity, high blood sugar, raised levels of triglycerides (a type of fatty acid found in the blood) and low levels of HDL, a so-called "good cholesterol".

Raised levels of triglyceride can increase the risk of coronary heart disease and stroke.

High cholesterol levels are risk factors for coronary heart disease and strokes.

Stress

The researchers said they were encouraged that the biological effects of stress were thought to be reversible if men reduced their risk factors, such as losing weight or lowering their blood pressure.

Professor Sir Charles George, medical director at the British Heart Foundation, which helped fund the study, said: "The link between stress and heart disease is still unclear but this study is significant as it helps us to understand more about the relationship between the conditions.

"Although more research is needed, this is an important step forward."