A study of more than 10,300 civil servants found that under-50s who suffered chronic stress had a 68 percent higher risk of heart disease than those who were not stressed at work.

The study, published in the European Heart Journal, provides the strongest evidence yet of the way stress can lead to heart disease.

The researchers, from University College London, found that 32 percent of the effect of stress on heart disease was down to eating badly and a lack of exercise.

But the rest was made up of biological factors caused by stress, which in the long-term can damage the heart.

The research -- part of the Whitehall II study which has been following London-based staff since 1985 -- examined the heart health of the civil servants taking part.

They found that high levels of stress had an impact on the autonomic nervous system, which regulates involuntary actions in the body such as the actions of the heart.

Those who suffered the most stress had lowered heart rate variability, suggesting that their heart rate was not dropping after exposure to stressful situations.

Dr. Tarani Chandola, lead author of the study, said: "If you are chronically exposed to stress it is not a good thing.

"The body is designed to deal with stressful situations, but the important thing is that it returns to baseline levels as soon as possible because of the damage stress hormones can do over a long period of time.

"It is good to have a lot of heart rate variability, as it shows you can react quickly to stress. But what we found was that in people with high levels of stress, there was less variability.

"Over the long term, this can damage the heart and increase the risk of heat disease."

The researchers also found that stressed workers had higher than normal morning levels of the stress hormone cortisol, which can also affect the heart over long periods.

In theory, doctors could test stressed workers for these early signs of heart disease risk.

Dr. Chandola said they also found that work stress was linked with people eating a poorer diet and taking less exercise -- all factors which could also raise the risk of heart disease.

He said their findings highlighted the need to make tackling work stress a priority.

June Davison, of the British Heart Foundation, said: "This contributes to our understanding of how stress at work may increase the risk of heart disease.

"It takes another step towards deciphering how stress may alter our body's chemistry to affect our heart health."

Source: The Scotsman. Provided by ProQuest Information and Learning. Powered by Yellowbrix.

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