A fifth of people suffer digestive problems because of work-related stress.

More than one in ten (16 per cent) have also suffered constipation or diarrhoea just before a big presentation at work.

And other triggers that lead to stomach problems include driving tests (ten per cent) and feeling nervous before a job interview (25 per cent).

About half of the 1,281 people questioned for a survey, published today, also said they felt stressed at least every other day.

Of those who suffered digestive problems as a result, more than 70 per cent experienced them regularly, with a third having them at least once a week.

The most common stress-related digestive problem was diarrhoea (32 per cent), followed by stomach ache (26 per cent) and irritable bowel syndrome (IBS) at 18 per cent.

The research, carried out on behalf of Yakult, was launched to coincide with Gut Week, which aims to raise awareness of digestive problems.

Warren Alexander, chief executive of the charity Core which is supporting the week, said: "This survey demonstrates how common digestive problems are.

"Although we are working hard to reduce the taboo of digestive health, people still turn a blind eye to symptoms associated with the gut, perhaps largely because of ignorance and embarrassment.

"Many people are suffering in silence from illnesses that could be treated and occasionally these symptoms might point towards a more serious problem."

Dr Nick Read, medical adviser to the charity IBS Network, added: "We were not surprised that the recent survey revealed IBS to be in the top three digestive complaints suffered as a result of stress.

"Diagnosis of IBS is on the increase with stress cited as a key trigger in many cases.

"Our newly-launched self-management programme offers guidance on how you can reduce symptoms of IBS by identifying and working through the stress in your life and managing your emotions."

Gut Week advisers can be contacted on 0208 743 4287 until Sunday, September 3. Lines are open from 6pm to 10pm all week and from 10am until midday on Saturdays.

The Gut Week website can also be found at www.gutweek.org.uk.