More than one in 15 men are at risk of developing the disease compared with one in 29 in 1975.
For women, the risk has risen by more than a quarter to one in 19, from one in 26 in the mid-1970s, according to figures released by Cancer Research UK.
Experts say a diet rich in red and processed meat and lacking in fruit and vegetables is partly to blame for the soaring levels.
Sara Hiom, director of health information at the charity, said: ‘An ageing population as well as changes in lifestyle have both led to more people developing cancer than a generation ago.
‘But even though the chances of getting the disease have increased in the population there are many ways that people can cut their own risk.
‘You can reduce your risk of bowel cancer by keeping a healthy weight, being physically active, eating a healthy diet that’s high in fibre and low in red and processed meat, cutting down on alcohol and not smoking.’
In 2008 there were 21,500 cases of bowel cancer diagnosed in men compared with 11,800 in 1975.
For women the numbers have gone up from 13,500 in 1975 to 17,400 three years ago.
Professor Peter Sasieni, the Cancer Research UK epidemiologist who produced the figures, said: ‘As people are living longer the numbers getting cancer have increased and the lifetime risk of developing bowel cancer has gone up.
The figures, published in the British Journal of Cancer, represent the ‘lifetime risk’ of getting the disease, a new method of calculation taking into account people who get cancer more than once or die from other diseases.
‘For some cancers, including bowel, the risk of cancer in the next ten years will be much higher for people in their 50s and 60s.
‘But if someone reaches their late 70s and hasn’t yet developed the disease then their risk of getting it during the rest of their lifetime is lower than their risk at birth.’
Survival rates have improved, however, with 50 per cent of bowel cancer patients now living for at least ten years, double the number in the early 1970s due to earlier diagnosis and improvements in surgical techniques.
Scientists warned earlier this year that eating less red meat could prevent 17,000 cases of bowel cancer in the UK every year.
Mark Flannagan, chief executive of the charity Beating Bowel Cancer, urged people who are offered screening to accept the offer. ‘It could save your life,’ he said.
‘But we must look at the positives. In around half of cases bowel cancer can now be beaten.’