A common bacteria found in the stomachs of millions of Britons could partly explain the disturbing rise in bowel cancer cases, new research suggests.Scientists say the bacterium, known as Helicobacter pylori (H. pylori), could be responsible for as many as one in five cases of the deadly disease. Around 40 per cent of people carry the bacteria in their stomach and it does not usually trigger symptoms.However in some, it can cause indigestion, bloating and nausea and, in worst cases, ulcers that can develop into stomach cancer. Now scientists have suggested those exposed to the bacteria - usually as a result of contaminated food - face a 60 per cent higher risk of colorectal cancer than those not exposed. The research throws open the possibility that antibiotics could be offered to high risk patients in a bid to prevent cancer developing. Publishing their findings in the journal eGastroenterology, scientists from the University of Hong Kong said: 'H. pylori control may help prevent gastric cancer and, if the link with bowel cancer is causal, reduce the burden of disease.' H. pylori live in the sticky mucus that lines the stomach Bowel cancer is one of 11 types that are increasing among young people.If current trends continue, colorectal cancer is projected to become the leading cause of cancer-related death among young adults by 2030. While obesity is the only known behavioural risk factor that is on the rise, experts say it is not sufficient to explain the overall rise. The current study suggests that harmful strains of H. pylori might be involved. Together with experts from the University of California, the Hong Kong researchers analysed health data from 43 studies, involving more than 48.7 million people worldwide.They found that people exposed to the bacteria had a 59 per cent higher risk of colorectal cancer than those not exposed.Using all available studies, the researchers estimated that 22 per cent of cases could potentially be linked to the bacteria.