Eating even moderate amounts of red and processed meat increases the risk of bowel cancer, according to a study published today in the International Journal of Epidemiology.

The study showed that people eating on average around 76g of red and processed meat a day, which is roughly in line with UK Government recommendations, still had a 20% higher chance of developing bowel cancer than those who only ate on average about 21g a day.

One in 15 men and 1 in 18 women born after 1960 in the UK will be diagnosed with bowel cancer in their lifetime. This study found that risk rose 19% with every 25g of processed meat (roughly equivalent to a rasher of bacon or slice of ham) people ate per day, and 18% with every 50g of red meat (a thick slice of roast beef or the edible bit of a lamb chop).

Professor Tim Key, co-author of the study and Deputy Director of the Cancer Epidemiology Unit, Nuffield Department of Population Health, said: ‘Our results strongly suggest that people who eat red and processed meat four or more times a week have a higher risk of developing bowel cancer than those who eat red and processed meat less than twice a week.

‘There is substantial evidence that red and processed meat are linked to bowel cancer, and the World Health Organization classifies processed meat as carcinogenic and red meat as probably carcinogenic. Most previous research looked at people in the 1990s or earlier, and diets have changed significantly since then, so our study gives a more up-to-date insight that is relevant to meat consumption today.’

Professor Key and co-authors Dr Kathryn Bradbury, University of Auckland, and Dr Neil Murphy, International Agency for Research on Cancer, studied the diets of nearly half a million British men and women participating in the UK Biobank study. Participants aged 40 to 69 when the research began were followed over more than five years, during which time 2,609 of them developed bowel cancer.

Existing evidence points to an increased bowel cancer risk for every 50g of processed meat a person eats per day, but this research found that risk increases at just 25g per day, showing a similar rise in risk at smaller intervals. This is one of the largest single studies in the field and one of few to measure meat quantities and associated risks so precisely.

Dr Julie Sharp, Cancer Research UK’s Head of Health Information, said: ‘The government guidelines on red and processed meat are general health advice and this study is a reminder that the more you can cut down beyond this, the more you can lower your chances of developing bowel cancer.’

The researchers also found that alcohol was associated with an increased risk of colorectal cancer. Fibre from bread and cereals was associated with a reduced risk. More data are required to define the relative risks of different meats more clearly.