The study, published in the International Journal of Epidemiology, showed that people eating around 76 g of red and processed meat a day – roughly in-line with recommendations from the UK Department of Health – still have a 20% higher change of developing bowel cancer than those who ate 21 g a day.
Researchers analysed data from the UK Biobank in a prospective cohort study of half a million men and women aged 40–69 years recruited from across the UK between 2006 and 2010. During this period, 2,609 participants developed bowel cancer.
They found that that risk rose 20% with every 25 g of processed meat, equivalent to a rasher of bacon or slice of ham, people ate per day. The likelihood of developing bowel cancer rose 19% with every 50 g of red meat, corresponding to a thick slice of roast beef or a lamb chop.
The study was partially funded by Cancer Research UK, alongside the UK Medical Research Council and others. It was co-authored by Cancer Research UK’s expert in diet and cancer, Professor Tim Kelly.
Professor Kelly, who is also deputy director at the University of Oxford’s cancer epidemiology unit, also revealed that people who eat red meat four times or more a week face a greater risk of developing bowel cancer.
“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,” he noted.
The study builds on previous research linking red meat to bowel cancer and, Professor Kelly suggested, helps provide a more up-to-date understanding of the causal relationship. “There’s substantial evidence that red and processed meat are linked to bowel cancer, and the World Health Organisation classifies processed meat as carcinogenic and red meat as probably carcinogenic – but 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.”
Existing evidence pointed to an increased bowel cancer risk for every 50 g of processed meat a person eats per day, but this research found that risk increases at just 25 g per day, showing a similar rise in risk at smaller intervals.
One in 15 men and 1 in 18 women born after 1960 in the UK will be diagnosed with bowel cancer in their lifetime.
Cancer Research UK’s head of health information, Dr Julie Sharp, said that the research should raise awareness that the government guidelines on red and processed meat are “general health advise”.
“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. This doesn't necessarily mean cutting out red and processed meat entirely, but you may want to think about simple ways to reduce how much you have and how often.”
‘Diet and colorectal cancer in UK Biobank: a prospective study’
International Journal of Epidemiology
Authors: Kathryn E Bradbury, Neil Murphy, Timothy J Key