Should we eat less red meat?

Eating less red meat could save 17,000 lives, reports The Daily Telegraph in response to a press release from the World Cancer Research Fund, a charity whose aim in life is to demonstrate that cancers are caused by diet.

Some certainly are. Prominent among the suspects are red meat and processed meat, both of which have been linked to an increased risk of colorectal cancers. WCRF urges people to eat less red meat and avoid processed meats altogether.

WCRF issued a press release about its new report embargoed for Monday morning, a good choice as daily newspapers are always anxious to find a “Sunday for Monday” story that doesn’t require too much work. This one could be written on Friday and left for those in charge on Sunday to slot into the paper.

Lots of papers took the hook: apart from The Daily Telegraph, they included the Daily Mail, The Guardian, the Daily Express, and a number of papers who published a different angle on the story, provided by the Press Association’s Jane Kirby – that a diet high in fibre protects against bowel cancer. Those publishing the PA story (or one along similar lines) included The Press and Journal, The Independent, The Western Mail, The Herald, The Daily Mirror, The Evening Times, and The Sun.

The WCRF’s website includes the press release and a link to the report, which is an update of a document first published in 2007. The research team has sought out papers that have been published since then to add weight to its  findings.

The effect is rather different from the impression given by the newspaper reports. The extra research may have strengthened the evidence for a link between both red and processed meat and bowel cancer, but it also had the effect of reducing the size of that risk. See Table, below. .


So the actual risk estimates are lower than they were at the time of the 2007 report, which included data up to 2005. The updated report adds ten new studies to the 14 that featured in the 2007 report. It produces more convincing estimates of the risk, with smaller confidence intervals, but a lower overall risk for red and – to a lesser extent - for processed meat.

The data on dietary fibre shows little change, with a relative risk of 0.90 for colorectal cancer for every 10 grams a day consumed, (0.89 for colon cancer and 0.91 for rectal cancer). There’s no reason to question any of this evidence.

I do question, however, the headline figures quoted by WCRF and its partner, the American Institute for Cancer Research, for the number of cases that could be prevented by dietary and behavioural change. WCRF quotes 43 per cent of cases, AICR 45 per cent, but without specifying what people would need to do to achieve this objective, or how large the change in risk of death would be for any individual.

Teresa Nightingale of WCRF says in the press release: “This latest report shows there is enough evidence to recommend that people can reduce their bowel cancel risk by consuming less red and processed meat and alcohol, having more food containing fibre, and by maintaining a healthy weight and being regularly physically active.

“This report confirms that bowel cancer is one of the most preventable types of cancer and we estimate that about 43 per cent of bowel cancer cases in the UK could be prevented through these sorts of changes. That is about 17,000 cases a year.”

I can’t find any mention in the report about this conclusion, how it was reached, and what it means. (The report is 855 pages long, so I may have missed it.) How much less red meat? How much less alcohol, and how much more fibre? Does it really mean eliminating all processed meat, such as bacon or ham, from the diet?

If, as one might suspect, implausible changes in personal behaviour have been assumed in order to achieve this figure (moving from the top quartile to the bottom quartile in red meat consumption, for example) then it is a misleading claim – a pity, since the report itself gives every evidence of having been properly carried out.

Still, the WCRF can’t be blamed for the Daily Telegraph, which says in the headline that 17,000 lives might be saved (it meant cases), and in the text that there are 15,000 deaths a year in the UK from bowel cancer. You can’t save more lives than there are deaths



                                                      Daily Telegraph, May 23 2011