Dr Ian Johnson, a nutrition researcher at the Institute of Food Research, said in a briefing given to the Science Media Centre that "the classification reflects the strength of the evidence for an effect", not how big that effect is. "The effect is much smaller than, for example, that of cigarette smoking on the risk of lung cancer." He pointed out that "there is little or no evidence that vegetarians in the UK have a lower risk of bowel cancer than meat-eaters".
Prof Tim Key, Cancer Research UK's epidemiologist at the University of Oxford, said in a statement: "We've known for some time about the probable link between red and processed meat and bowel cancer, which is backed by substantial evidence.
"This decision doesn't mean you need to stop eating any red and processed meat. But if you eat lots of it you may want to think about cutting down. You could try having fish for your dinner rather than sausages, or choosing to have a bean salad for lunch over a BLT."
The UK's Department of Health already recommends that people limit their intake of red and processed meat to 70g a day.
Tom Chivers is a science writer for BuzzFeed and is based in London.
Contact Tom Chivers at firstname.lastname@example.org.
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