Bacon And Sausages Do Cause Cancer, Says World Health Organisation

Processed meats are now classed as a carcinogen.

The World Health Organisation (WHO) has said that processed meats, such as sausages and bacon, cause cancer.

The International Agency for Research on Cancer (IARC), part of the WHO, has released a report that reclassifies processed meats into "Group 1", "carcinogenic to humans". That means that there is "sufficient evidence in humans" that eating large quantities raises the risk of bowel cancer. Red meat has been classified as "probably" carcinogenic. The IARC based its report on more than 800 studies across various countries.

Group 1 also includes other known cancer-causing substances, such as tobacco and asbestos. However, the reclassification does not mean that eating red meat is as bad for you as smoking.

Previously, processed meat had been included in the IARC's "Group 2A", or "probably carcinogenic to humans", meaning that there was good evidence from animal trials and limited evidence from studies on humans that it caused cancer.

The IARC's experts concluded that every 50g of processed meat – roughly two slices of bacon – that you eat each day raises your risk of colorectal cancer by 18%. Dr Kurt Straif, the scientist in charge of the IARC's reports, said in a statement that "for an individual, the risk of developing colorectal cancer because of their consumption of processed meat remains small, but this risk increases with the amount of meat consumed".

According to Cancer Research UK, 64 people out of every 100,000 can expect to develop colorectal cancer per year. Taken crudely, the IARC's report suggests that eating 50g of bacon every day would raise your risk from 64 in 100,000 to 72 in 100,000, or from 0.064% to 0.072%. Over a lifetime, your risk is about 5%, according to the NHS; eating 50g of processed meat a day will raise that to about 6%.

For comparison, research on smoking and cancer found that men who smoked 25 cigarettes a day were 24 times higher risk of developing lung cancer, or a 2,400% increase.

Bhofack2 / Getty Images

Cancer Research UK / Via scienceblog.cancerresearchuk.org

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.