Bacon and sausages feature, pigs in blankets

Processed meats such as hot dogs, bacon and sausages cause cancer, according to new research by the World Health Organization.

A report, published today (26 October) by the WHO’s International Agency for Research on Cancer, claimed consuming 50g of processed meat a day increases the chance of developing colorectal cancer by 18%.

It put processed meat on its group 1 list of carcinogens, alongside smoking, asbestos, diesel fumes, mustard gas and plutonium, while red meat was classified as “probably carcinogenic to humans” alongside herbicide glyphosate as a group 2A carcinogen.

The research was undertaken by a working group of 22 cancer experts from 10 countries, who assessed more than 800 epidemiological studies from around the world that investigated possible associations between cancer and the consumption of red or processed meat.

The working group said there was “sufficient evidence” that processed meat consumption causes colorectal cancer, with the large amount of data collected across different populations making chance, bias and confounding factors ”unlikely” as explanations. They also found a positive association between processed meats and stomach cancer.

The links between red meat and cancer were less clear, with a number of high quality studies failing to find any association, and confounding lifestyle factors more “difficult to exclude”.

The study acknowledged that red meat is a valuable protein source and contains important micronutrients such as B vitamins, iron and zinc.

However, it warned that meat processing, such as curing and smoking, can result in the formation of carcinogenic chemicals, including N-nitroso-compounds (NOC) and polycyclic aromatic hydrocarbons (PAH).

Cooking meat, particularly at high temperature such as pan frying, grilling, or barbecuing, also produces suspected carcinogens including heterocyclic aromatic amines (HAA) and PAH.

“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,” said Dr Kurt Straif, head of the IARC Monographs Programme. “In view of the large number of people who consume processed meat, the global impact on cancer incidence is of public health importance.”

“These findings further support current public health recommendations to limit intake of meat,” added IARC director Dr Christopher Wild. “At the same time, red meat has nutritional value.”

Not comparable to smoking

Cancer Research UK said it supported the IARCs decision that there was enough evidence to classify processed meat as a cause of cancer, and red meat as a probable cause of cancer.

However, it stressed this classification did not mean that eating processed meat was as dangerous as smoking, and urged people to cut down rather than give up on bacon and other processed products.

“Eating a bacon bap every once in a while isn’t going to do much harm - having a healthy diet is all about moderation,” said Professor Tim Key, Cancer Research UK’s epidemiologist at the University of Oxford.

“Overall red and processed meat cause fewer cases of cancer in the UK than some other lifestyle factors. And by far the biggest risk to your health is smoking – causing over a quarter of cancer deaths in the UK and nearly one in five cancer cases.”

Maureen Strong, nutrition manager for AHDB, said the government recommendation to limit red and processed meat consumption to 70g a day is based on the same evidence that the IARC reviewed. “That’s exactly what the vast majority of us are eating,” she said. “The government has already said that this advice is not changing.”

She added the IRAC concluded that eating 50g of processed meat brings a “small increase in risk”, but average UK consumption of processed meat is just 17g per day. “People would need to eat three times their current levels to increase their risk.”

The vast majority of British sausages and burgers would not be considered as processed meat – which is defined as meat that has been preserved by smoking, curing, salting or adding preservatives.