The International Agency for Research on Cancer (IARC), the cancer agency of the World Health Organization, has evaluated the carcinogenicity of the consumption of red meat and processed meat.

Red meat

After thoroughly reviewing the accumulated scientific literature, a Working Group of 22 experts from 10 countries convened by the IARC Monographs Programme classified the consumption of red meat as probably carcinogenic to humans (Group 2A), based on limited evidence that the consumption of red meat causes cancer in humans and strong mechanistic evidence supporting a carcinogenic effect.

This association was observed mainly for colorectal cancer, but associations were also seen for pancreatic cancer and prostate cancer.

Processed meat

Processed meat was classified as carcinogenic to humans (Group 1), based on sufficient evidence in humans that the consumption of processed meat causes colorectal cancer.

Meat consumption and its effects

The consumption of meat varies greatly between countries, with from a few percent up to 100% of people eating red meat, depending on the country, and somewhat lower proportions eating processed meat.

The experts concluded that each 50 gram portion of processed meat eaten daily increases the risk of colorectal cancer by 18%.

“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,” says 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.”

The IARC Working Group considered more than 800 studies that investigated associations of more than a dozen types of cancer with the consumption of red meat or processed meat in many countries and populations with diverse diets.

The most influential evidence came from large prospective cohort studies conducted over the past 20 years.

Public health

"These findings further support current public health recommendations to limit intake of meat,” says Dr Christopher Wild, Director of IARC.

“At the same time, red meat has nutritional value. Therefore, these results are important in enabling governments and international regulatory agencies to conduct risk assessments, in order to balance the risks and benefits of eating red meat and processed meat and to provide the best possible dietary recommendations.”

Read the IARC Monographs Q&A on the carcinogenicity of the consumption of red meat and processed meat.

Response from Cancer Research UK

Professor Tim Key, Cancer Research UK's epidemiologist at the University of Oxford, said: "Cancer Research UK supports IARC's decision that there's strong enough evidence to classify processed meat as a cause of cancer, and red meat as a probable cause of cancer.

“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.

"Eating a bacon bap every once in a while isn't going to do much harm - having a healthy diet is all about moderation. 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.”

Reference

Bouvard, Loomis, Guyton et al. Carcinogenicity of consumption of red and processed meat, The Lancet Oncology, 26 October 2015

Source: IARC and CRUK