Processed meat carcinogenic to humans, says WHO agency’s study

IARC says red meat also has nutritional value, and hopes that the findings will help countries conduct assessments to provide the best possible dietary recommendations

By Karnika Bahuguna
Published: Tuesday 27 October 2015
Cutting a joint of roast beef Credit: Steve Johnson, Flickr

The International Agency for Research on Cancer (IARC), an agency of the World Health Organization (WHO), has stated in a study that consumption of processed meat is carcinogenic to humans and can cause colorectal cancer.

IARC evaluated the carcinogenicity of the consumption of red meat and processed meat.

A working group of 22 experts from 10 countries convened by the IARC Monographs Programme thoroughly reviewed scientific literature.

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

The group also classified the consumption of red meat as probably carcinogenic to humans.

The classification is based on “limited evidence” from epidemiological studies showing positive associations between eating red meat and developing colorectal cancer as well as strong mechanistic evidence, IARC said. Limited evidence means that a positive association has been observed between exposure to the agent and cancer but that other explanations for the observations (technically termed “chance”, “bias”, or “confounding”) could not be ruled out.

The Monographs Programme identifies and evaluates environmental causes of cancer including chemicals, complex mixtures, occupational exposures, physical agents, biological agents and personal habits in humans.

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

“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 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 working group of the IARC 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.

“These findings further support current public health recommendations to limit the intake of meat,” says 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.”


Frequently Asked Questions

What is red meat?
Red meat refers to all types of mammalian muscle meat, such as beef, veal, pork, lamb, mutton, horse, and goat.

What is processed meat?
Processed meat refers to meat that has been transformed through salting, curing, fermentation, smoking, or other processes to enhance flavour or improve preservation. Most processed meats contain pork or beef, but processed meats may also contain other red meats, poultry, offal, or meat by-products such as blood. Examples of processed meat include hot dogs (frankfurters), ham, sausages, corned beef, and biltong or beef jerky as well as canned meat and meat-based preparations and sauces.

What makes your meat carcinogenic?
High-temperature cooking methods generate compounds that may contribute to carcinogenic risk, but their role is not yet fully understood. Cooking at high temperatures or with the food in direct contact with a flame or a hot surface, as in barbecuing or pan-frying, produces more of certain types of carcinogenic chemicals (such as polycyclic aromatic hydrocarbons and heterocyclic aromatic amines). However, there were not enough data for the  working group of the IARC to reach a conclusion about whether the way meat is cooked affects the risk of cancer.

What makes red meat and processed meat increase the risk of cancer?
Meat consists of multiple components, such as haem iron. Meat can also contain chemicals that form during meat processing or cooking. For instance, carcinogenic chemicals that form during meat processing include N-nitroso compounds and polycyclic aromatic hydrocarbons. Cooking of red meat or processed meat also produces heterocyclic aromatic amines as well as other chemicals including polycyclic aromatic hydrocarbons, which are also found in other foods and in air pollution. Some of these chemicals are known or suspected carcinogens. But despite this knowledge, it is not yet fully understood how cancer risk is increased by red meat or processed meat.

Could the preservation method influence the risk (e.g. salting, deep-freezing, or irradiation)?
Different preservation methods could result in the formation of carcinogens (e.g. N-nitroso compounds), but whether and how much this contributes to the cancer risk is unknown.

Is eating raw meat safer?
There were no data to address this question in relation to cancer risk, said IARC. However, the separate question of risk of infection from consumption of raw meat needs to be kept in mind.

What types of cancers are linked or associated with eating red meat?
The strongest, but still limited, evidence for an association with eating red meat is for colorectal cancer. There is also evidence of links with pancreatic cancer and prostate cancer.

What types of cancers are linked or associated with eating processed meat?
The IARC Working Group concluded that eating processed meat causes colorectal cancer. An association with stomach cancer was also seen, but the evidence is not conclusive.

Should you stop eating meat?
Eating meat has known health benefits. Many national health recommendations advise people to limit intake of processed meat and red meat, which are linked to increased risks of death from heart disease, diabetes, and other illnesses.

Source: International Agency for Research on Cancer


Subscribe to Daily Newsletter :
Related Stories

Comments are moderated and will be published only after the site moderator’s approval. Please use a genuine email ID and provide your name. Selected comments may also be used in the ‘Letters’ section of the Down To Earth print edition.