Decoding the WHO classification of red meat as carcinogenic

Should we stop consuming red meat entirely? Is processed meat as dangerous as smoking when it comes to causing cancer?


Processed meat was classified among agents which are “carcinogenic to humans” as there was sufficient evidence that consumption of processed meats causes colorectal cancer or bowel cancer. Photo: Bloomberg
Processed meat was classified among agents which are “carcinogenic to humans” as there was sufficient evidence that consumption of processed meats causes colorectal cancer or bowel cancer. Photo: Bloomberg

New Delhi: The International Agency for Research on Cancer (IARC) on Monday classified processed meat as carcinogenic to humans and red meat as probably carcinogenic.

But what do these two classifications mean? Should we stop consuming red meat entirely? Is processed meat as dangerous as smoking when it comes to causing cancer? How did the arm of the World Health Organization (WHO) come to these conclusions?

A working group of 22 experts from 10 countries were a part of the IARC Monographs Programme to decide the role played by meats in causing cancer. This programme, which identifies and evaluates environmental causes of cancer in humans, has till date reviewed more than 900 agents.

The IARC working group considered more than 800 different studies on cancer in humans which included more than 700 epidemiological studies on red meat and more than 400 epidemiological studies on processed meat.

The final verdict was that the consumption of red meat is “probably carcinogenic to humans”. The ‘probable’ classification is because of limited evidence, which means that although there is a positive association observed between exposure to the agent and cancer, there are other possible explanations for the observations such as technical bias or chance.

Processed meat, however, was classified among agents which are “carcinogenic to humans” as there was sufficient evidence that consumption of processed meats causes colorectal cancer or bowel cancer. These experts even concluded that each 50 gram portion of processed meat eaten daily increases the risk of bowel cancer by 18%.

Now, there are 117 agents alongside processed meat including tobacco smoke and asbestos that are considered carcinogenic. So is eating processed meat as dangerous as smoking?

IARC has emphasized that this does not mean that they are all equally dangerous. Two agents will be put in the same category to describe the strength of the scientific evidence regarding a substance causing cancer, but does not quantify the risk at the same levels.

IARC has, however, said that according to the Global Burden of Disease Project, about 34,000 cancer deaths per year worldwide are because of diets high in processed meat.

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.

IARC also explained that during meat processing, cancer-causing chemicals can form, including N-nitroso compounds and polycyclic aromatic hydrocarbons, while cooking of red meat or processed meat also produces heterocyclic aromatic amines as well as other chemicals which are all known or suspected to be cancer-causing agents.

So should we not eat meat at all? WHO is a little dodgy on this. While saying that eating meat has known health benefits, it added that many national health recommendations advise people to limit the intake of processed meat and red meat as they also increase risk of death from heart disease, diabetes, and other illnesses.

But WHO is yet to establish a safe limit for the consumption of these meats.

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