Processed meat & cancer update

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“Does bacon cause bowel cancer? Does red meat cause stomach cancer?”

In a short answer, yes, according to The World Health Organisation (WHO). They have labelled processed meats as carcinogenic agents. But what does this mean? Do we have to stop eating bacon and sausage? Shock and horror! Read on…

This is not new science. Epidemiological evidence and the underlying mechanisms have been studied in depth over the past few years. It is just now that the WHO and the IARC have exposed their new results that people are taking note again.

The background of IARC Monograph program:

Specialists from around the world assess a wide range of 940 agents from air pollution to solar radiation to chemicals and food products. The assessment looks at the hazard (how capable an agent is of causing cancer) not the actual risk (how likely it is to cause cancer). This is based on epidemiological studies, animal studies and underlying mechanisms.

The agent is then graded into 5 different groups depending on the level of evidence available.

Processed meat has been graded into group 1 – meaning that the agent is carcinogenic to humans, based on epidemiological evidence and animal studies.

Red meat has been graded as 2A (the agent can probably cause cancer), based on animal studies and limited epidemiological human studies.

At this stage it is important to look at what constitutes processed meats. It is made mostly from pork or beef meat that are preserved by treatment methods including curing and smoking, and yes most bacon and biltong are included here. Have a look at the image below…

cancerous_meat_624

 

The underlying mechanisms of how these products are associated with cellular changes and cancer are outlined by Santarelli et al in 2008 in the article Processed meat and colorectal cancer: a review of epidemiologic and experimental evidence, published in Nutrition and Cancer. 2008; 60(2): 131–144.

  • Cooking meat at a high temperature forms carcinogenic heterocyclic amines and polycyclic aromatic hydrocarbons
  • Carcinogenic N-nitroso compounds are formed in meat and endogenously
  • Heme iron in red meat can promote carcinogenesis because it increases cell proliferation in the mucosa
  • Nitrosation might increase the toxicity of heme in cured products

This science has been available for many years and may stand true. However in certain studies risk can be falsely linked to disease due to compounding factors. For example, the healthy well part of the population may avoid processed meats and be highly active and not smoke – all of which reduces their cancer risk.

I would like to highlight the following here.

It is important to realize that even though processed meat has been regarded as a grade 1 carcinogenic hazard, which also lists tobacco smoke, alcohol and solar radiation, their association to causing cancer is not the same. So you cannot compare the hazard that processed meat has on cancer to smoking for example. This is highlighted here:

3% of all cancers may be linked to red or processed meats

19% of all cancers may be linked to smoking cigarettes

(Cancer Research, UK)

 

Furthermore, there are positive attributes to eating red meat including the provision of high quality and bioavailable protein, zinc, vitamin B12.

It is also important to examine your source of processed and red meat and to opt for hormone free, grass fed, free-range meats.

The message is that we should find balance: limit the amount of processed meat in our diets and enhance a healthy, active lifestyle where weight is well managed, tobacco and excessive alcohol consumption is avoided and a diet high in antioxidants and nutrients is followed.