OPINION: Is bacon as bad as tobacco

THIS week the International Agency for Research on Cancer (IARC), the cancer agency of the World Health Organisation, released a report on the link between meat consumption and cancer risk. This led to some very interesting headlines in the online and mainstream media. 

These varied from the sensationalist “Processed meat as bad as smoking!” to the minimalising “Agriculture Minister plays down WHO’s findings ranking meat as cancer-causing as tobacco”. Although they are completely opposite sentiments, neither of these interpretations of the report is very helpful in letting everyday people know what the science is. 

My first surprise was that anyone was surprised. Yes, a new report was released, but the evidence of the potential risks associated with excess consumption of processed and red meat has been stacking up for some time now. 

The second thing that hit me was that most of the media coverage was extreme in one direction or the other, and I felt the actual point of the report was getting lost. The tone seems to be either “well doesn’t EVERYTHING cause cancer?” or “eating bacon will kill you”.  

I don’t know if the sensationalism is just a deliberate ploy to hook readers, or is just a consequence of poor communication of the science, but this media frenzy left me aching to put a few points straight. 

First, is eating meat as bad for you as smoking or asbestos? 

No. Smoking, asbestos and now processed meat, are listed in the same IARC category, which is carcinogenic to humans (Group 1). This has been oversimplified by many to mean “meat is as bad for you as smoking”.

But this is not true. The IARC classifies carcinogens in five categories ranging from carcinogenic to humans (Group 1) to probably not carcinogenic to humans (Group 4).  In the middle we have probably carcinogenic (Group 2A), possibly carcinogenic (Group 2B) and unclassifiable (Group 3). The classification does not rate level of risk or “badness” of the agents, but simply the strength of the scientific evidence showing that the agent can cause cancer. 

Being in the same category doesn’t mean two agents are equally as likely to give you cancer, just that we are equally as sure that they can cause cancer. In fact, the Q&A document issued with the press release for the report specifically warned against comparing agents in the same group.

So, does eating processed meat “cause” cancer?

While “cancer causing” is what carcinogen means, it is important to know that these results are not for all cancers, but are mainly for colorectal (bowel) cancer, with some associations for prostate and pancreatic cancers. 

Also, the findings were that increased consumption of processed meat increases your risk of cancer. Specifically, the report said that “each 50 gram portion of processed meat eaten daily increases the risk of colorectal cancer by 18%”. Increased risk is often misunderstood. It certainly doesn’t mean that everyone who eats processed meat will get colorectal cancer and everyone who doesn’t will always be free from cancer. It means if all other factors are equal, your cumulative risk is higher.

But all factors are never equal, there are all kinds of other risk factors for bowel cancer (age, activity level, family history, genes, exposure to other carcinogens) and these will be different in all of us. This doesn’t mean we should dismiss the risk, but it also doesn’t mean we should panic. It’s a numbers game and these reports are about giving people the information they need to improve their numbers. 

The human body is an amazing thing; it has molecular pathways that protect us by processing and eliminating disease causing agents, including carcinogens. But these systems can only protect us to a point, and there is no real way of knowing when you have exhausted that protection. This is why we talk about increased risks and not in absolute certainties.

What is it in red and processed meat that increases cancer risk?

The cancer causing agents can occur naturally in meat, or can be introduced through additives, cooking or digestion. Much is still yet to be figured out, but suspects include nitrates and nitrites – chemicals that are naturally produced when meat is cured or digested, and that are also added to processed meats.

 The heme iron in red meat is also thought to encourage chemical reactions in the body that produce other dangerous compounds, such as N-nitroso compounds and aldehydes. Cooking meat at high temperatures also produces other chemicals such as heterocyclic amines (HCAs) and polycyclic aromatic hydrocarbons (PAHs).  

If you are eating too much meat, you might also be eating less fibre rich foods, and fruits and veggies, and we know populations who have diets high in these foods have a reduced cancer risk. 

So enjoy your meats in moderation, but also enjoy fish, vegetables, fruits, legumes, grains and dairy. And don’t dismiss the reports as scientists just telling you another thing you love will kill you.

Emma Beckett  is a PhD candidate (food science) Human Molecular Nutrition Laboratory,  School of Environmental and Life Sciences, University of Newcastle