A bacon sandwich. Bacon might cause cancer, but the risk is nowhere near as high as from smoking. Photograph: Anthony Devlin/PA Guardian

Meat and tobacco: the difference between risk and strength of evidence

This article is more than 8 years old

Comparing smoking to bacon in terms of risk of cancer is extremely misleading, despite the strength of evidence being similar

Vegetarians are probably breathing a sigh of relief today as headlines are warning us that processed and cured meats cause cancer. But the way this message has been framed in the media is extremely misleading.

Comparing meat to tobacco, as most news organisations who’ve chosen to report this have done, makes it seem like a bacon sandwich might be just as harmful as a cigarette. This is absolutely not the case.

The headlines are referring to the news that the World Health Organisation has classified cured and processed meats (bacon, salami, sausages, ham) as group 1 carcinogens, because there is a causal link between consuming these meats and bowel cancer. This group also includes tobacco, alcohol, arsenic and asbestos, all known to cause certain cancers.

But just because all these things cause cancer, doesn’t mean they’re all as risky as each other. A substance can increase your risk of cancer a small amount, or, like tobacco, a huge amount. Comparing them like for like is just really confusing to anyone trying to work out how to lead a healthy life.

These brilliant infographics from Cancer Research UK illustrate this perfectly. The risk of lung cancer from smoking is extremely high. Of all cases of lung cancer (44,488 new cases in the UK in 2012), evidence suggests that 86% of these are caused by tobacco. And lung cancer isn’t the only type of cancer caused by smoking. CRUK estimate that 19% of all cancers are caused by smoking. Another way of looking at this is that if smoking was completely eliminated, there would be 64,500 fewer cases of cancer in the UK per year.

CRUK infographic — CRUK’s infographic comparing tobacco and processed meat in terms of cancer risk Photograph: Cancer Research UK

In contrast, the recent evidence that suggests a causal link between processed meat and bowel cancer estimates that 21% of bowel cancers (which occurs at slightly lower rates than lung cancer – 41,600 new cases in 2011) were caused by eating processed and red meat. If all such meat was eliminated entirely from our diet, they estimate that 8,800 cases of cancer would be prevented in the UK per year.

All this simplistic reporting ignores a variety of other factors – the amount you consume, for example, is likely to affect your risk a great deal. And that’s not to mention addiction – however much you crave a bacon sandwich at times, it doesn’t contain nicotine.

The WHO have deemed the strength of evidence that processed meats cause cancer to be equivalent to that showing that smoking causes cancer. This means that if you eat a lot of red or processed meats you are increasing your risk of cancer. But to compare it to something as lethal as smoking is confusing and dangerous.

Read more about the details of the WHO’s report on the Cancer Research UK blog here.