Think, Re-Think, Re-Solve

Is bacon giving you cancer?
by Anastasia Quintana -- March 4th, 2016

bacon - free public domain photo

You may remember the hubbub from last October when IARC (the International Agency for Research on Cancer) linked red and processed meat consumption with cancer. Depending on how much you investigated the topic, you may have been left wondering, “So, what’s the deal?” If you’ve been wondering this, read on; I’ve looked it up for you and have summarized it below.

The short answer (from IARC 2015): yes, processed meat is pretty certainly linked with cancer (think: bowel cancer, but also possibly pancreatic and prostate cancer). Red meat is probably linked with cancer. What’s the cancer risk? For every extra 50 grams of processed meat (about 1 serving) that you add to your daily diet (that’s 50 extra grams every day), the risk of bowel cancer goes up by 18%.

bacon - from free public domain

Ok, first things first: definitions. What does IARC mean by red and processed meat?

Processed meat: meat that has been transformed through “salting, curing, fermentation, smoking” and more, including processed red meat and processed white meat (IARC 2015). Examples: hot dogs, ham, sausages, beef jerky, and yes: bacon.

Red meat: any mammalian muscle meat (IARC 2015). Examples: beef, pork, lamb, and goat.

processed meat - free public domain photo

And what exactly did they say about these? Here is an excerpt from IARC’s press release (IARC 2015):

“After thoroughly reviewing the accumulated scientific literature, a Working Group of 22 experts…classified the consumption of red meat as probably carcinogenic to humans (Group 2A), based on limited evidence that the consumption of red meat causes cancer in humans and strong mechanistic evidence supporting a carcinogenic effect. This association was observed mainly for colorectal cancer, but associations were also seen for pancreatic cancer and prostate cancer. Processed meat Processed meat was classified as carcinogenic to humans (Group 1), based on sufficient evidence in humans that the consumption of processed meat causes colorectal cancer…The experts concluded that each 50 gram portion of processed meat eaten daily increases the risk of colorectal cancer by 18%.”

red meat - free public domain photo

The risk

So, between red meat and processed meat, processed meat is more strongly linked (by the studies we have, anyway) to cancer. But to really understand what it means that ‘each extra daily serving of processed meat increases bowel cancer risk by 18%’, it is important to understand what your risk of bowel cancer is in the first place. Casey Dunlop, of Cancer Research UK, gives a nice discussion of this (Dunlop 2015), and you can check out his visual depiction here (http://zniup3zx6m0ydqfpv9y6sgtf.wpengine.netdna-cdn.com/wp-content/uploads/2015/10/151026-Tobacco-vs-Meat-TWITTER.png):

“We know that, out of every 1000 people in the UK, about 61 will develop bowel cancer at some point in their lives. Those who eat the lowest amount of processed meat are likely to have a lower lifetime risk than the rest of the population (about 56 cases per 1000 low meat-eaters). If this is correct, the WCRF’s analysis suggests that, among 1000 people who eat the most processed meat, you’d expect 66 to develop bowel cancer at some point in their lives – 10 more than the group who eat the least processed meat.”

red meat - free public domain image

OK, so we would statistically expect 10 more people out of every 1000 people (in the UK at least) to get bowel cancer from processed meat. But let’s zoom out a little more and put all this in perspective. Specifically, let’s compare the worldwide deaths from meat as compared to other causes (all statistics are from Dvorsky 2015 unless otherwise noted):

Cause                                                                    Deaths per year, worldwide

Unprovoked shark attacks (from ISAF 2014)                                              10

Processed meat                                                                                34,000

Red meat                                                                                             50,000

Malaria (from WHO 2015)                                                                    450,000

Alcohol                                                                                                     600,000

Smoking                                                                                                1,000,000

 

Can you avoid cancer by buying local or organic red and processed meat?

Sadly, the answer seems to be: no. Although the mechanism is still not perfectly understood, IARC has suggested that it is chemicals that are essential components of red meat (e.g. haem iron) that are carcinogenic (IARC 2015, Dvorsky 2015). For more information about the mechanism, read here (http://gizmodo.com/heres-why-you-shouldnt-panic-over-processed-meats-causi-1738704617 ) and here (http://scienceblog.cancerresearchuk.org/2015/10/26/processed-meat-and-cancer-what-you-need-to-know/ ).

processed meat - free public domain image

Great. So what can you do?

  1. The easiest way to reduce your risk for bowel cancer is to reduce your red and processed meat consumption. As Dunlop (2015) says: “our advice on diet stays the same: eat plenty of fibre, fruit and vegetables; cut back on red and processed meat, and salt; and limit your alcohol intake. It might sound boring but it’s true: healthy living is all about moderation.” Interestingly, according to the American Cancer Society, “about one third of cancer deaths can be attributed to poor diet and physical inactivity” (ACS 2016) – and so diet really does mean something in your cancer risk.
  2. It’s hard to find a “magic number” for red meat consumption, but you may understandably want something concrete. If so, feel free to consider this recommendation by the UK’s National Health Service (http://www.nhs.uk/Livewell/Goodfood/Pages/meat.aspx) which says that you should eat no more than 70 grams (2.5 oz) of red and processed meat a day.
  3. If you are looking for alternatives, right now there is no strong link between white meat and cancer, so consider switching to white meat some of the time

processed meat 2 - free public domain image

Finally, if you’re wondering why the red meat/cancer linkage is making it onto a socio-environmental blog, the answer is that (1) our food is part of our very local environment, and one of the ways that we interact indirectly with large swaths of land, and (2) red meat is a longstanding carbon emissions concern.

steak - free public domain image

Note: The photos in this post are all free public domain photos found on MorgueFile (http://www.morguefile.com/).

Cited

American Cancer Society (ACS). 2016. “Lower your cancer risk by eating right.” http://www.cancer.org/myacs/newengland/lower-your-cancer-risk-by-eating-right

Dunlop, Casey. 2015. “Processed meat and cancer – what you need to know.” Science Blogs, Cancer Research UK. http://scienceblog.cancerresearchuk.org/2015/10/26/processed-meat-and-cancer-what-you-need-to-know/

Dvorsky, George. 2015. “Here’s why you shouldn’t panic over processed meats causing cancer.” Gizmodo. http://gizmodo.com/heres-why-you-shouldnt-panic-over-processed-meats-causi-1738704617

International Association for Research on Cancer (IARC) 2015. “Press Release No. 240: IARC Monographs evaluate consumption of red meat and processed meat.” World Health Organization. http://www.iarc.fr/en/media-centre/pr/2015/pdfs/pr240_E.pdf

International Shark Attack Files (ISAF). 2014. “Worldwide Unprovoked Shark Attacks and Rate of Fatality.” http://www.flmnh.ufl.edu/fish/isaf/shark-attacks-maps-data/trends/attacks-fatalities/

World Health Organization (WHO). 2015. “10 facts on malaria.” Fact Files. http://www.who.int/features/factfiles/malaria/en/

1 Comment

  1. Leslie Pardue
    Mar 4, 2016

    Animal agriculture is also a huge contributor to climate change due to methane emissions. It has a greater impact than the entire transportation sector. It’s unsustainable for a growing human population. We can feed more people, achieve better nutrition, reduce greenhouse gas emissions and improve animal welfare by choosing a plant-based diet. The NS can lead the way at Duke by changing the menus for all of its events to plant-based menus, and publicizing the reasons for the change. It would be wonderful to see more attention paid to this issue by the NS administration.

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