Over the past week, several people have asked me about recent news related to red meat and processed meat causing cancer. Could it be true? Is it really as dangerous as smoking? Do I need to stop using my grill?

While the association between red meat and cancer is not new information, a recent systematic review presented at the International Agency for Research on Cancer (IARC) has both categorized the risk and reignited the conversation among healthcare professionals and the public. Here are some related definitions and a summary of the results that the researchers shared:

• Red meat is unprocessed mammalian muscle meat, including beef, veal, pork, lamb, mutton, horse, or goat meat. 
• Processed meat has been transformed through salting, curing, fermentation, smoking, or other processes.
• The group looked at “more than 800 epidemiological studies that investigated the association of cancer with consumption of red meat or processed meat in many countries, from several continents, with diverse ethnicities and diets.” (You can read more specifics on the studies in The Lancet Oncology. Free registration on the site is required). 
• Overall conclusions: 

“Overall, the Working Group classified consumption of processed meat as “carcinogenic to humans” (Group 1) on the basis of sufficient evidence for colorectal cancer. Additionally, a positive association with the consumption of processed meat was found for stomach cancer.”

“The Working Group classified consumption of red meat as “probably carcinogenic to humans” (Group 2A). In making this evaluation, the Working Group took into consideration all the relevant data, including the substantial epidemiological data showing a positive association between consumption of red meat and colorectal cancer and the strong mechanistic evidence. Consumption of red meat was also positively associated with pancreatic and with prostate cancer.”

So what does this mean? 

The evidence groups assigned by IARC refer to how likely a particular cancer risk is to actually cause cancer. Group 1 carcinogens (processed meat, smoking, alcohol) are classified as definite causes; Group 2a carcinogens (red meat, shift work) are classified as probable causes. But remember, it’s all about how confident the IARC is that something causes cancer, not how much cancer results.

This analogy shared by Cancer Research UK makes this a little easier to understand:  

“To take an analogy, think of banana skins. They definitely can cause accidents – but in practice this doesn’t happen very often (unless you work in a banana factory). And the sort of harm you can come to from slipping on a banana skin isn’t generally as severe as, say, being in a car accident. 

But under a hazard identification system like IARC’s, ‘banana skins’ and ‘cars’ would come under the same category – they both definitely do cause accidents.”

So while processed meat and tobacco are in the same Group 1 category – known to cause cancer – the risk of cancer from tobacco use is much higher than the risk of cancer related to eating processed meat. (You can see some great infographics here). 

Am I going to stop eating red meat?

No, I’ll still enjoy the occasional hamburger or hot dog. When it comes to meat, I already opt for chicken, turkey or fish more often than red meat, so I do feel pretty good about the balance in my current diet. And of course, I try to get plenty of fruits and vegetables too!

Has this recent report influenced you to make any changes to your diet? How do you answer patients (and friends and family) when they ask you “Should I stop eating meat?”

References 
Bouvard, V., Loomis, D., Guyton, K., Grosse, Y., Ghissassi, F., Benbrahim-Tallaa, L., . . . Straif, K. (2015). Carcinogenicity of consumption of red and processed meat. The Lancet Oncology.
Dunlop, C. (2015, October 26). Processed meat and cancer - what you need to know. Retrieved from Cancer Research UK: http://scienceblog.cancerresearchuk.org/2015/10/26/processed-meat-and-cancer-what-you-need-to-know/ 
World Health Organization. (2015, October 29). Links between processed meat and colorectal cancer. Retrieved from World Health Organization: http://www.who.int/mediacentre/news/statements/2015/processed-meat-cancer/en/
World Health Organization. (2015, October). Q&A on the carcinogenicity of the consumption of red meat and processed meat. Retrieved from World Health Organization: http://www.who.int/features/qa/cancer-red-meat/en/