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Red and processed meat, the new asbestos? Not really.

Recently, there was quite a lot of brouhaha about red and processed meat, after its appearance in the IARC's cancer list. Prevent asked me if I wanted to write an opinion piece about it. As a physician in preventive and occupational medicine, I have strong views about this subject, so I enthusiastically accepted. The article appeared recently in PreventActua.

The setting
The IARC (International Agency for Research on Cancer), part of the WHO, published a press release on October 26. This states that a group of experts, after a thorough review of the scientific literature, has decided that there is sufficient evidence to classify red meat as probably carcinogenic to humans (Group 2A), and processed meat as [definitely] carcinogenic to humans (Group 1).

Now, this very same press release also states that the individual risk remains small. That this information is rather of public health importance, given that there are so many people globally who eat meat. That these findings have been known since longtime and that they confirm existing recommendations. That red meat also has nutritional value. That governments and other organizations should weigh up the advantages and disadvantages of red and processed meat to draw up a balanced nutritional advice (which by the way, the High Health Council in Belgium for example has already done in 2013).

Unfortunately, such nuances were lost in the first wave of sensationalist coverage by the international press. Afterwards, the IARC was blamed for the resulting controversy. It was stated to be its fault, because it was not clear enough in its communications. And honestly, nowadays who still reads the second half of a whole page?

What is the IARC and what are these groups?
The IARC is the International Agency for Research on Cancer, and is part of the WHO (World Health Organization, or WHO). A group of experts studies the available scientific information on specific substances, manufacturing, food, lifestyles and environmental factors. The experts preferably choose items suspected to be very carcinogenic, or whose exposure is to such an extent that even a slightly increased risk of cancer can have a major impact on public health.

These items are then classified into one of five categories, depending on the certainty that they are carcinogenic. Whether the associated cancer risk is small or large doesn’t matter for the classification, only the certainty that there is a link. And this information can thus be used by governments and other official bodies to carry out a sound policy.

Five groups
The items in group 1 are definitely carcinogenic for humans. Again, that doesn’t automatically mean that it poses an immediate or important threat, only that there is enough proof for an increase in (slight, moderate or important) risk of cancer in humans. Processed meat is the newest member of the family of 118, which already included for example smoking, asbestos, alcohol, postmenopausal estrogen therapy, air pollution and sunlight. The list of course also includes many lesser known chemicals that are nonetheless important in production processes, but for your reading pleasure, I have omitted such examples. Oh all right, just the one then: 4-[(4-amino-3-chlorophenyl)methyl]-2-chloroanilin). I warned you!

Group 2 is divided into 2A (probably carcinogenic to humans) and 2B (possibly carcinogenic to humans). Group 2A contains 75 items, such as working as a hairdresser, performing shift work and as we all know now, since recently the list also contains eating red meat. Group 2B is made up of 288 products, with some interesting examples as working as a firefighter or welder, exposure to electromagnetic radiation, drinking coffee, and also products containing aloe vera or ginkgo biloba. Yes, those last two illustrate that with great beauty comes great sacrifice...

Group 3 is, well, frankly, a clutter group. It contains substances that the IARC has looked into, but for which they had to conclude that there is insufficient evidence to say whether they are or are not carcinogenic. No less than 503 topics are in this group, mostly little known chemical substances but for example also caffeine, drinking tea, exposure to glass and rock wool and using implants. So: can these items give you cancer? Ehh... maybe... but then again, also maybe not.
Group 4 finally contains materials that are considered by to IARC to be (probably) not a carcinogen. At the time of this writing, this group contains a grand total of ... one! And the winner is - drum roll - caprolactam. Which, as you undoubtedly know, is the best known representative of the lactams and is used, among other things, in the production of Nylon 6.

What does the IARC-advice mean?
A daily consumption of 50g of processed meat increases risk of colon cancer by 18%, the IARC estimates. But what does this mean, and what should we do with this information?

In Belgium, an average of 61 people in 1000 develop bowel cancer. Your individual risk varies of course, based on confounding factors such as genetic predisposition. But on average, you have a risk of 6.1% to get colon cancer over the course of your life. If based on the recent news items, you’ve decided to go completely vegan, then you still have a risk of at least 5.6% on average to develop bowel cancer nonetheless. And you'll also have to consider other risks due to your complete meat ban, such as a vitamin B12 deficiency leading to anemia (the scientific term is "pernicious anemia") and irreversible nerve and brain damage (a very serious condition, sometimes described as "management material").

On the other hand, if the whole of Belgium would consume on average 50g of processed meat less per day, we would avoid each year approximately 1000 cancer cases. The reverse is also true: if we as a nation start to eat more processed meat (which we can see happening right now in several Asian countries), the number of avoidable bowel cancers will also increase. Hence the advice of the IARC to weigh the pros and cons of eating red and processed meat, and to develop a policy on the basis of this knowledge.

The press release of the IARC was deliberately misunderstood by the sensationalist press. The classification of red and processed meat as respectively probably and definitely carcinogenic, only confirms long known scientific information, which has moreover already been implemented in several countries in a sound health policy.

To conclude, I want to give the following afterthought. If the entire population of Belgium, as a good intention for 2016, would decide to quit smoking (as you might recall, a long-time resident of group 1 in IARC’s list), we would each year avoid amply more than 10,000 cancers, and almost 20,000 smoking-related deaths on the whole. So, if you could all just do this one thing, I will allow you your slice of salami on your sandwich ...

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