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Last week, the International Agency for Research on Cancer released a report establishing a
link between eating processed meat, which I love, and cancer. Specifically, colorectal
cancer.
And you might have heard people saying things like, “Eating meat is as dangerous as smoking
cigarettes!” and “the World Health Organization has declared a war on deliciousness!”
But both of those extreme examples are a little misleading. There is no war on deliciousness.
The World Health Organization is not drafting you into an eternal conflict against the forces
of bacon. It’s not even telling you not to eat bacon. And processed meat is NOT as
carcinogenic as cigarettes.
The IARC is the cancer agency under the umbrella of the World Health Organization. And one
of their main goals is to identify stuff that causes cancer.
And now they’ve analyzed red meat -- the muscle of a mammal, like beef, pork, and lamb
-- and processed meat -- meat that’s been treated in some way before you cook it, like
sausage, hot dogs, and bacon.
They compiled the results of more than 800 epidemiological studies, which examine entire
populations of people for patterns, taking into consideration the mechanistic evidence
-- the stuff we can see happening under a microscope, or in a chemical reaction.
And what they concluded was that processed meat DOES cause cancer.
The IARC found that for every 50 grams of processed meat you eat, on average, per day,
your risk of developing colorectal cancer goes up by 18%.
That DOES NOT MEAN you have an 18% chance of developing that cancer!
According to current statistics: If you live in America, you have a 5% chance of developing
colorectal cancer at some point in your lifetime. That’s an average of everybody, no matter
their risk factors. And if you eat 50 grams of processed meat a day, that 5% chance becomes
5.9%.
Because .9 is 18% of 5. It’s an 18% increase to your starting cancer risk, not a flat 18%
increase in your chance to develop that cancer. Those are two totally different things.
So, yeah, if you eat a portion of bacon for breakfast every morning, your risk of developing
colorectal cancer is about 1% more than somebody who doesn’t. Does that mean you should stop
eating the bacon? I dont know...how much do you like it? It’s up to you.
Because the IARC concluded that processed meat definitely can cause cancer, they categorized
it as ‘Group 1,’ with all the other definite carcinogens.
The IARC’s categories are there to tell you the strength of the scientific evidence
saying that something can cause cancer. NOT how dangerous that something is.
So the Group 1 list does include stuff like cigarettes. It also includes plutonium. And
wood dust. And the soot from a home chimney.
Not all of those things are equally dangerous. In terms of health risk, I’ll take working
in a wood shop over a smoking habit any day. And processed meat is not one of the more
dangerous things on that list.
Red meat, on the other hand, was categorized as Group 2A. Those are things that are PROBABLY
carcinogens, but there isn’t enough evidence to say for sure.
While most of the evidence supported the hypothesis that red meat could also cause cancer, there
were too many well-designed studies that couldn’t establish a link.
So what is it about processed meat that can cause cancer?
Cancer happens when the DNA in one of your cells mutates or is damaged in a way that
causes it to replicate out of control. That runaway cell division forms a tumor, which
will keep growing even as it invades and destroys neighboring tissues.
Certain chemicals are formed in meat during the process of processing, and cooking the
meat can then produce even more chemicals.
These compounds are what’s dangerous, because they break down in your body to form free
radicals that can rip apart your DNA. These are ions that want to bond with the organic
molecules in your body. DNA is one of those things it can bond with.
Of these, the N-nitroso compounds, or NOCs, are the most dangerous.
They’re formed when the amino acids in meat are exposed to oxides of nitrogen, compounds
where a nitrogen atom and an oxygen atom are bonded together.
This exposure happens naturally during smoking, pickling, or drying. Like, during smoking,
the meat is exposed to the nitrogen in the smoke.
It can also happen when nitrates and nitrites are added on purpose, which many manufacturers
do, because those compounds prevent the growth of bacteria, like the kind that causes botulism.
But those oxides of nitrogen, bonded to amino acids, can form these N-nitroso compounds,
which are MASSIVELY bad for you and SUPER good at causing the DNA mutations that can
lead to cancer.
Like N-nitroso-dimethylamine, or NDMA, which is one of the most carcinogenic compounds
on Earth. It’s actually used by researchers to induce tumors in lab rats.
When your body metabolizes this stuff, NDMA breaks down into nitrite (NO2-) and methyl
radicals (CH3).
The nitrite bonds with other organic molecules in your cells to produce formaldehyde: the
stuff they used to use to embalm corpses until they stopped because it caused cancer.
And the methyl radicals...can do a lot of things, most of them bad, but they particularly
like to form bonds with guanine, which is one of the bases in your DNA.
When they do, they rip the guanine out of its bonds with the other bases, introducing
new, potentially cancerous errors.
So: can eating processed meat lead to cancer? Yes.
Should you stop eating it? I mean, if you’re eating pounds of hot dogs every day, yeah,
you might want to cut back.
But the new report doesn’t make any health recommendations. That’s not what it’s
for. The World Health Organization puts out these reports to keep people informed.
Which is also our goal, so I hope you are more informed now. That way, you can understand
what the risk is, and decide for yourself whether it’s worth it.
Thanks for watching this episode of SciShow News, and thanks especially to all of our
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