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The bacon and cancer study, explained in 400 words

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News stories are constantly warning people that certain foods or behaviors might cause cancer. Sometimes the headlines even flip back and forth. So what are we to make of this latest announcement that scientists have linked meat consumption to certain types of cancers? Is this the real deal, or more hype?

The short answer is that, yes, this is a real finding. But — and this part is important — it's also a very narrow finding that needs to be interpreted cautiously.

In preparing its announcement today, the World Health Organization's International Agency for Research on Cancer (IARC) didn't just rely on a single study. The group reviewed all the existing evidence, including many years of epidemiological research, on processed and red meats to determine whether they lead to cancer in humans.

After reviewing that data, the group concluded "there is convincing evidence" that regularly eating processed meat — like hot dogs or salami — can definitely increase the risk of certain types of cancer by a small amount. The group also said there was suggestive evidence that eating unprocessed red meat — such as beef, veal, and lamb — could increase one's cancer risk, but this evidence wasn't as definitive. (So the researchers classified red meat as "probably carcinogenic.")

Now, this doesn't mean that red meat is much better than processed meat or vice versa — just that we're less certain about how dangerous it is. Still, because this finding was based on many studies in different contexts conducted over many years, it's far more likely to hold up. So this isn't just a run-of-the-mill news story about a single study that will be contradicted two weeks later.

The findings were also extremely narrow...

The WHO's IARC didn't come out and say that eating any sort of meat will cause all kinds of cancer. Nor did it claim processed meat is just as dangerous as smoking. The conclusions were far, far narrower: They have to do with cancer (mainly colon and rectal cancers) and meat.

The panel also didn't say anything about any of the other health or environmental risks (or potential benefits) of eating red meat.

So keep that all in mind. The IARC is making a narrow claim about the strength of the research around a specific question ("Does eating red meat increase your risk of cancer?") It is not making a claim about the relative risks, or about whether you should eat meat or not. Those are more complicated, and separate, questions.

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