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Eating red and processed meat isn't going to increase your risk of cancer by that much

Contextualizing the World Health Organization's cancer report

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Yesterday, the World Health Organization threw everyone into a panic by releasing a report categorizing red and processed meat as cancer-causing agents. After reviewing 800 scientific studies, the WHO's International Agency for Research on Cancer (IARC) concluded that eating processed meats — such as bacon, deli meats, and sausage — definitively causes colorectal cancer, while eating red meats is "probably" carcinogenic.

Though this announcement may seem terrifying to the average meat lover, the IARC doesn’t provide much context for its new categorization. Yes, there is a link between consuming these foods and cancer, but the risk is incredibly small — much smaller than smoking cigarettes or being exposed to other known carcinogens. The report also doesn't identify if there is a safe level of meat to eat. Mostly, the IARC findings tell us that there is an established cancer risk associated with eating processed meats, albeit a minor one. It’s something that researchers have suspected for some time.

"The first thing to do is don’t freak out."

"The first thing to do is don’t freak out," said Tim Buyers, a professor of epidemiology at the Colorado School of Public Health. "We’ve known that for general health for a long time that it’s not a good idea to eat large amounts of red meat."

The IARC categorizes potential carcinogens in groups, based on what the scientific literature shows about their cancer-causing potential. With this new study, published in Lancet Oncology, the IARC officially classifies processed meats as a Group 1 Carcinogen. Items in this category are defined as "carcinogenic to humans," meaning "there is enough evidence to conclude that it can cause cancer in humans." Red meats got placed in Group 2A, meaning "there is strong evidence that it can cause cancer in humans, but at present it is not conclusive."

Group 1 Carcinogens contain a long list of items, including things that are almost impossible to avoid — such as sun exposure, exhaust fumes, and air pollution. Even alcoholic beverages are also listed in Group 1, having been linked to head and neck cancer, esophageal cancer, breast cancer, and more. Those who drink more than three alcoholic beverages a day significantly increase their risk of developing these conditions.

But just because something is listed as a Group 1 Carcinogen doesn't mean it's an incredibly potent carcinogen. The IARC concludes that if a person eats a 50-gram portion of processed meat per day, he or she increases the risk of getting colorectal cancer by 18 percent. "This is about the degree of risk increase from many other colon cancer risk factors, including obesity, physical sedentariness, and low vegetable or grain intake," said Buyers. So the main takeaway from this report is that moderation is key.

The risk of getting cancer from smoking cigarettes is much higher than consuming red and processed meats. (Paolo Neo/Wikimedia Commons)

And when you compare the risks associated with eating significant portions of processed meats versus the risks of smoking cigarettes — another Group 1 Carcinogen — you find the differences in risk are extreme. At the individual level, it’s impossible to say what specific agent caused a patient’s cancer, but statistically, researchers can estimate how many cancers within a large population are caused by specific factor. (The details are kind of technical but essentially researchers measure a group’s exposure to a potential carcinogen — then compare that to cancer rates in that group.) In the UK, for example, around 64,500 cases of cancer are linked to smoking, according to Cancer Research UK. That's compared to 8,800 cases of cancer that are linked to eating processed meat. In other words, smoking is responsible for a fifth of all cancers in the UK, while only 3 percent of cases are caused by red and processed meat.

Even people who were to cut processed meat from their diet entirely wouldn’t completely erase the risk of colorectal cancer, either. Suppose you followed 1,000 people over the course of their lifetimes; about 61 people would get colorectal cancer on average, according to Casey Dunlop, a health information officer at Cancer Research UK. Based on the IARC’s findings, if you were to follow a group of 1,000 people who ate the most red and processed meats throughout their lives, about 66 would get colorectal cancer. If you followed the 1,000 people who consumed the least red or processed meats, only 56 would get colorectal cancer. (Absolute amounts for both the top and the bottom groups of meat-eaters — like how many red or processed meats they would eat a day — weren’t part of these estimates.)

Cutting out processed meat from your diet entirely won't completely erase the risk of colorectal cancer

There are much more effective ways to reduce your risk of colorectal cancer. "I think [cutting out red and processed meats] would reduce your risk a little bit, but that is nothing like the size of the benefit of getting colonoscopies and removing polyps," said Buyers. "That act after age 50 can remove colon cancer risk by more than half."

That’s not to say you shouldn’t try to limit your intake of these foods. Many experts have advised people to reduce — not entirely cut out — the amount of red and processed meats in their diet in light of the report. If you're a big fan of steak and bacon, it may be a good idea to cut down on them or replace them with chicken and seafood. Dunlop also advises bulking up the vegetables you eat with each meal. That way, you eat smaller portions of red and processed meats and more foods that bring positive health benefits. However, red meat is a good source of iron, so there are still some reasons to keep these foods on your dinner plate.

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