The International Agency for Research on Cancer (IARC), a research division of the World Health Organization, announced Monday that processed meats such as bacon, sausage, ham, and hot dogs cause cancer.

The organization also identified red meat as “probably carcinogenic,” meaning it’s likely to cause cancer as well.



Processed meats were classified as a Group 1 carcinogen to humans, in the same group as smoking tobacco and asbestos exposure. Substances in this group have “sufficient evidence” of carcinogenicity in humans, according to the IARC.

The findings were based on the work of a 22-member panel of experts from 10 countries. The panel reviewed more than 800 studies that investigated the link between more than a dozen types of cancer with eating processed meat or red meat in many countries with different diets. The most influential evidence came from studies conducted over the past 20 years, according to a press release from the IARC.

The experts concluded that each 50-gram portion of processed meat (less than 2 ounces) eaten daily increases the risk of colorectal cancer by 18 percent.

The IARC defines processed meats as “meat that has been transformed through salting, curing, fermentation, smoking, or other processes to enhance flavor or improve preservation.” Most processed meats contain pork or beef, it adds, but may also contain other red meats, poultry, offal (organs and entrails of an animal), or meat by-products.

Related: You’ll Be Surprised What Counts as Processed (and Red) Meat



Popular processed meats include sausage, jerky, bacon, hot dogs, and kebabs, along with everyday lunchmeat such as ham, salami, corned beef, pastrami, and bologna, as well as canned meats and packaged meat-based sauces.

Ham, hot dogs, and bacon have been singled out in a new international report linking processed meats with cancer. It’s the most aggressive stance by a regulatory agency yet, and the U.S. meat industry is taking exception. But many nutrition experts say the evidence is there. (Photo: Getty Images)



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Related: Hot Dogs May Contain Human DNA



Red meats include beef, veal, pork, lamb, mutton, horse, and goat.

The organization said that the individual risk of developing colorectal cancer from eating processed meats is “small” but increases with the amount of meat a person eats.

The panel also determined that eating 100 grams of red meat per day (about 4 ounces) may raise a person’s risk of colorectal cancer by 17 percent.

“This association was observed mainly for colorectal cancer, but associations were also seen for pancreatic cancer and prostate cancer,” the organization said.

The new declaration is one of the most aggressive stances taken by an international health organization and is, thereby, highly controversial — even within WHO itself. According to the Washington Post, the panel decision was not unanimous and is expected to face criticism within the United States, where processed and red meat still forms the base of most meals and is backed by a powerful lobbying industry.

The National Cattleman’s Beef Association, the trade association that represents U.S. cattle producers, put out a press release soon after the WHO announcement that — not surprisingly — questions the findings. “Most scientists agree that it is unrealistic to isolate a single food as a cause of cancer from a complex dietary pattern further confounded by lifestyle and environmental factors,” the association says in the release.

“The available scientific evidence simply does not support a causal relationship between red or processed meat and any type of cancer,” Shalene McNeill, executive director of human nutrition for the National Cattlemen’s Beef Association, said in the release.

But Andrew Chan, MD, an associate professor of medicine at the Harvard School of Public Health, disagrees. “The epidemiological data supporting an association between processed and red meats and colon cancer is very strong,” he tells Yahoo Health. “There is definitely some reason for caution about the consumption of red and processed meats.”

However, Anton Bilchik, MD, chief of medicine and gastrointestinal research at California’s John Wayne Cancer Institute, tells Yahoo Health that the new declaration is extreme. “To suggest that all red and processed meat is going to cause cancer and should be put in the same category as asbestos and smoking is irresponsible,” Bilchik says.

Unlike cigarettes or asbestos, Bilchik says there’s nutritional value to eating red meat — in moderation. Bilchik acknowledges colon cancer’s link to processed- and red-meat consumption but also says the cause of the disease is complex. “Diet may play a role, and there may be a genetic component,” he says. “As of now, we just don’t know which group of people should eat less red meat than others.”

Other organizations have encouraged people to eat less meat for better health but have stopped short of declaring that meat consumption causes cancer.

The American Cancer Society recommends limited red meats and processed meats. “Because of a wealth of studies linking colon cancer to diets high in red meats (beef, lamb, or liver) and processed meats (hot dogs, bologna, etc.), the Society encourages people to eat more vegetables and fish and less red and processed meats,” the ACS says on its website.

The Dietary Guidelines for Americans also recommends limiting consumption of processed meats due to “moderate evidence” that they cause an increased risk of colorectal cancer but also doesn’t declare that they cause cancer.

Related: The Science Behind Why We’re So Obsessed With Bacon



A study by the National Cancer Institute of 500,000 people found that those who ate red meat daily were 30 percent more likely to die during a 10-year period than those who ate very little red meat. Eating processed meats also increased the risk of death.

Christopher Wild, PhD, director of the IARC, acknowledges in a press release that red meat has nutritional value and does not say that people should avoid it altogether. Rather, the IARC encourages government agencies to “balance the risks and benefits of eating red meat and processed meat and to provide the best possible dietary recommendations.”

Chan also says people shouldn’t avoid red meat but should limit their intake. “It’s pretty clear that the link between consumption of meat with cancer appears to be dose-related,” he says. “The more you eat, the higher your risk.”

Chan says it’s “reasonable” to continue to include red meat in a balanced diet, provided it’s limited.

Read This Next: What Science Has to Say About Red Meat

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