Put down the hot dogs and salami. WHO warns they cause cancer.

The Takeaway
A hot dog

Americans eat about 70 pounds of red meat each year. To cut back on cholesterol, calories, and unhealthy fats, the health community has urged consumers to reduce their red meat intake in recent decades.

But according to a new report released by the World Health Organization (WHO) on Monday, it looks like there’s a new reason to stay away from processed meats like bacon, corned beef, and hot dogs: Cancer.

A WHO panel reviewed decades of research and found a link between processed meats and colon cancer. But processed meat isn't the only problem — WHO also found evidence that red meat itself might be a carcinogen.

“There’s been evidence for several years that there’s an association between consumption of diets high in meat and different cancer types,” says Mariana Stern, a professor of epidemiology at the University of Southern California who contributed to this new WHO report. “What we did in this panel was to evaluate, comprehensibly, all of the available literature.”

Stern says that the WHO panel, which consisted of 22 experts from 10 countries, reviewed more than 800 scientific publications to conclude that red meat is a possible carcinogen, and that processed meat is a carcinogen.

“We found that there was sufficient evidence that processed meat can cause colorectal cancer,” Stern says. “The evidence for red meat was limited for colorectal cancer, for pancreatic cancer and prostate cancer.”

The researchers placed processed meat in the “Group 1” category. Under WHO guidelines, this means that there is convincing evidence that red meat causes cancer, though it's not as risky as other carcinogens in the group, such as tobacco smoking and asbestos exposure.

Red meat was classified in Group 2A, which means it is “probably carcinogenic to humans.” According to WHO, this designation was given “based on limited evidence from epidemiological studies showing positive associations between eating red meat and developing colorectal cancer.” In this case, according to WHO, “limited evidence” means that a positive association between red meat and cancer has been observed, but that other explanations could not also be ruled out.

So why is processed meat considered more carcinogenic than red meat?

“The actual mechanism by which this happens still needs to be established,” says Stern. “There are different strong hypotheses, and one of them is the presences of nitrates in processed meats, which can lead to damage in the intestines and potentially other parts of the body. The other is a mechanism that is common to both processed meats and red meats, which is the presence of haem iron, which can have different consequences.”

It’s unlikely that this report will drive all meat eaters to abandon steaks and BLTs. Though this WHO panel did not make dietary recommendations, Stern says the World Cancer Research Fund (WCRF) suggests that red meat consumption should be limited to about 18 oz per week.

“Currently, the American Cancer Society has similar recommendations to” WCRF, says Stern. “Now we’ll have to see whether other organizations in the US follow such recommendations, particularly in light of the findings of our working group.”

This story first aired as an interview on PRI's The Takeaway, a public radio program that invites you to be part of the American conversation.

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