Hot dogs, bacon, other processed meats cause cancer, WHO declares

A research division of the World Health Organization said Monday that bacon, sausage and other processed meats cause cancer, and that red meat probably does, too.

The report by the influential group stakes out one of the most aggressive stances against meat yet taken by a major health organization, and it is expected to face stiff criticism in the United States.

The WHO conclusions are based on the work of a 22-member panel of international experts that reviewed decades of research on the link between red meat, processed meats and cancer. The panel reviewed animal experiments, studies of human diet and health, and cell mechanisms that could lead from red meat to cancer.

But the panel’s decision was not unanimous, and by raising lethal concerns about a food that anchors countless American meals, it will be controversial. The $95 billion U.S. beef industry has been preparing for months to mount a response and some scientists, including some unaffiliated with the meat industry, have questioned whether the evidence is substantial enough to draw the kinds of strong conclusions that the WHO panel did.

“We simply don’t think the evidence supports any causal link between any red meat and any type of cancer,” said Shalene McNeill, executive director of human nutrition at the National Cattlemen’s Beef Association.

The research into a possible link between eating red meat and cancer — colorectal cancer is a longstanding area of concern — has been the subject of scientific debate for decades. But by concluding that processed meats cause cancer, and that red meats “probably” cause cancer, the WHO findings go well beyond the tentative associations that other groups have reported.

The American Cancer Society, for example, notes that many studies have found “a link” between eating red meat and heightened risks of colorectal cancer. But it stops short of telling people that the meats cause cancer. Some diets that have lots of vegetables and fruits and lesser amounts of red and processed meats have been associated with a lower risk of colorectal cancer, the American Cancer Society tells the public, but “it’s not exactly clear” which factors of that diet are important.

Likewise, the Dietary Guidelines for Americans, the federal government’s advice compendium, encourage the consumption of protein foods such as lean meats as part of a healthy diet. Regarding processed meats, however, the Dietary Guidelines do offer a tentative warning: “Moderate evidence suggests an association between the increased intake of processed meats (e.g., franks, sausage, and bacon) and increased risk of colorectal cancer and cardiovascular disease,” the guidelines say. The Dietary Guidelines stop well short of saying processed meats cause cancer, however.

In recent years, meat consumption has been the target of multi-faceted social criticism, with debates erupting not just over its role on human health, but the impact of feedlots on the environment and on animal welfare. The public debate over the WHO’s findings will likely play out in political lobbying, and in marketing messages for consumers.

But at its core, the dispute over meat and cancer revolves around science, and in particular the difficulty that arises whenever scientists try to link any food to a chronic disease. “Is everything we eat associated with cancer?” a much noted 2012 paper in the American Journal of Clinical Nutrition asked.

That paper reviewed the academic studies conducted on common cookbook ingredients. Of the 50 ingredients considered, 40 had been studied for their impact on cancer. Individually, most of those studies found that consumption of the food was correlated with cancer. When the research on any given ingredient was considered collectively, however, those effects typically shrank or disappeared.