A new report linking meat with cancer raises questions about america’s—and the world’s—eating habits.
Jens Mortensen for TIME
By Jeffrey Kluger
October 29, 2015

Americans love to talk about their freedoms. Most of the time they mean the familiar ones–speech and press and assembly, as well as the other high-minded things our forefathers made sure to include in the national contract. But there are other freedoms too–the freedom to be loud, the freedom to be large, the freedom to have an appetite for anything at all and then set out to satisfy it.

That’s the freedom of rock ‘n’ roll and Super Bowls and Talladega and rodeos, of settling a continent and then, still not sated, following up with a helping of Alaska and Hawaii too. And for many of us it’s also the everyday freedom, when we sit down at the table, to eat whatever we please. The modern American diet is a huge, sprawling, bib-under-the-chin affair of generous portions served up on demand. Most primally, that has meant a diet heavy in red meat and processed meat. The hamburger and the hot dog are as much national symbols as they are menu items (when Gemini 3 astronauts went into orbit in 1965, they smuggled up a corned beef sandwich and the nation had a good laugh).

Now this is being called into question by doctors, by public heath advocates and by the World Health Organization (WHO), which has not just Americans’ well-being in mind but also that of the entire globe–including country after country to which America has eagerly exported its diet. In a sweeping review released on Oct. 26, the WHO officially identified processed meat as a Group 1 carcinogen, meaning the quality of the evidence firmly links it to cancer. Red meats fare little better, falling into Group 2A–foods or substances that probably cause cancer–a category that includes the toxic pesticide DDT, the chemical weapon mustard gas and the insecticide malathion. (Groups 2B, 3 and 4 are foods or substances that are possibly carcinogenic, not yet classifiable as carcinogenic or probably not carcinogenic, respectively.)

This immediately sparked a round of apocalyptic headlines, including many variations of Hot Dogs As Bad For You As Cigarettes. Predictably, it also caused a lot of confusion for people who are trying to eat right but are buffeted by health recommendations that seem prone to being overturned years later. Because make no mistake: we like our meat. In 2013, the average American consumed more than 71 lb. of beef, lamb, veal and pork; last year, Americans ate a collective 24.1 billion pounds of beef alone. And what Americans don’t eat, they sell overseas, where economic growth has been matched by a demand for red meat. The U.S. is the world’s second biggest exporter of pork and fourth biggest of beef. Like movies and music, American meat reaches round the world.

But this may need to be rethought. The truth is, the link between meat and cancer is not entirely new to scientists, and the evidence for it has been growing for a while. For decades, health experts have warned that red and processed meats are linked to cardiovascular disease, obesity and various forms of cancer. The first two of those dangers have always made sense, and have caused some people to cut down or swear off meat. But the last part of the troika–the cancer part–has been hedged with uncertainty. No more.

So are we really talking about life without hot dogs and T-bones? The answer requires understanding not only what the science does–and doesn’t–say about risk but also factoring in the stakeholders in this debate. That’s a group that ranges from public health experts and consumer advocates to local farmers and giant agribusinesses–and the meat-loving public too. The fact is, lots of things are bad for us. Ultimately it’s about taking the best information and using it to make smart choices.

The categories of meat in the new study are broad and inclusive. Red meat is defined as “all types of mammalian muscle meat, such as beef, veal, pork, lamb, mutton, horse and goat.” So goodbye to pork’s claim to be “the other white meat.” Processed meats include “meat that has been transformed through salting, curing, fermentation, smoking or other processes to enhance flavor or improve preservation.”

That means, if you’re following the new guidance, the end of the turkey-bacon dodge–it’s still a processed food, and it’s still bacon–as well as the frisson of dietary virtue that comes from ordering smoked turkey instead of salami at the deli counter, because, well, it’s poultry.

The study, which was conducted by a respected WHO subsidiary, the International Agency for Research on Cancer (IARC), did not look at fresh poultry–not a great concern to public health experts, rather unanimously–but what it did say was worrisome to public health experts.

“According to most recent estimates,” the authors wrote, “about 34,000 cancer deaths per year worldwide are attributable to diets high in processed meat.” The study estimates a possible 50,000 deaths similarly attributable to red meat. Both of those numbers seem low compared to the 1 million deaths due to tobacco-related cancer. But in the U.S., there are about 2½ cases of colorectal cancer per year for every one death, which means that even if eating meat doesn’t kill you, it could still make you very sick. Some researchers are at least trying to put that troubling fact in a positive light.

“One way that I’m thinking about this finding is that it actually gives us the opportunity of identifying one of the many important factors that contribute to colorectal cancer that we can do something about,” says Dr. Mariana Stern, a cancer epidemiologist at the University of Southern California, who worked on the IARC paper.

No surprise, the meat industry is hitting back. According a statement by the North American Meat Institute (NAMI), a trade association that claims to represent companies that process 95% of U.S. red meat and 70% of turkey products, the new report “defies both common sense and numerous studies showing no correlation between meat and cancer. Scientific evidence shows cancer is a complex disease not caused by single foods.”

At NAMI headquarters in Washington, bosses greeted the IARC report in a uniquely meat-centric way: ordering breakfast tacos with bacon and chorizo for the entire staff. “It’s our own form of protest,” says Janet Riley, an industry spokeswoman and the president of the National Hot Dog and Sausage Council. “It’s pretty interesting, the reaction that consumers are having. There’s a lot of pushback.”

But the IARC report is a robust one. Much more than a single study, it is a so-called meta-analysis–a study of studies–evaluating 800 published papers. Twenty-two experts from 10 countries conducted the work and then voted on what findings to issue.

Those findings state that 50 grams of processed meat per day–one hot dog or about six pieces of bacon–raises the risk of colorectal cancer by 18%. Other cancers too were associated with red and processed meats, including stomach, prostate and pancreatic, but it was colorectal that produced the most persuasive numbers.

“We looked at a big reach of literature,” says Stern. “There was sufficient evidence that processed meat causes colorectal cancer. Based on the limited evidence and the strong mechanistic evidence, we concluded that red meat is a probable carcinogen.”

Warnings about meat go back a long way, but in recent years they’ve been piling up. An exhaustive 2007 study by the American Institute for Cancer Research and the World Cancer Research Fund pointed to a troubling link between animal protein and multiple forms of cancer. In 2009, a study sponsored in part by the National Institutes of Health (NIH) found that people who eat red and processed meats have a higher risk of dying of cancer, heart disease and other causes than people who don’t. A smaller 2011 meta-analysis funded by World Cancer Research Fund International found a link between red and processed meats and colorectal cancer, and a 2013 study with 47 co-authors from across Europe and elsewhere linked meat with both increased cancer and heart-disease mortality. Even taking all this into account, the new IARC research is easily the largest and most conclusive to date.

There’s a cruel irony to the fact that meat should be as dangerous as health experts warn, because we are hardwired to love every little thing about it. Predation is not just a nasty indulgence we picked up on our way through the state of nature; it’s a nutritional must-do, or at least it was in our ancestors’ times. Animal muscle is dense with proteins and other nutrients, and the fat from a cow or pig will serve the same purpose in our body as it did in its original owner’s: as a repository for calories in the event of a food shortage or famine. To make sure we come when the dinner bell clangs, our brains recognize the smell of sizzling meat as singularly irresistible.

But it’s in that sizzle that the trouble starts. Meats cooked at high heat produce what are known as polycyclic aromatic hydrocarbons (PAHs) and heterocyclic amines (HCAs). Both cause changes in DNA–and that can mean trouble. “Once you’re talking about DNA damage, that’s the origin of cancer,” says Dr. David Katz, director of Yale University’s Prevention Research Center. “With the right kind of mutation, the cell sort of escapes the normal oversight of replication. It becomes a rogue colony of cells, then it becomes a tumor.”

In the case of processed meats, the biggest risks are sodium nitrates, which are added to foods principally as preservatives. Once they enter the body, however, they form nitrosamines, chemical compounds that are carcinogenic. “It’s long been known that part of the processing of meats introduces carcinogens into the mix,” says Katz, “particularly nitrates.”

Even unprocessed red meats can lead to problems like this. Certain gut bacteria can convert otherwise benign components of meat to nitrosamines, Stern warns. What’s more, when meat is grilled enough to be charred–something that’s all but unavoidable on a lot of backyard barbecuers–carcinogens can form.

Oh, and if you think you’ve gotten around the nitrate-nitrite problem by buying hot dogs and other processed meats labeled no nitrates added, bad news: those products are treated instead with celery juice, which is naturally high in sodium nitrate. By themselves, most vegetables do contain nitrates–indeed, produce is the biggest source of dietary nitrate–but they also contain vitamin C, which inhibits nitrosamine production. But meats? Not so much.

Another factor in the red-meat mix is what’s known as heme iron, which is a type of iron bonded with a metabolic molecule known as protoporphyrin. Plants contain only nonheme iron; meats of all kinds contain both heme and nonheme. In the Western world, heme iron makes up 10% to 15% of all iron in the diet, which is a lot. A larger share of heme iron is absorbed by the body than nonheme, and in the time the stuff spends hanging around, it can reach the colon, causing potentially toxic reactions.

“The heme iron may have a direct effect on the cells in the large bowel,” says Stern. “These are all mechanisms that have been observed in both unprocessed and processed red meats.”

None of this comes at a good time for people who like to eat meat–to say nothing of those who make a living selling it. America has, of late, been in the grip of one of its periodic food fads, this one involving bacon. Bacon beer, bacon vodka, bacon milkshakes, bacon popcorn and, yes, bacon condoms–scented to smell like bacon and patterned to resemble it–have all hit the market. And none of that includes the proliferation of real bacon added to all manner of real dishes. It’s a bustling time for restaurants catering to our taste for beef too, with premium steak houses doing $7 billion worth of business in the U.S. last year.

Still, the 71 lb. of red meat we consume per capita is actually down from 96.3 lb. in 1970, with poultry picking up much of the slack. Those numbers provide their own evidence of the cancer-meat link, however, since rates of colorectal cancer have been in similar decline, going from 59.5 per 100,000 people in 1975 to 38 in 2012. Whether this is indeed a result of reduced red-meat consumption or simply better detection and intervention isn’t clear. All the same, the estimates are that there will be 96,090 new cases of colon cancer in the U.S. this year and 39,610 of rectal cancer.

Figures like that are not always easy to understand and can be more alarming than they need to be. The lifetime risk for developing colorectal cancer is just 5% for men and a little lower for women. A hot dog a day would raise that risk by 18% of the 5%–topping you out at about a 6% overall risk. But that assumes that’s all the red meat you ever eat, and those 1% increments add up fast.

The IARC report itself takes pains to put the findings in similar perspective, clearly defining the difference between a hazard and a risk–words that sound almost synonymous in ordinary language but are radically different in the context of epidemiology. “An agent is considered a cancer hazard if it is capable of causing cancer under some circumstances,” the report states. “Risk measures the probability that cancer will occur, taking into account the level of exposure to the agent.” In the same way, fire is an undeniable hazard to your home. The risk that the place will ever actually burn to the ground is another matter.

That’s a point seized on by the meat producers–and it’s a perfectly fair one. “The problem with cancer is that it occurs over a lifetime,” says Ceci Snyder, a registered dietitian and a spokeswoman for the Pork Board, an industry marketing group. Noting that a lot of other variables like blood pressure, obesity and exercise can play key roles in cancer and overall health, she added, “We cannot discount the confounding factors.”

Dave Warner, a spokesman for the National Pork Producers Council–the lobbying arm of the pork industry–took some comfort from the fact that the findings of the IARC were not unanimous. Seven of the 22 panelists either abstained from voting or openly disagreed with the findings. Still, the report did not require unanimity, and a supermajority of 68% confirmed its conclusions.

Whether any of this will have much impact on American health policy is impossible to say, but as with all things in Washington, following the money does provide some clues. Agribusiness contributed about about $800 billion to the American GDP in 2013, and pockets that deep buy influence. The sector spent over $127 million on lobbying activities last year, according to the Center for Responsive Politics, with nearly 1,000 registered lobbyists on the payrolls. Political-action committees and other advocacy groups sympathetic to the industry contributed another $77.2 million. Three-quarters of that money went to Republicans.

The Food and Drug Administration did not seem terribly exercised by the IARC study, noting that the federal government carries out its own such research through the National Toxicology Program. “The NTP Report on Carcinogens has not specifically looked at red meats or processed meats as whole food items,” says FDA spokeswoman Megan McSeveney. “These substances have not been nominated for review for the next edition of the Report on Carcinogens.” The Department of Agriculture released a statement in response to the IARC announcement, “encourag[ing] Americans to lead an overall healthy, active lifestyle and eat a healthy, balanced diet.”

But government nutrition recommendations are an ever changing thing. With the U.S. Department of Agriculture (USDA) set to release its 2015 dietary guidelines later this year, the hope among some health experts has been that the report will take a firmer hand with meat–particularly processed meat–and the IARC study may strengthen the case for that. The U.K. recommended that Britons who eat 90 grams or more of red or processed meat a day cut back to 70 grams, which is the current U.K. average. America’s most recent guidelines did not go so far, recommending no upper limit but advising consumers to stick to lean meats only. To House Agriculture Committee chair Mike Conaway, a Texas Republican, even that’s too much.

Conaway calls the IARC report “a biased selection of studies performed by an organization notorious for distorting and misconstruing data. It is disappointing,” he added, “that the tax dollars of hardworking Americans are being used to support the activist agenda of this international agency.”

Senator Pat Roberts, a Kansas Republican, who is Conaway’s counterpart on the Senate’s Agriculture Committee, takes a more tolerant view. Citing the acknowledged nutritional value in red meat, he said, “When it comes to health and living a long life, the old adage ‘everything in moderation’ holds fast.”

The final call will belong to the USDA. Any guidance the department offers will require balancing evolving science against consumer tastes and a significant share of the U.S. economy.

Nobody pretends the American omnivore is a species in imminent decline. Like it or not, somewhere deep in even the most devoted vegan are the genes that crave meat. “There’s no question that Homo sapiens adapted to eat both meat and plants,” says Katz.

What’s more, if it’s true that an army travels on its stomach, it’s true too that a nation defines itself the same way. There is a reason that when we think about Italy or Japan or Russia or Mexico we think of certain kinds of foods–and that’s the case with the U.S too.

Yes, Americans will be healthier if we eat significantly less of all meats than we do. But no less than in our real DNA, the sights and scents and rituals of meat eating are in our cultural DNA. With moderation and smarts, we may be able to honor that legacy and at the same time honor our health.

Write to Jeffrey Kluger at jeffrey.kluger@time.com.

This appears in the November 09, 2015 issue of TIME.

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