It’s a bad day for meat lovers. The World Health Organization says that red meat is carcinogenic. It’ll most likely give you colorectal cancer, but pancreatic cancer and prostate cancer are also good possibilities. And that’s not even the worst of it.
According to the WHO report, eating just a couple ounces (50 grams) of processed meats per day–bacon, hot dogs, ham, jerky–will increase your chances of cancer by 18%.
The meta study was carried out by the International Agency for Research on Cancer (IARC), and assessed the results of 800 studies that investigated the link between cancer and red meat. These studies came from “many countries, from several continents, with diverse ethnicities and diets.” The working group responsible for the study concluded that “there is sufficient evidence in human beings for the carcinogenicity of the consumption of processed meat.”
Evidence of cancer risk from non-processed red meat wasn’t so certain because “no clear association was seen in several of the high quality studies and residual confounding from other diet and lifestyle risk is difficult to exclude.” The working group says, then, that there is only “limited evidence” of red meat causing cancer.
As a result, your favorite processed meat products are classed as “Group 1, carcinogenic to humans.” Group 1 also contains cigarettes and asbestos, although, as the IARC is keen to point out, “This does NOT mean that they are all equally dangerous.”
So why is cured or cooked meat so hazardous? It’s the cooking and curing itself that’s the problem. When you grill a steak, it browns and then burns. That delicious char is home to suspected carcinogens like heterocyclic aromatic amines (HAA) and polycyclic aromatic hydrocarbons (PAH). Curing meat is even worse. We sprinkle pork with nitrates and nitrites to help preserve it, or we smoke meat for both preservation and flavor. These processes both add N-nitroso-compounds (NOC) and (PAH) to the meat. You can probably guess: both of those are carcinogens.
A 2013 study published in BMC Medicine also found that processed meats kill. “The results of our analysis support a moderate positive association between processed meat consumption and mortality, in particular due to cardiovascular diseases, but also to cancer,” says the report. It recommends eating less than 20 grams (0.7 ounces) or less of processed meat per day to reduce the risk of death.
Whichever way you slice it, it seems that meat will kill you, whether it clogs up your heart or gives you bowel cancer. The meat industry, however, doesn’t agree. The North American Meat Institute (NAMI) says that the IARC “defies common sense,” and ignores “dozens of studies showing no correlation between meat and cancer.”
“Followers of the Mediterranean diet eat double the recommended amount of processed meats,” said NAMI president and CEO Barry Carpenter. “People in countries where the Mediterranean diet is followed, like Spain, Italy and France, have some of the longest lifespans in the world and excellent health.”
Looking past the bluster in this press release, we see that those “dozens” of studies are actually two studies. One of these is mostly irrelevant, and actually concludes that “animal foods tended to be associated with an increased risk in females.” The other investigated nitrates and nitrites in the diet, and comes to an interesting conclusion. It found no evidence that nitrites cause cancer, but only if it is not “co-administered” (taken together with) a “carcinogenic nitrosamine precursor.”
What are carcinogenic nitrosamine precursors? They come from nitrites, and are formed “under certain conditions, including strongly acidic conditions. One place that has strongly acidic conditions: the human stomach. High temperatures, as in frying, can also enhance the formation of nitrosamines.” That is, cooking or digesting meat can bring about the conditions that make it carcinogenic, which seems to be pretty much what IARC said.
This isn’t the first time that the NAMI has attacked the science and tried to mislead, but the effort is still fun to watch. “Only one substance, a chemical in yoga pants, has been declared by IARC not to cause cancer,” said Carpenter in the NAMI press release.
So do we have to stop eating bacon? No, but like anything, we shouldn’t eat too much. The IARC recommends 20 grams or less per day, and that you shouldn’t eat it every day anyway. And while it might also seem smart to avoid pan-frying or grilling your meat in favor of slower cooking methods like stewing, the WHO won’t commit to recommendations for cooking methods. “There were not enough data for the IARC Working Group to reach a conclusion about whether the way meat is cooked affects the risk of cancer,” says the report’s Q&A.
This new report may accelerate the current decline of meat consumption, but new vegetarian recruits probably won’t stay away for long. Research shows that 84% of vegetarians and vegans go back to eating meat in the end, because meat is just too delicious.
The answer, then, is moderation. The odd BLT or slice of ham probably won’t kill you, but don’t eat it every day, and buy better-sourced meat when you do.
“Because meat products can be some of the most resource intensive to produce,” says Dave Wallinga of the Natural Resources Defense Council, “eating less–and more sustainably raised–meat can reduce the impact of the conventional meat industry on our land, water, air and climate.”