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Red Meat Tied to Cancer, Study Finds

Eating bacon, hot dogs and other processed meats increases the risk of cancer, while red meat may pose a similar threat, according to a report Monday by the World Health Organization that drew swift criticism from meat-industry groups. The conclusion, published in a medical journal by a panel of researchers for the WHO’s International Agency for Research on Cancer, classifies processed meats as carcinogenic to people, its strongest risk category for cancer and one that includes tobacco smoke and diesel-engine exhaust.

Red and processed meats have the potential to cause cancer in humans, according to a report by a World Health Organization agency.

The agency said red meats such as steaks or pork chops probably contribute to cancer too, placing them in a lower risk caegory alongside glyphosate, a widely used herbicide.

A group of 22 scientists for the Lyons, France-based agency, considered an authority in evaluating evidence on cancer causation, assessed more than 800 studies on meat and cancer, concluding there is evidence to support a link between eating too much meat and the onset of colon, stomach and other cancers. Meat-industry groups on Monday said the scientific evidence for the group’s conclusions is inadequate.

The report confirms the previous recommendations of expert committees. The World Cancer Research Fund in 2011 concluded there is strong evidence that both red and processed meat increase the risk of colorectal cancer, advising that people eat no more than 500 grams, or about 1.1 pounds, a week of meats like beef, pork and lamb. That is the equivalent of three or four small meat patties.

The WHO agency’s report doesn’t specify a threshold for the amount of meat considered safe to eat, but rather states that consuming more increases the cancer risk. The WHO agency based the processed-meat conclusion on evidence linking meat consumption with colorectal and stomach cancer. The red meat classification took into account the positive associations with colorectal, pancreatic and prostate cancer, according to the report.

The researchers defined processed meat as products that have been salted, cured, smoked, or otherwise changed to enhance flavor or preservation, like chicken sausages and ham. Processing meats can produce carcinogenic chemicals from preservatives including nitrates and nitrites, according to the WHO agency. Some companies make products marketed as free

The agency put red meat in a lowerrisk category than processed meat.

from added nitrites or nitrates, but scientists emphasized that there are other potential cancer-causing mechanisms in such foods, and there is little research specifically focused on meats touting such claims. The bulk of the studies reviewed on processed meat didn’t distinguish between red meat and poultry products, so the findings cover all products that fit the definition, said Dr. Mariana Stern, an associate professor of preventative medicine at the University of Southern California and one of the authors of the report. The committee weighed most heavily research that studied the general population and followed people over time. It cited studies suggesting that even small amounts on a daily basis are associated with an increased risk of certain types of cancer. For instance, in one analysis of a group of 10 studies, there was a 17% increase in the risk of colorectal cancer for every 100 grams per day of red meat consumed and an 18% increase for every 50 grams daily of processed meat. However, the data in general weren’t as clear-cut for red meat as for processed meat, according to the committee. “No clear association was seen in several of the high-quality studies” and it was difficult to separate diet from other lifestyle factors that might also be linked to cancer, like smoking or exercise, the authors wrote. “The link to cancer is supported by increasingly compelling research,” said Marion Nestle, a professor of nutrition at New York University who wasn’t involved in the report. “There seem to be many reasons to eat less beef, climate change among them, but cancer is a more

personal worry.” The mechanisms for why red meat may contribute to the onset of cancer aren’t well understood, some scientists not involved in the report said Monday.

In its report, the committee pointed to several stud- ies that linked eating red meat with changes in oxidative- stress markers, suggesting an imbalance between free radicals and the body’s ability to repair the damage, and formation of N-nitroso compounds, which have been linked to various forms of cancer. Cooking meat at high temperatures, such as panfrying, also may play a role because it releases high amounts of chemicals linked to cancer.

The U.S. meat industry lambasted the report. The conclusions “defy both common sense and dozens of studies showing no correlation between meat and cancer and other studies showing the many health benefits of balanced diets that include meat,” said the North American Meat Institute, a Washington, D.C., group that represents and lobbies for meat and poultry producers like Tyson Foods Inc. and JBS USA, a division a Brazilian meatpacker JBS SA.

The meat institute, bracing for the report, on Friday launched a seven-video series of statements on the agency’s conclusions, reiterating its view that the committee relied on limited data.

The meat industry has battled international and U.S. health authorities on the place of meat in a balanced diet for decades, most recently in the U.S. Department of Agriculture and Health and Human Service’s Dietary Guidelines for Americans, which serve as a benchmark for the agencies’ nutrition education and food-assistance programs.

“The bulk of evidence really hinged around observational studies,” said Shalene McNeill, director of human nutrition at the National Cattlemen’s Beef Association, which she says had a “limited ability to disentangle the other factors that could be contributing to an outcome” including exercise, smoking or other components of a subject’s lifestyle.

Nutritionists said the report doesn’t mean that people should eliminate red or processed meats altogether, but rather they should eat them in moderation. Red meat is a good source of iron, zinc and the vitamin B-12, and many people world-wide suffer from iron and zinc deficiency, said Tom Sanders, professor emeritus of nutrition and dietetics at King’s College London. It isn’t necessary to eat large amounts of meat in order to get the necessary nutrients, he cautioned.