Source: Rita Jane Gabbett, MEATINGPLACE, 10/28/15
The International Agency for Research on Cancer (IARC), the cancer agency of the World Health Organization, has concluded that processed meat is carcinogenic to humans and that red meat is probably carcinogenic to humans.
After thoroughly reviewing the accumulated scientific literature, a Working Group of 22 experts from 10 countries convened by the IARC Monographs Programme classified the consumption of red meat as probably carcinogenic to humans (Group 2A), based on limited evidence that the consumption of red meat causes cancer in humans and strong mechanistic evidence supporting a carcinogenic effect.
This association was observed mainly for colorectal cancer, but associations were also seen for pancreatic cancer and prostate cancer.
Processed meat was classified as carcinogenic to humans (Group 1), based on sufficient evidence in humans that the consumption of processed meat causes colorectal cancer.
THe IARC defined red meat as referring to all types of mammalian muscle meat, such as beef, veal, pork, lamb, mutton, horse, and goat.
Processed meat refers to meat that has been transformed through salting, curing, fermentation, smoking, or other processes to enhance flavor or improve preservation. Most processed meats contain pork or beef, but processed meats may also contain other red meats, poultry, offal, or meat by-products such as blood. Examples of processed meat include hot dogs (frankfurters), ham, sausages, corned beef, and biltong or beef jerky as well as canned meat and meat-based preparations and sauces.
“For an individual, the risk of developing colorectal cancer because of their consumption of processed meat remains small, but this risk increases with the amount of meat consumed,” says Dr. Kurt Straif, head of the IARC Monographs Programme. “In view of the large number of people who consume processed meat, the global impact on cancer incidence is of public health importance.”
The IARC concluded that each 50 gram portion of processed meat eaten daily increases the risk of colorectal cancer by 18 percent.
”These findings further support current public health recommendations to limit intake of meat,” says Dr. Christopher Wild, Director of IARC. “At the same time, red meat has nutritional value. Therefore, these results are important in enabling governments and international regulatory agencies to conduct risk assessments, in order to balance the risks and benefits of eating red meat and processed meat and to provide the best possible dietary recommendations.”
The agency categorizes the cancer-causing potential of substances as such:
• Group 1: Carcinogenic to humans
• Group 2A: Probably carcinogenic to humans
• Group 2B: Possibly carcinogenic to humans
• Group 3: Unclassifiable as to carcinogenicity in humans
• Group 4: Probably not carcinogenic to humans
Meat industry responses
The North American Meat Institute (NAMI) said a vote by an International Agency for Research on Cancer (IARC) Monograph panel classifying red and processed meat as cancer “hazards” defies both common sense and numerous studies showing no correlation between meat and cancer and many more studies showing the many health benefits of balanced diets that include meat. Scientific evidence shows cancer is a complex disease not caused by single foods and that a balanced diet and healthy lifestyle choices are essential to good health.
“It was clear sitting in the IARC meeting that many of the panelists were aiming for a specific result despite old, weak, inconsistent, self-reported intake data," said Betsy Booren, NAMI Vice President of Scientific Affairs. “They tortured the data to ensure a specific outcome.”
“Red and processed meat are among 940 agents reviewed by IARC and found to pose some level of theoretical 'hazard.’ Only one substance, a chemical in yoga pants, has been declared by IARC not to cause cancer,” said Booren.
“IARC says you can enjoy your yoga class, but don’t breathe air (Class I carcinogen), sit near a sun-filled window (Class I), apply aloe vera (Class 2B) if you get a sunburn, drink wine or coffee (Class I and Class 2B), or eat grilled food (Class 2A). And if you are a hairdresser or do shiftwork (both Class 2A), you should seek a new career,” she added.
IARC’s panel was given the basic task of looking at hazards that meat could pose at some level, under some circumstance, but was not asked to consider any off-setting benefits, like the nutrition that meat delivers or the implications of drastically reducing or removing meat from the diet altogether.
“Followers of the Mediterranean diet eat double the recommended amount of processed meats. 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,” said Booren.
“IARC’s decision simply cannot be applied to people’s health because it considers just one piece of the health puzzle: theoretical hazards. Risks and benefits must be considered together before telling people what to eat, drink, drive, breathe, or where to work,” she said.
"The research IARC Monograph considers does not prove causes and effects. IARC Monograph panels only review research completed by others and try to make conclusions about theoretical hazards. They also determine what research to consider and what research to disregard. In the review of red and processed meat, many reputable studies were not considered by the panel," NAMI wrote in Q&A discussion of the IARC findings in which it also listed several studies that show no relationship betwen meat and cancer.
The IARC committee assigned to review all of the available evidence on red meat and cancer risk were divided on their opinion whether to label red meat a “probable” cause of cancer, according to Beef Checkoff nutrition scientist and registered dietitian Shalene McNeill, who observed the IARC process. “Cancer is a complex disease that even the best and brightest minds don’t fully understand.”
“Given the weak associations in human studies and lack of evidence in animal studies it is hard to reconcile the committee’s vote,” says nutritional toxicologist James Coughlin, in a news release issued by the National Cattlemen’s Beef Association.
Coughlin, a toxicologist with more than 40 years of experience in meat and cancer, is critical of the IARC review process due to the lack of transparency, selective inclusion or exclusion of studies and broad interpretation of study results that are inconsistent with the conclusions of the study authors.
“In my experience as an observer to an IARC working group, the process typically involves scientists who have previously published research on the substance being reviewed and may have a vested interest in defending their own research,” says Coughlin. “In the case of red and processed meat, the overall scientific evidence simply does not support their conclusion.”
To help understand how IARC’s decision-making process works, watch this YouTube video.
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