By Rita Jane Gabbett on meatingplace.com 10/26/2015
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 (a highly criticized conclusion – make sure you read to the end of this blog).
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:
• 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 shift work (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 between 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 What does “Probably Cause Cancer” actually mean? (https://www.youtube.com/watch?v=CbBkB81ySxQ)
Parsing the IARC ruling on meat and cancer; it’s complicated
By Rita Jane Gabbett on meatingplace.com 10/26/2015
The World Health Organization’s International Agency for Research on Cancer (IARC) conclusion that processed meat is a carcinogen and red meat is a probable carcinogen comes with a boatload of qualifiers.
In a four-page Q&A document, the IARC makes multiple points that dilute the severity and the actual impact of their conclusions on human health risks.
Q: Processed meat was classified as carcinogenic to humans (Group 1). Tobacco smoking and asbestos are also both classified as carcinogenic to humans (Group 1). Does it mean that consumption of processed meat is as carcinogenic as tobacco smoking and asbestos?
IARC: No, processed meat has been classified in the same category as causes of cancer such as tobacco smoking and asbestos (IARC Group 1, carcinogenic to humans), but this does NOT mean that they are all equally dangerous. The IARC classifications describe the strength of the scientific evidence about an agent being a cause of cancer, rather than assessing the level of risk.
Q: How many cancer cases every year can be attributed to consumption of processed meat and red meat?
IARC: According to the most recent estimates by the Global Burden of Disease Project, an independent academic research organization, about 34,000 cancer deaths per year worldwide are attributable to diets high in processed meat. Eating red meat has not yet been established as a cause of cancer. However, if the reported associations were proven to be causal, the Global Burden of Disease Project has estimated that diets high in red meat could be responsible for 50,000 cancer deaths per year worldwide. These numbers contrast with about 1 million cancer deaths per year globally due to tobacco smoking, 600,000 per year due to alcohol consumption, and more than 200,000 per year due to air pollution.
Q: Could you quantify the risk of eating red meat and processed meat?
IARC: The consumption of processed meat was associated with small increases in the risk of cancer in the studies reviewed. In those studies, the risk generally increased with the amount of meat consumed. An analysis of data from 10 studies estimated that every 50-gram portion of processed meat eaten daily increases the risk of colorectal cancer by about 18%.
The cancer risk related to the consumption of red meat is more difficult to estimate because the evidence that red meat causes cancer is not as strong. However, if the association of red meat and colorectal cancer were proven to be causal, data from the same studies suggest that the risk of colorectal cancer could increase by 17% for every 100-gram portion of red meat eaten daily.
Q: Should I stop eating meat?
IARC: Eating meat has known health benefits. Many national health recommendations advise people to limit intake of processed meat and red meat, which are linked to increased risks of death from heart disease, diabetes and other illnesses.
Q. How much meat is safe to eat?
IARC: The risk increases with the amount of meat consumed, but the data available for evaluation did not permit a conclusion about whether a safe level exists.
Q: What makes red meat and processed meat increase the risk of cancer?
IARC: Meat consists of multiple components, such as heme iron. Meat can also contain chemicals that form during meat processing or cooking. For instance, carcinogenic chemicals that form during meat processing include N-nitroso compounds and polycyclic aromatic hydrocarbons.
Cooking of red meat or processed meat also produces heterocyclic aromatic amines as well as other chemicals including polycyclic aromatic hydrocarbons, which are also found in other foods and in air pollution. Some of these chemicals are known or suspected carcinogens, but despite this knowledge it is not yet fully understood how cancer risk is increased by red meat or processed meat.
Q: Can you compare the risk of eating red meat with the risk of eating processed meat?
IARC: Similar risks have been estimated for a typical portion, which is smaller on average for processed meat than for red meat. However, consumption of red meat has not been established as a cause of cancer.
Q: What is WHO’s health recommendation to prevent cancer risk associated with eating red meat and processed meat?
IARC: The IRAC is a research organization that evaluates the evidence available on the causes of cancer but does not make health recommendations as such. National governments and WHO are responsible for developing nutritional guidelines. This evaluation by IARC reinforces a 2002 recommendation from WHO that people who eat meat should moderate the consumption of processed meat to reduce the risk of colorectal cancer. Some other dietary guidelines also recommend limiting consumption of red meat or processed meat, but these are focused mainly on reducing the intake of fat and sodium, which are risk factors for cardiovascular disease and obesity. Individuals who are concerned about cancer could consider reducing their consumption of red meat or processed meat until updated guidelines related specifically to cancer have been developed.
The American Cancer Society also warns that IARC’s list of carcinogens needs to be considered in the appropriate context, saying: “The lists themselves say nothing about how likely it is that an agent will cause cancer. Carcinogens do not cause cancer at all times, under all circumstances. Some may only be carcinogenic if a person is exposed in a certain way (for example, swallowing it as opposed to touching it). Some may only cause cancer in people who have a certain genetic makeup. Some of these agents may lead to cancer after only a very small exposure, while others might require intense exposure over many years….Even if a substance or exposure is known or suspected to cause cancer, this does not necessarily mean that it can or should be avoided at all costs…. If you have questions…be sure to ask your doctor.”
Hazard vs. Risk
The IARC also made an important distinction between its “cancer hazard” evaluations compared to actual cancer risk.
The IARC evaluates cancer hazards but not the risks associated with exposure.
The distinction between hazard and risk is important. An agent is considered a cancer hazard if it is capable of causing cancer under some circumstances. Risk measures the probability that cancer will occur, taking into account the level of exposure to the agent.
The IARC may identify cancer hazards even when risks are very low with known patterns of use or exposure. The agency explained that identifying carcinogenic hazards is important because new uses or unforeseen exposures may lead to risks that are much higher than those currently seen.
Commentary: The science doesn’t support IARC decision
(The following is a commentary submitted by National Cattlemen’s Beef Association President Philip Ellis. The views and opinions expressed are strictly those of the author.)
By Philip Ellis, NCBA President
We learned this week that the International Agency for Research on Cancer (IARC) has voted to tell the world that they believe processed meats are a human carcinogen. Similarly, they have decided red meat is a “probable carcinogen.” Let me be clear, this group did not conduct new research during their meeting, they simply reviewed existing evidence, including six studies submitted by the beef checkoff. That evidence had already been reviewed and weighed by the medical and scientific community. The science reviewed by IARC simply does not support their decision.
We know that there isn’t clear evidence to support IARC’s decision because the beef checkoff has commissioned independent studies on the topic for a decade. In fact, countless studies have been conducted by cancer and medical experts and they have all determined the same thing: No one food can cause or cure cancer. But that hasn’t prevented IARC from deciding otherwise.
Since IARC began meeting in 1979, these experts have reviewed more than 900 compounds, products and factors for possible correlation with cancer. To date, only one product (caprolactam, which is a chemical primarily used to create synthetic fibers like nylon) has been granted a rating of 4, which indicates it is “probably not carcinogenic to humans.” Most other factors or products that have been examined by the body, including glyphosate, aloe vera, nightshift work and sunlight have fallen into three categories: 2B “possibly carcinogenic to humans,” 2A “probably carcinogenic to humans,” or 1 “carcinogenic to humans.”
It seemed likely from the beginning that we’d find ourselves here. We knew the deck was stacked against us, but for nearly 100 years, the beef industry has supported nutrition research to advance the understanding of beef’s role in a balanced and healthful diet, as part of our commitment to providing a wholesome, nutritious food to Americans. We abide by a Nutrition Statement of Principles which guides our actions and communications about beef in regards to nutrition and health. We have long been working on providing credible research that is consistent with what many others outside our industry have already verified: A full, fair and unbiased examination of the entire body of research does not support a finding that red or processed meats cause cancer. This conclusion isn’t mine alone and you can evaluate the information for yourself. We’ve posted the studies reviewed by IARC and other information about the committee’s findings on the website: factsaboutbeef.com. At NCBA, our team of experts has also been working with our state partners and other industry organizations to ensure consumers understand what the science really shows.
As just one example of the work we’ve done, we commissioned a study with the same body of research reviewed by IARC. Our study engaged a panel of 22 epidemiologists from the United States and abroad who were recruited by a third-party research group. Participants in the study averaged 22 years of experience and the full panel had a combined total of 475 years of experience.
They were provided with a meta-analysis graph which showed data for a specific exposure and a specific human disease outcome, but the specific human disease outcome (colorectal cancer) and exposure (red meat) were not revealed. In other words, they plotted the results of the study findings on a graph, without telling the participants what product the studies examined.
Of the 22 participants in the study, 21 (or 95 percent) said their assessment of the magnitude of the association was weak. Of the 22 epidemiologists, only 10 (or 45 percent) said there was even a possible association. Perhaps most importantly, the epidemiologists agreed that, given the evidence provided, there is not sufficient evidence to make public health recommendations.
Cancer is a complex subject and no one understands fully what causes it or how it can be prevented. Despite billions of dollars spent on research, we only know that no one food can cause or prevent cancer.
We also know, thanks in part to decades of producer-funded work on the subject, that when people lead overall healthy lifestyles and maintain a healthy weight, they reduce their risks for chronic diseases, such as cancer.
Our team and state partners are hard at work on this topic to be certain that consumers and their influencers know and understand beef’s role in a healthy diet, regardless of what IARC might say.