For the first time, the International Agency for Research on Cancer included in a report on agents causing cancer the relative risk of getting the disease, a significant development, according to numerous observers at a recent meeting of the group.
The World Health Organization agency at an Oct. 6-13 meeting in Lyon, France, concluded that the relative risk of contracting cancer from consuming red or processed meat is low. It did classify processed meat as a cause of colorectal cancer and a possible cause of gastric cancer and red meat as a probable cause of colorectal cancer and a possible cause of pancreatic and prostate cancer. IARC previously has classified as carcinogens such things as sunlight, alcoholic beverages and being a barber.
“You know, my mother used to say, ‘Everything in moderation,’” says National Pork Producers Council President Ron Prestage, a veterinarian and pork producer from Camden, S.C. “She was a very smart woman, and the smart people out there know you don’t eat a pound of anything every day. So take this IARC report with a grain of salt, but not too much salt because that would be bad for you.”
The IARC classifications on meat, the NPPC says, were reached after including studies that did not have statistically significant results, meaning the conclusions are questionable. In fact, IARC’s conclusions were based on “relatively weak statistical associations from epidemiological studies that were not designed to show cause and effect.” In many of the studies, cancer risks were only associated with high levels of consumption.
In a May 2015 review of epidemiological studies on cancer and meat, David Klurfeld, with the USDA’s Agricultural Research Service, found: “Most observational studies report small, increased relative risks [of cancer]. However, there are many limitations of such studies, including inability to accurately estimate intake, lack of pre-specified hypotheses, multiple comparisons, and confounding from many factors – including body weight, fruit/vegetable intake, physical activity, smoking, and alcohol – that correlate significantly either positively or negatively with meat intake and limit the reliability of conclusions from these studies.”
IARC did note that most colorectal cancers are caused by more than one agent and that cancer trends are related to the amount of an agent or agents consumed. A monograph on the agency’s conclusions is expected to be published next summer or fall.
The NPPC, which had a representative at the IARC meeting, says many studies show that eating lean, protein-packed and nutrient-dense processed meats such as ham can help fight obesity, which is universally accepted as one of the leading causes of cancer.
According to the National Institutes of Health’s National Cancer Institute, obesity and physical inactivity may account for 25 to 30% of several major cancers, including colon cancer. The institute has noted that a 2002 “major” review of observational trials showed that physical activity reduced colon cancer risk by 50%: www.cancer.gov/about-cancer/causes-prevention/risk/obesity/obesity-fact-sheet.
U.N. agency's explanation
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, 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.
The consumption of meat varies greatly between countries, with from a few percent up to 100% of people eating red meat, depending on the country, and somewhat lower proportions eating processed meat. The experts concluded that each 50-gram portion of processed meat eaten daily increases the risk of colorectal cancer by 18%.
“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 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 Working Group considered more than 800 studies that investigated associations of more than a dozen types of cancer with the consumption of red meat or processed meat in many countries and populations with diverse diets. The most influential evidence came from large prospective cohort studies conducted over the past 20 years.
IARC Monographs Q&A on the carcinogenicity of the consumption of red meat and processed meat: www.iarc.fr/en/media-centre/iarcnews/pdf/Monographs-Q&A_Vol114.pdf
Cancer is complex, and a balanced diet is key to staying healthy
The North American Meat Institute says a vote by an International Agency for Research on Cancer 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,” says Betsy Booren, Ph.D., 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,” Booren says.
“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.”
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,” Booren says.
“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 says.
Highly questionable decision
National Pork Board Chief Executive Officer Chris Hodges said the following about the IARC classification:
“We have reviewed the International Agency for Research on Cancer report and find that the panel’s conclusions on processed and red meats are not based on evidence that proves causation and therefore are highly questionable. The primary body of evidence used by IARC is observational studies that are unable to find a cause-and-effect relationship. Complicating the relationship is that many factors are at play, including genetics, lifestyle and even how meat is prepared.
“Health professionals continue to recommend including lean meats, such as pork, in a healthy diet. Cancer risk is complex and develops over many years. Any attempt to tie specific foods and cancer risk in a cause-effect relationship would be difficult at best. In fact, the studies examined by IARC did not consistently define the types of red and processed meats, which vary greatly.
“Importantly, when included as part of a healthy, balanced diet, the benefits of meat (and pork, in particular) are significant. As a lean source of protein, pork provides nutrients not found in other protein sources. We continue to work with our 63,000 pig farmers across the U.S. and through the production, retail and food service chain to deliver high-quality, healthy pork to consumers worldwide.
“Based on all we know about the nutritional composition of pork, this classification was not expected. The Pork Checkoff, as well as our barnyard brethren, have funded numerous objective and independent scientific studies on the nutritional value of pork and other lean meats, so we feel this designation is flawed and inaccurate. This research continues to indicate that lean meat should be included as part of a healthy, balanced diet.
“As consumers of our own product, we care about the health of our own families and our consumers. Based on existing and available science, we are confident in the safety and nutritional value of the pork products available today. We and many health professionals encourage all consumers to continue to enjoy pork as a lean meat protein and as part of a healthy, balanced diet.”
Consumers are encouraged to visit www.porkcares.org/porkbenefits to learn more about the nutritional benefits of pork, to view the nutritional science and research available on pork, and to learn more about the IARC classifications.