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Processed Meat and Red Meat

Source: The Guardian
Sarah Boseley Health editor

UN health body says bacon, sausages and ham among most carcinogenic substances along with cigarettes, alcohol, asbestos and arsenic.

Bacon, ham and sausages rank alongside cigarettes as a major cause of cancer, the World Health Organisation has said, placing cured and processed meats in the same category as asbestos, alcohol, arsenic and tobacco.

The report from the WHO’s International Agency for Research on Cancer said there was enough evidence to rank processed meats as group 1 carcinogens because of a causal link with bowel cancer.

It places red meat in group 2A, as “probably carcinogenic to humans”. Eating red meat is also linked to pancreatic and prostate cancer, the IARC says.

The IARC’s experts concluded that each 50-gram (1.8-ounce) portion of processed meat eaten daily increased 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,” said 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 decision from the IARC, after a year of deliberations by international scientists, will be welcomed by cancer researchers but it triggered an immediate and furious response from the industry, and the scientists it funds, who rejected any comparison between cigarettes and meat.

“What we do know is that avoiding red meat in the diet is not a protective strategy against cancer,” said Robert Pickard, a member of the Meat Advisory Panel and emeritus professor of neurobiology at Cardiff University. “The top priorities for cancer prevention remain smoking cessation, maintenance of normal body weight and avoidance of high alcohol intakes.”.

But the writing has been on the wall for ham, bacon and sausages for several years. The World Cancer Research Fund has long been advising people that processed meat is a cancer hazard. It advises eating products such as ham, bacon and salami as little as possible and having no more than 500g a week of red meat, including beef, pork and lamb.

Prof Tim Key, Cancer Research UK’s epidemiologist at the University of Oxford, said: “Cancer Research UK supports IARC’s decision that there’s strong enough evidence to classify processed meat as a cause of cancer, and red meat as a probable cause of cancer.

“We’ve known for some time about the probable link between red and processed meat and bowel cancer, which is backed by substantial evidence.

“This decision doesn’t mean you need to stop eating any red and processed meat. But if you eat lots of it you may want to think about cutting down. You could try having fish for your dinner rather than sausages, or choosing to have a bean salad for lunch over a BLT.”

The statement from the IARC, published as an article in the journal Lancet Oncology, substantially toughens the line, especially against processed meat. But while cancer scientists are concerned about the risks of eating too much meat, some nutritionists maintain that the extra risk is relatively small and that meat has other benefits.

Dr Elizabeth Lund – an independent consultant in nutritional and gastrointestinal health, and a former research leader at the Institute of Food Research, who acknowledges she did some work for the meat industry in 2010 – said red meat was linked to about three extra cases of bowel cancer per 100,000 adults in developed countries.

“A much bigger risk factor is obesity and lack of exercise,” she said. “Overall, I feel that eating meat once a day combined with plenty of fruit, vegetables and cereal fibre, plus exercise and weight control, will allow for a low risk of colorectal cancer and a more balanced diet.”

Prof Ian Johnson, emeritus fellow at the Institute of Food Research, also said the effect was small. “It is certainly very inappropriate to suggest that any adverse effect of bacon and sausages on the risk of bowel cancer is comparable to the dangers of tobacco smoke, which is loaded with known chemical carcinogens and increases the risk of lung cancer in cigarette smokers by around twentyfold.”

The North American Meat Institute said defining red meat as a cancer hazard defied common sense.

“It was clear, sitting in the IARC meeting, that many of the panellists were aiming for a specific result despite old, weak, inconsistent, self-reported intake data,” said Betsy Booren, the institute’s vice-president of scientific affairs. “They tortured the data to ensure a specific outcome.

“Red and processed meat are among 940 agents reviewed by the IARC and found to pose some level of theoretical ‘hazard’. Only one substance, a chemical in yoga pants, has been declared by the IARC not to cause cancer.

“The IARC says you can enjoy your yoga class, but don’t breathe air (class 1 carcinogen), sit near a sun-filled window (class 1), apply aloe vera (class 2B) if you get a sunburn, drink wine or coffee (class 1 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.”

WHO report says processed meat causes cancer, confusion follows

Agency weighed the evidence on carcinogens, not the risk
By Daniel Schwartz, CBC News Updated: Nov 03, 2015
Source: CBC News

Confused about processed or red meat and cancer? If so, you could blame the reporting on that big story.

Some journalists who covered a recent report by a World Health Organization agency about processed meat causing cancer and red meat probably causing cancer found that report confusing.

So it’s no surprise that, once their stories were published, more people became confused, and many wondered about the risks of eating meat.

The report, by the WHO’s International Agency for Research on Cancer, looks at the evidence about whether processed meat and red meat cause cancer.

It is not a report about risk.

Processed meat ‘carcinogenic to humans’
IARC evaluated all the evidence available and decided to classify consumption of processed meat as “carcinogenic to humans” and consumption of red meat as “probably carcinogenic to humans.” Classification is their specialty.

IARC didn’t do its own field research. It went through more than 800 epidemiological studies on cancer and red and processed meat and weighed those findings together, IARC spokeswoman Véronique Terrasse says.

While the studies were not absolute in their findings, IARC determined there is more than enough evidence to conclude eating processed meat can cause cancer.

The IARC article, which appears in The Lancet Oncology, includes a definition of processed meat but isn’t clear on what products that includes. In a Q&A document, IARC does list hot dogs, ham, sausages, corned beef and beef jerky, and says they may contain poultry. That document also says, ” The cancer risks associated with consumption of poultry and fish were not evaluated.”

However, Kurt Straif, a report co-author and the head of the IARC unit that produces their evaluations, says that in the studies they reviewed, “the processed meat may contain poultry.”

IARC doesn’t consider the weight of the evidence on red meat convincing enough yet to say that it causes cancer, only that it probably does. That includes horse meat like this steak served at Toronto’s La Palette restaurant. (Chris Young/Canadian Press)

Asked whether the IARC evaluation means processed poultry is carcinogenic to humans, Straif added that in the studies, “processed meat typically consist of beef and pork meat” but the more detailed analyses of different types of processed meats did not show conclusive differences.

Processed poultry accounts for 40 per cent of the processed meat sold worldwide.

IARC doesn’t consider the weight of the evidence on red meat convincing enough yet to say that it causes cancer, only that it probably does. In other words, more research is needed, but until then limit your consumption.

A report about evidence, not risk
For red meat and processed meat, Terrasse says, “The classification gives you an idea about the strength of evidence that it causes cancer but it doesn’t give you any clue about how much you need to be exposed to have cancer, it’s not a classification about the risk.”

IARC’s findings got major attention, not because they were a surprise, or even new. For example, since 2002, the American Cancer Society has recommended we limit our consumption of red and processed meat, Susan Gapstur, ACS vice president of epidemiology told CBC News.

She says the IARC report, “just further supports the importance of eating and consuming a healthful diet.”

In addition to cutting back on the consumption of red and processed meat, that includes “choosing healthier alternatives like poultry, fish, beans, and enriching your diet with other plant-based products,” she says.

The attention comes from the weight IARC carries in the medical community and with governments. Epidemiologist Roberta Ferrence told CBC News that IARC is highly respected, “the last word on cancer” causality. She is the senior scientific advisor at the Ontario Tobacco Research Unit and a University of Toronto professor.

Press release feeds confusion
While IARC doesn’t provided guidelines on risk, it does mention that a 2011 meta-analysis study found a 17 per cent increased risk of bowel cancer from eating 100 g of red meat per day and an 18 per cent increase from consuming 50 grams of processed meat per day.

Although that isn’t their estimate, Straif told CBC News that the IARC Working Group views that meta-analysis as “the best estimate of risk.”

However, an IARC press release incorrectly attributes the risk estimate. It says it was the IARC experts who “concluded that each 50 gram portion of processed meat eaten daily increases the risk of colorectal cancer by 18%.”

And then risk became a big part of the news reporting, and the confusion, even though IARC’s work isn’t about risk. A phrase search on Google for that quote from the press release comes back with over 5,000 results. (IARC’s principles would allow them to “undertake to estimate dose–response relationships.”)

The American Cancer Society and Cancer Research U.K., also cite that 2011 meta-analysis, so the issue is old news made new again by journalists reading that IARC press release. For the record, this is from the ACS in 2012: “Current evidence supports approximately a 15 per cent to 20 per cent increased risk of cancers of the colon and/or rectum per 100 g of red meat or 50 g of processed meat consumed per day.”

Group 1 carcinogens
IARC has been criticized for including processed meats in its Group 1 of carcinogens, because it doesn’t explain how such meats differ in risk from other Group 1 causes like tobacco, for example.

Worldwide, about 526,000 deaths from cardiovascular disease and 34,000 deaths from bowel cancer are attributable to a diet high in processed meat, the Institute for Health Metrics and Evaluation says. (CBC)

But IARC isn’t looking at the risk, it’s looking at the evidence, and saying the evidence is there for processed meats.

Ferrence, a go-to expert on tobacco, has no problem with that. “There are lots of things that are Group 1 carcinogens that are less hazardous than tobacco.

“It means they’re known carcinogens, it doesn’t say anything about the magnitude of the risk, or the magnitude of the consequences.”

And she points out that the risks of smoking and the risks of a diet high in processed meats are not limited to just one disease, so a risk assessment of just bowel cancer, the focus of the meta-analysis, won’t give someone a complete picture on which to make personal choices.

Other health issues for processed meat
Researchers most frequently associate eating red and processed meat with bowel (or colorectal) cancer, but there’s also been significant research linking processed meat to stomach cancer and red meat to pancreatic or prostate cancer, as well as limited research linking both meats to several other cancers.

Cancer isn’t the only health issue around processed meat, or even the most serious. The Institute for Health Metrics and Evaluation’s Global Burden of Disease study estimates that in 2013, the number of deaths attributable to a diet high in processed meat was 526,000 for cardiovascular disease, 84,000 for diabetes and related diseases, and 34,000 for bowel cancer. That totals 644,000 deaths worldwide.

Bowel cancer ranks as the third most-commonly diagnosed cancer in Canada (excluding non-melanoma skin cancers), according to the Canadian Cancer Society. The CCS estimates that this year, 25,100 people in Canada will be diagnosed and 9,300 Canadians will die from bowel cancer. They estimate a Canadian has a one in 15 chance of developing that cancer during their lifetime.

Besides red and processed meats, radiation, alcohol, tobacco, and obesity are also listed as risk factors for bowel cancer.

And the length of time for consumption also may matter, Ferrence points out, noting that the cancer risk doubles for every 10 years someone smokes.

Ferrence does say that, “Smoking is probably a greater risk, but smoking is a greater risk than almost anything else.”

For her, the take-away from the IARC report is that “people would be wise to reduce their intake or eliminate” processed meats from their diet. That’s something she did long ago; she didn’t wait for IARC.

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