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Health Check: does processed meat cause bowel cancer?

Each year around 14,400 Australians are diagnosed with bowel (colon and rectal) cancer. It’s the second most common newly diagnosed cancer after lung cancer and claims around 3,980 lives a year. The good…

Processed meats and large quantities of cooked red meats (more than 500g a week) increase your risk of bowel cancer. Flickr/Pabo76

Each year around 14,400 Australians are diagnosed with bowel (colon and rectal) cancer. It’s the second most common newly diagnosed cancer after lung cancer and claims around 3,980 lives a year.

The good news is that bowel cancer has a high cure rate if detected early.

And there is convincing evidence that you can reduce your risk of it by regularly eating foods that are high in dietary fibre, such as wholegrains, legumes, pulses, high fibre cereals, vegetables and fruit. In fact, for every ten grams of fibre you consume per day, your risk reduces by 10%.

Being physically active for at least 30 minutes a day also decreases your risk of bowel cancer.

But the other side of the risk equation is bad news for those who love a good deli meat: the regular consumption of processed meat increases your chances of getting bowel cancer.

What does the evidence say?

Red meat contains important nutrients such as protein, iron, zinc, vitamins B12, thiamin, riboflavin and niacin. But there is convincing evidence that eating more than 500 grams of cooked meat per week is risky.

The latest World Cancer Research Fund meta-analysis of 12 separate studies indicates that for every 100 gram increase in red meat a day there is a 17% increase in bowel cancer risk.

For processed meat, there appears to be no completely safe level of intake, with a meta-analysis of 13 studies finding an 18% increase in bowel cancer risk for every 50-gram increase in daily intake.

How much do we eat?

Ham and bacon are the most commonly consumed processed meats in Australia, with almost half (44%) of the population eating them once a week or more often. Other favourites include pastrami, salami, corned beef, chorizo, devon, fritz, luncheon meats, some sausages, hot dogs, cabanossi, kabana, and bratwursts.

The last National Nutrition Survey found that among adults who ate processed meat on the day of the survey, men and women ate around 40 grams and 26 grams respectively. For sausages, frankfurts and saveloys, this rose to 110 and 76 grams.

To reduce your risk of bowel cancer, try to save processed meats for special occasions. Flickr/baengel

Processed meat is preserved by smoking, curing, salting or the addition of preservatives including nitrite, nitrates, phosphate, glutamate or ascorbic acid.

In Australia, mince meat has no additives and so is defined as fresh meat. Minced meats or hamburger patties are only considered processed if they are chemically preserved, which means you need to check the methods used to process these products if you eat them regularly.

What components cause cancer?

Naturally occurring food components, cooking techniques and additives in red and processed meat all impact on the mechanisms that lead to development of cancer.

Nitrates and nitrites occur naturally in plant foods as part of the nitrogen cycle between air, land and water environments. These chemicals are added to cured meats to help kill bacteria and are also produced in meat during the curing process or in the stomach during digestion of meat. Both processes play a role in the production of N-nitroso compounds that contribute to cancer risk.

It’s important to note, however, that the nitrate found in vegetables accounts for the majority of dietary consumption of the chemical. Recent reviews confirm some health benefits from naturally occurring food sources and say we need to re-examine the link between nitrate and cancer.

The haem iron in meat also promotes the formation of N-nitroso compounds. When meats are cooked at high temperatures, compounds called heterocyclic amines and polycyclic aromatic hydrocarbons are produced and also increase cancer risk.

It’s not just about the meat

Other important risk factors for bowel cancer include age (especially being over 50 years), having a family or personal history of the disease, specific genetic conditions and having inflammatory bowel disease for more than eight to ten years.

Definitive steps you can take to reduce your risk of bowel cancer include knowing your family history and participating the national bowel cancer screening program, which invites Australians who turn 50, 55, 60 and 65 to be screened.

But a simple step to reduce your risk is to change the way you think about meat: keep serve sizes of cooked red meat small – 80 grams of cooked meat up to six times a week with some meat free days. And save processed meats for special occasions.

Join the conversation

90 Comments sorted by

Comments on this article are now closed.

  1. Geoff Russell

    Computer Programmer, Author

    Richard Peto did a gruesome piece of research back in 1975 which showed pretty well that age doesn't cause cancer (in mice) and this relation, wrt bowel cancer is supported in people by ecological comparisons in countries that do and don't eat red meat. In those that eat very little, there simply isn't much bowel cancer beyond those caused by known genetic predispositions. Also absent in these countries is the usual male/female rate difference. So age isn't a risk factor, its simply a proxy for a longer exposure making more risk. The 500 gram threshold chosen by WCRF isn't supported by the data they used. Their dose-response graph kicks up at one red meat meal per week, and Australian data is similar, so why pretend that 500 grams is the threshold? ... see Marion Nestle's "Food Politics", still highly relevant.

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  2. Pamela H.

    logged in via email @hotmail.com

    Not only processed meat, but all red meat causes bowel cancer. It has no vitamins or fibre, it is loaded with cholesterol, bovine growth hormones, bovine levels of antibiotics, and sometimes disease. By the way, all meat is 'processed', unless you're eating it directly from a live animal as a true carnivore does in the wild.

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    1. John Newton

      Author Journalist

      In reply to Pamela H.

      Pamela - not entirely true. If you eat organic meat or pasture fed beef, you will not be subjected to bovine somatotropine - growth hormones

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    2. Pamela H.

      logged in via email @hotmail.com

      In reply to Rosemary Stanton

      Ah Rosemary, It's been known by non-meat-eaters for years that some of your advice may not be entirely accurate yourself. Your name may be well known but many nutritionists have it wrong when it comes to meat. They tend to go by the outdated pyramid idea which has now been replaced with more updated versions. Also, some nutritionists get their information from the meat and dairy industries which has infiltrated many forms of training and advertising, from pharmaceuticals to chocolate. I'd rather take a daily B complex if I felt the need, than eat a dead animal.

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    3. Rosemary Stanton

      Nutritionist & Visiting Fellow at University of New South Wales

      In reply to Pamela H.

      Pamela

      I am usually castigated for my defence of plant foods!

      I certainly don't have a problem with people who prefer to avoid eating 'dead animals'. Indeed, I wrote Healthy Vegetarian Eating and my recipe books feature many plant-based foods.

      I do have a problem with incorrect information. Published data on the nutrients in red meat (see the NutTab data base) do not come from the meat industry. To state that meat does not contain B vitamins is simply untrue.

      As part of the Dietary Guidelines…

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  3. Citizen SG

    Citizen

    So... if you live long enough not to be killed by misadventure you may become one of the .015% of men or .009% of women who die yearly from a nasty disease.

    There are other large risk factors for colorectal cancer; including 1st degree family relatives with the disease, smoking history, amount of fibre and fresh fruit/vegetables in the diet and exercise that also contribute greatly to the development of (or resistance to) bowel cancer.

    Keep enjoying your bacon - but eat an apple afterwards and walk to the cafe.

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    1. Rosemary Stanton

      Nutritionist & Visiting Fellow at University of New South Wales

      In reply to Citizen SG

      Citizen SG

      How about some definition of 'nasty disease' and some figures on misadventure.

      It is probably more meaningful to note the actual numbers, as Clare has quoted (also available from the Cancer Council website).

      With more than 14,400 new cases of bowel cancer diagnosed in Australia/year, it surely makes sense to avoid well documented risk factors (which Clare mentioned, but which also include high body levels).

      Deaths from bowel cancer in Australia are the second highest number of cancer deaths after lung cancer.

      It's good advice to eat an apple and walk more but why not also follow the evidence-based reduce intake of red and processed meat and fill the space on the plate with plant-based foods.

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    2. Clare Collins

      Professor in Nutrition and Dietetics at University of Newcastle

      In reply to Citizen SG

      While the absolute risk is low, that [provides no comfort if teh person diagnosed with it is your dad or mum , or your brother or sister.

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    3. Citizen SG

      Citizen

      In reply to Rosemary Stanton

      HI rosemary,
      Using Clare's figures would give you a .00019% chance of dying yearly from Colorectal cancer. The age adjusted rate of death in Australia is around 15 per 100000 men (new diagnoses being 46).

      My point was that if you exercise regularly, eat plenty of fresh fruit and vegetables, have never smoked, do not take NSAIDS regularly what is your incidence of of colorectal cancer?

      If that same person ate meat, including processed meats, above the recommendations what would be the effect…

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    4. Citizen SG

      Citizen

      In reply to Clare Collins

      So red meat is the new tobacco?

      Because something is a risk does not mean that it should be avoided or omitted but placed in context within the hierarchy of Things That Are Pleasurable But May Kill You.

      The argument against red meat consumption should be tempered with the other factors that, by presence or omission, contribute to the development of colorectal disease. Without this context it is inaccurate to use population risk as a measure to apply to individual risk when ingesting a substance. Red meat is not plutonium.

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    5. Rosemary Stanton

      Nutritionist & Visiting Fellow at University of New South Wales

      In reply to Citizen SG

      Citizen SG

      Where did Clare (or I) say that red meat should be "avoided or omitted". The appropriate term is 'reduced' - in other words, don't eat too much of the stuff !

      It's obviously your choice, but those of us who work in public health try to give people some evidence-based facts to help reduce their risk of various health problems. If we just kept quiet and you later developed a health problem related to one or more risk factors, you would probably be more than a little annoyed if it had received no public mention.

      We can't do much about some risk factors (such as our choice of parents), but it makes sense to me to reduce other risks where taking action is simple - such as eating less red meat.

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    6. Geoff Russell

      Computer Programmer, Author

      In reply to Citizen SG

      Red meat is far more dangerous than plutonium. You don't eat plutonium and it's production doesn't destroy anything like the amount of wildlife habitat or produce anything like the climate damaging impacts of methane produced by cattle.

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    7. Citizen SG

      Citizen

      In reply to Rosemary Stanton

      Hi Rosemary,
      I dispute the message, not the aims of population health or the evidence.

      the full picture is the sum total of all risk factors, not just red meat or processed meat in isolation.

      The modest increase in risk if one consumes a higher amount of red meat than recommended may be subsumed by other modifiable risk factors. Whilst this makes a large difference in population health it cannot be extrapolated to an individual without recognition of the sum total of all risk factors for…

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    8. Citizen SG

      Citizen

      In reply to Geoff Russell

      kangaroo harvesting doesn't destroy habitat.

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    9. Geoff Russell

      Computer Programmer, Author

      In reply to Citizen SG

      But kangaroos provide an irrelevantly small amount of meat, and if there were enough kangaroos to provide a significant amount of meat, they'd be every bit as damaging as sheep and cattle ... probably more so because they are extremely inefficient at "growing" meat and most of their meat ends up as processed meat. Lastly, the meat is higher in heme iron, so probably even more carcinogenic.

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    10. Citizen SG

      Citizen

      In reply to Geoff Russell

      I presume that you mean the kangaroo harvest does not provide a significant amount of meat, not the beast itself.
      kangaroos are very efficient because they can range over marginal forests as well as pasture land. it's herding them and getting people to eat them that seems to be the problem.
      One could always hunt them oneself, i suppose, which might provide the exercise to offset any increased risk via increased heme iron consumption by the individual.

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    11. Rosemary Stanton

      Nutritionist & Visiting Fellow at University of New South Wales

      In reply to Citizen SG

      That's why the WCRF report includes a whole range of other factors that they have looked at. Read the report.

      Note too that the studies quoted correct for many of the confounders and still the results come up as significant.

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    12. Citizen SG

      Citizen

      In reply to Rosemary Stanton

      see my comment below in respect to the inuit. It is possible to have a diet rich in red meat and also have a low incidence of colorectal cancer. It seems that other dietary and lifestyle factors play a large part as, indeed, the WCRF report states in its first paragraph.

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    13. Sue Ieraci

      Public hospital clinician

      In reply to Citizen SG

      You are right, Citizen SG.

      It is simplistic to see any individual risk factor in isolation from all the others.

      There's nothing wrong with an article about the nature and magnitude of individual factors, but the way one runs one's life then has to be balanced and rational.

      It's easy to advise against a risk factor like smoking, which has no health benefits and well-identified harms, and affects risk for a multitude of conditions. Diet, however, is all about balance. Red meat provides protein…

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    14. Geoff Russell

      Computer Programmer, Author

      In reply to Sue Ieraci

      Sue. Your last paragraph is mistaken. You can't add and substract relative risk factors. If the RR for exercise was 0.8 and the RR for red meat was 1.2 then it doesn't follow that eating red meat and exercising would give a person a relative risk of 1.0.

      Suppose a 1000 people in a population who doesn't eat red meat and don't exercise get bowel cancer. If they all add red meat, then more will get bowel cancer. If they also all exercise, it will drop back to 1000. But we can be quite sure it…

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    15. Sue Ieraci

      Public hospital clinician

      In reply to Geoff Russell

      Goeff - you are right about the way that relative risk factors operate across a population. Perhaps I should not have said ''the ADDITIONAL'' risk.

      Non-smokers who maintain a diet high in plant foods and have no genetic pre-disposition have a low incidence of bowel cancer, whether they are vegetarian of moderate red meat eaters.

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    16. Geoff Russell

      Computer Programmer, Author

      In reply to Sue Ieraci

      WCRF doesn't list smoking as a risk factor for bowel cancer and I spent a while looking at the research back when I wrote CSIRO Perfidy. It's fascinating. Plenty of studies tried to find a link and
      failed. They just kept thinking it must be there. Eventually a couple found one between smoking and polyps ... with a 40 year lead time.
      Conversely, there's a very strong link between red meat and one
      leukemia (http://www.ncbi.nlm.nih.gov/pubmed/20042434) but most people don't pay it any attention…

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    17. Marco Dabizzi

      logged in via LinkedIn

      In reply to Sue Ieraci

      [Diet, however, is all about balance]

      How true. Food is all about balance. Too much of a nutrient can be equally unhealthier as too little, but a balanced diet doesn't satisfy the criteria of the new generation of food religions.

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  4. Rosemary Stanton

    Nutritionist & Visiting Fellow at University of New South Wales

    Clare

    Thank you for the article.

    Having tried to stay up to date on studies looking at red meat consumption and bowel cancer over many years, I query putting too much emphasis on processed meat as that can be used to detract from the very real issue of increased risk with a high intake of fresh meat.

    For example, when the definition of red/processed meat has been considered 'unclear' in some studies, that has been used as an excuse to ignore some highly pertinent information from large and relevant studies.

    Note too that pork is marketed as a 'white meat' in Australia, but the studies on meat and cancer rate it as a red meat.

    One other point concerns the connection between haem iron and the fat in meat. Haem iron can promote the peroxidation of fatty acids in red or processed meats to form cytotoxic alkenals (see http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3733138/). Note that this action of haem iron may apply to unsaturated as well saturated fatty acids.

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    1. Clare Collins

      Professor in Nutrition and Dietetics at University of Newcastle

      In reply to Rosemary Stanton

      Rosemary
      I agree with your comments. There are links to publications that detail the biological mechanisms related to cancer initiation and promotion for those seeking this detail.
      I think this issue does need greater awareness as some of the changes we can make to dietary patterns are fairly easy and painless to make, some do need more planning.

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    1. Citizen SG

      Citizen

      In reply to Richard Hockey

      yes.. 30% increase of a very low risk is still a very low risk.

      i think another analogy is:

      The chance of death in a motor vehicle accident is 6/100000 per year. You ought to drive less.

      Motor vehicle deaths are heavily skewed by drunk 20 year old males on saturday nights. So if you're a 50 year old lady driver who just drives 10 km to the shops twice a week in a country town 'driving less' is going to decrease your risk of a lethal acccident from infinitesmal to 50% of infinitesmal

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  5. Account Deleted

    logged in via email @drdrb.net

    I've seen several reports that anaemia is on the rise in many populations, particularly women and the elderly. Is less than 500 grams of red meat a week enough to supply dietary iron needs? Also, does it satisfy the dietary craving for protein that produces the "full" feeling? (basis of the CSIRO Total Wellbeing and other high-protein diets)?

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    1. Rosemary Stanton

      Nutritionist & Visiting Fellow at University of New South Wales

      In reply to Account Deleted

      James

      Many foods provide iron and you can have a perfectly adequate diet without meat, if that is your choice.

      With iron-deficiency anaemia, you need to look at other relevant factors. In most parts of the world where anaemia is common, the major problem is poverty and insufficient food, especially for women. Repeated pregnancies make the problem worse.

      For women in any part of the world, menstrual blood loss is highly relevant. Heavy periods can exceed the body's ability to increase its…

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    2. Geoff Russell

      Computer Programmer, Author

      In reply to Rosemary Stanton

      N.B. James. What Rosemary says is quite correct .. in their published studies CSIRO found NO differences in weight loss between the study group (high red meat) and the control diet.

      http://www.ncbi.nlm.nih.gov/pubmed/15941879

      But that wasn't what the authors wrote in their best seller. What they told people the research found wasn't actually what it found. And by the time of that best seller, CSIRO also knew that people didn't stick with the diet.

      So almost 10 years on and over a million books sold, the "scientifically proven" diet has failed.

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  6. Debra Taylor

    logged in via email @mac.com

    These findings are based on epidemiological data. No valid scientific conclusions can be drawn from such data without further experimentation. That is not the scientific method. Most epidemiological studies show bias otherwise the studies would not have been instigated. They all have confounding factors most of which are unknown. If red meat was so bad for us I don't think Homo sapiens would ever have established itself as a successful species.

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    1. Geoff Russell

      Computer Programmer, Author

      In reply to Debra Taylor

      Debra ... If you google "wcrf expert report" and read the report you'll find links to a raft of "further experimentation" at all levels.

      One reason humans have been successful is their ability to thrive (in the short term anyway) on an incredible range of diets and to delay the onset of things like cancer until after the main breeding age range. We don't need to live past about 25 years of age to be a very successful species ... but most of us would be happier to live considerably longer.

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    2. Citizen SG

      Citizen

      In reply to Geoff Russell

      The confounders that Debra may be writing about in the epidimiological data pertains to the non-filtering of variables. For example, those that eat the most red/processed meat might also be the ones that do the least exercise, drink the most alcohol, are smokers etc - is the risk purely that from red meat?
      Perhaps those who eat most red meat eat less fresh fruit etc...

      The conceit of this, when applied to individuals, is that it assumes an either/or circumstance for the individual. An athlete who eats processed meat may be at less risk of colorectal cancer than a vegetarian smoker who does no exercise.

      i am not red-meat denier. I know the causative mechanisms and do not dispute them. What I dispute is the application of epidimiological data to an individual that flies in the face of client contextualised care and individual risk appreciation.

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    3. Citizen SG

      Citizen

      In reply to Pamela H.

      and they're right. There is no safe threshold for cigarette smoking and cancer (although there appears to be for cardiovascular disease).
      However quantity makes the poisoon so there is a point below which smoking is much less risky to health.

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    4. Citizen SG

      Citizen

      In reply to Rosemary Stanton

      Yes,
      But, again, my point is that the WCRF report also states that exercise, fibre and other lifestyle and dietary factors are protective against colorectal cancer. The point being that any mention of red meat/processed meat needs to take these other factors into account and a prescription of '100 g of meat' is meaningless unless it is followed with + 30 minutes of exercise, 5 serves of nonstarchy fvegetables etc. etc.
      If an individual is not exercising, not eating fibre etc. it could be that…

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    5. Rosemary Stanton

      Nutritionist & Visiting Fellow at University of New South Wales

      In reply to Citizen SG

      Take a look at the lifespan of the Inuit - in the past as well as the present. I realise longevity is difficult in such a harsh environment, but the incidence of colorectal cancer increases with age.

      The Inuit diet was very rich in fish and other seafood, not beef, lamb and pork that are the major meats checked in the studies in the WCRF report.

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    6. Citizen SG

      Citizen

      In reply to Rosemary Stanton

      20% of the inuit lived past 60, although infant and young adult mortality certainly brought down their average life expectancy. In this cohort of older person cancer rates were very low.

      The inuit diet was rich in both red meat and fish. That is my point - it appears that there is something in the inuit diet and lifestyle that protecting them from colorectal cancer. Here's an account of an inuit woman describing the traditional diet:

      “Our meat was seal and walrus, marine mammals that live…

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    7. Citizen SG

      Citizen

      In reply to Citizen SG

      My point being is that it i snot heme iron alone that causes colorectal cancer - other lifestyle and dietary factors play a very large part; as the WCRF report mentions in it's first paragraph.

      Which is why every dietary prescription should not be from epidimiology but be client centred.

      if you're a regular exerciser, who consumes milk, oily fish, doesn't smoke, doesn't drink and has 'good' genes - why not do as the inuit did and eat more than 100g of red meat per serve?

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    8. Rosemary Stanton

      Nutritionist & Visiting Fellow at University of New South Wales

      In reply to Citizen SG

      Some references would be useful.
      Life expectancy at birth for Inuit of the former Northwest Territories rose from 29 years in 1941-1950 (38 years less than for Canada overall), to 37 years in 1951-1960 (33 years less), to 51 years in 1963-1966 (21 years less), and to 66 years in 1978-1982 (19 years less). For Inuit in Nunavik, life expectancy in 1984-1988 was 14 years less than for the total population of Quebec.
      By 1991, life expectancy was 68 years (from Health Reports http://www.statcan.gc.ca/pub/82-003-x/2008001/article/10463-eng.pdf).

      We don't need to go into the many causes of low life expectancy in the Inuit, but it's difficult to argue against their short life expectancy being a factor in their low incidence of colorectal cancer.

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    9. Citizen SG

      Citizen

      In reply to Rosemary Stanton

      Rosemary,
      I take it your familiar with the concept of life expectancy being an average anbd that an average life expectancy of 29 years does not mean that everyone dies at 29. A high infant mortality rate will always lower average life expectancy. Are you seriously suggesting that no inuit survived past the age of 50?
      The data comes from: Stefannson's Cancer: Disease of civilization H
      See also: Cancer patterns in Inuit populations falseFriborg, Jeppe T; Melbye, Mads. Lancet Oncology9.9 (Sep…

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    10. Citizen SG

      Citizen

      In reply to Geoff Russell

      That paper is irrelevant as it pertains to cardiovascular disease in populations now. The argument is about colorectal disease pre and post modern lifestyle changes in the inuit.

      Inuit health is, unfortunately, now very similar to those of other indiginous populations - including our own.

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    11. Citizen SG

      Citizen

      In reply to Geoff Russell

      Oh, I read it.

      It bears no relation to the central argument in the above article, or in my discussion with you and rosemary, about colorectal cancer in the inuit or the protective effects of other dietary components, as well as exercise, to mitigate against the development of cancer from heme iron consumption.

      Did you read the article? Can you explain how it directly relates to colorectal cancer development?.

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    12. Rosemary Stanton

      Nutritionist & Visiting Fellow at University of New South Wales

      In reply to Citizen SG

      Citizen - Yes, I'm familiar with what life expectancy means. Did you perhaps not note however, the changing life expectancy? And before you reply that life expectancy has also increased for other populations - yes, I do know that too. However, life expectancy was and remains lower for the Inuit than Canadians.

      There is no lack of evidence that the Inuit diet has changed and is now a poor diet dominated by processed foods. Their major dietary sources of protein have also changed dramatically with…

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    13. Geoff Russell

      Computer Programmer, Author

      In reply to Citizen SG

      I never said it had anything to do with CRC, but does tackle the general principle of people extolling the virtues of some or other traditional lifestyle without adequate evidence. And it goes back as far as there is reasonable evidence. But people love to talk about the health status of people back in the good old days before there was evidence.

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    14. Citizen SG

      Citizen

      In reply to Rosemary Stanton

      I don't disagree - more red meat in the diet causes more bowel cancer.

      My point is, and always has been, that to apply a prescripted amount of red meat, or indeed processed meat, in the diet is fanciful without recognition of strong lifestyle co-factors.

      The textbook in my office 'cancer epidimiology and prevention' suggests that constant exercise reduces the incidence of colorectal cancer by 50% - OK it's an old reference - (although the WCRF does not quote or suggest a figure). The WCRF…

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    15. Citizen SG

      Citizen

      In reply to Geoff Russell

      You appear to assume that I am some kind of paleo enthusiast. I have never 'extolled the virtues' of traditional lifestyles'. Your commentary on IHD in the inuit is entirely misdirected.

      My point was that the incidence of colrectal cancer in the inuit appears to be low. There were sufficient elderly inuit around at the turn of the last century to make that observation. In the 1950s the rate of colorectal cancer in the inuit was less than the canadian population despite a high red meat diet that is featured in the traditional inuit diet. The incidence of colorectal cancer increased threefold from the late 80's. Why?

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  7. Gary Cassidy

    Thanks for a good article.
    The advice to 'Limit red meat and save processed meats for special occasions' to reduce our risk of bowel cancer seems pretty straight forward. However, I have noted a couple of difficulties:
    - What should people replace the red/processed meat with? Without clear and relevant guidelines the replacement food may cause more harms.
    - The latest Australian Dietary Guidelines has a confusing message regarding meat. Under guideline 2 (enjoy a wide variety of nutritious foods from these five food groups every day) it is listed first in the 'protein group' (before poultry, fish, eggs, tofu, nuts and seeds, and legumes/beans). Also under the "Most Australians need more" section it is listed first in the 'protein group', although a caveat is provided for men.

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    1. Clare Collins

      Professor in Nutrition and Dietetics at University of Newcastle

      In reply to Gary Cassidy

      Gary
      thanks for your comment. ry these tips:

      1. If you like a cooked breakfast then swap bacon for a egg based breakfast and have wholegrain/wholemeal toast. Add a side of grilled tomatoes, mushrooms or spinach. (Dont forget to have a high fibre breakfast cereal most days)
      2. Avoid processed meat. Make it the exception or when there are no other choices available. On sandwiches try fresh cooked chicken, reduced fat cheese, canned tuna or salmon, baked bean or 4-bean mix .
      3. Aim for no more…

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  8. Margo Saunders

    Public Health Policy Researcher

    Thank you, Clare. I have been researching this very issue for the past few months, but you got there first!

    The links between processed meat and increased risks of cancer and cardiovascular disease were highlighted in two articles published in the online journal BMC Medicine earlier this year (http://www.biomedcentral.com/1741-7015/11/63 and http://www.biomedcentral.com/1741-7015/11/136). The articles discuss the findings of a major study which received considerable attention overseas but minimal…

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    1. Citizen SG

      Citizen

      In reply to Margo Saunders

      These are interesting articles. The EPIC study shows no association (or at least not a significant one) between red meat consumption and mortality - unless you eat no, or very little red meat, which correlates with increased mortality.

      An interesting skewing was that those who ate the most red meat were most likely to be smokers and ate the least fruit and vegetables, so a confounder is the realtive intake of fibre/fresh vegetables. Those that ate more processed meats were more likely to be physically inactive and less educated which also is an interesting confounder.

      The putative casutive factors with higher mortality were not just increased cancer but Coronary Heart Disease (not a factor with red meat) so it's not just nitrates but salt and saturated fat that seems to be the culprit here.

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    2. Geoff Russell

      Computer Programmer, Author

      In reply to Citizen SG

      You point out that the association wasn't "statistically significant" for red meat but neglect to point this out for the "no, or very little red meat" case. The big confounding factor that most European/US/Aust studies can't/don't deal with is that most people in the low or no meat
      categories didn't grow up that way. If you look at Japan, the bowel cancer wave (a 500% increase over normal (ie., low/no red meat rates)) was displaced from the rise in red meat consumption by about 20-25 years. ie., the bowel cancer a person gets at 50 is probably the result of what they were eating at 30. So for people who reduce red meat intake at 40, it may be too late. They show up in studies as low red meat, then they get cancer and confound the results.

      Here's the picture from Japan, but it's happening across Asia:
      http://www.ncbi.nlm.nih.gov/pubmed/17059355
      In Japan we are talking about 80,000 additional bowel cancers every year.

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    3. Citizen SG

      Citizen

      In reply to Geoff Russell

      and all of those are attributable to meat? I think you'll find that the causes of colorectal cancer are so varied that meat consumption is among many co-factors. Attributing 80, 000 bowel cancers to the addition of more red meat (alone) in asian diets is poor logic and most likely wrong.

      There is an ideological bent to these arguments that attribute cardiovascular disease and cancer solely to red meat consumnption.

      and by the way an extra 80000 bowel cancer diagnoses is .0006% of the population.

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    4. Citizen SG

      Citizen

      In reply to Citizen SG

      correction: calculator failure: .06% of the population.

      In fact there are 49, 000 diagnosed cases in japan yearly (as of 2008); not 80, 000.

      The age standardised rate per 100000 is 41.... .04%

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    5. Geoff Russell

      Computer Programmer, Author

      In reply to Citizen SG

      Have you got an allergy to giving references? I gave you a
      Japanese reference for my number ... and here's a second one

      http://globocan.iarc.fr

      Look at Japan 2008 ... 101656 new cases of colorectal cancer.

      In the Japanese reference you will see that they used to get about
      20,000 cases, that's an increase of over 80,000 every single year with a modest population growth. Given they have a low obesity rate the only two accepted risk factors that apply are red and processed meat and possibly inactivity.

      Going from 20,000 to 101,000 is a 500% increase ... surviving an atomic blast gave most survivors a 200 mSv radiation dose and just a 10% increase in solid cancers ... here's the reference

      http://www.rerf.jp/radefx/late_e/cancrisk.html

      Did you notice the pattern? Make a claim and then say where you got it from. Claim+Reference. That's how it works.

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    6. Citizen SG

      Citizen

      In reply to Geoff Russell

      I have an allergy to hyperbole and claims of causation from correlation.

      There is a causative factor for heme iron to cause colorecatal cancer development. there is also a protective effect from many other lifestyle factors. It is a combination of both of these (increse in consumption vs decrease in protective factors) which leads to the development of higher colorectal cancer rates in populations: see the WCRF report in the main article.

      High red meat consumption did not cause excessively high rates of colorectal cancer in the Inuit. it is not red meat alone that causes the development of colorectal cancer. That is an argument from ideology not science.

      And, yes you''re right about the japanes data - I inadvertently quoted the statistics for men only. I was right about the age standardised incidence....

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    7. John Doyle
      John Doyle is a Friend of The Conversation.

      architect

      In reply to Geoff Russell

      Have you been to Japan lately?
      Have you seen the ubiquitous vending machines on every corner, every station, every shop, selling sugary soft drinks? Have you noticed the little fatties that so many children there have become?
      Japan has unfortunately come under the spell of the West's giant food companies and begun to eat unhealthy foods that are giving rise to the epidemic of "western" lifestyle diseases. China is also not taking notice of this issue. I hope someone is pointing that out to them…

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    8. Geoff Russell

      Computer Programmer, Author

      In reply to John Doyle

      God spare me from people who think they can measure obesity rates by visiting a country ... Japan has second lowest in the world as of 2012 ... http://www.oecd.org/health/49716427.pdf

      Grass fed meat? Meat is 8 percent of global calories and pure grazing produces about 8 percent of that 8 percent ... See Livestock's Long Shadow. 8% of 8%? Irrelevant. I'd much rather leave the land to wildlife ... much of it was originally deforested, so that part can be reforested to draw down carbon.

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    9. John Doyle
      John Doyle is a Friend of The Conversation.

      architect

      In reply to Geoff Russell

      That's Better! It's even closer to your argument's validity.
      According to George Monbiot, farmland in Europe is already returning to woodland as we produce enough food already [distribution is another matter]
      According to him putting back top predators saves the environment [wolves in Yellowstone]
      And Allan Savory says we can save the pasture/grassland by using grazing animals in a certain way.
      It's most certainly not irrelevant.

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    10. Geoff Russell

      Computer Programmer, Author

      In reply to John Doyle

      Savory and Monbiot are on opposite sides here and while I'm far from making up my mind about Monbiot's arguments, Savory's "argument by photograph" hasn't withstood scrutiny ... http://bit.ly/16Yklpn

      When you use objective methods to look at entire properties instead of cherry picking the good bits, then Savory's methods are no better than other methods ... i.e, they work until you measure them properly

      http://www.sciencedirect.com/science/article/pii/S0140196303001071

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    11. John Doyle
      John Doyle is a Friend of The Conversation.

      architect

      In reply to Geoff Russell

      Are you saying Savory is a fraud? Or that he should have known better? Or that he is pushing a barrow for some unspecified purpose?
      Obviously, from the reception to his TED talk he came across as convincing. Your references often predate his talk which shows it's not a new idea. Certainly here in Oz grazing in small lots and moving around the herds frequently is well established, thanks to electric fencing. Is this wrong science?
      For my money I see a lot of good sense in his ideas, flaws notwithstanding [soil crusts].
      So are his photographs are not representative of his methods? What do they then demonstrate?
      Let's not throw out the "baby with the bathwater", which is what you and other critics imply.

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    12. Geoff Russell

      Computer Programmer, Author

      In reply to John Doyle

      I'm sure Savory believes what he says. But we have to decrease cattle anyway because of the methane, so the debate is moot.

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    13. John Doyle
      John Doyle is a Friend of The Conversation.

      architect

      In reply to Geoff Russell

      That's a bit of a cop out!
      You have had much to say in the link you posted above so you should be able to make a go of it
      Cattle methane is a non event.
      Think instead of warming permafrost if you want to get excited about methane.

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    14. Jack Arnold

      Director

      In reply to John Doyle

      Uhm ... I must demur John. Have you considered grass grain crops, like wheat, sorghum, millet, oats, barley etc? Some varieties of wheat produce up to 22% protein of grain weight, up to 3 tonnes per hectare depending on climate compared to beef or other animal protein. Similar protein production is found in pulses and other legumes.

      The usual conversion factor between levels is 10:1, that is, 10 tonnes of grass produce 1 tonne of beast weight yielding about 55% finished carcass weight.

      Meat production is an inefficient method of protein production compared to cropping, weight to weight.

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    15. John Doyle
      John Doyle is a Friend of The Conversation.

      architect

      In reply to Jack Arnold

      Jack, No question cattle grazing is inefficient compared to cropping. Cattle etc have their own lives to lead of course. However I am not comparing those two. I am saying grasslands that are not suitable for ploughing and cropping would be cut out of our food sources if we could not use them for grazing.
      I can't recall the figures but it is a vast area world wide.
      Also we can't impose on people who have lived on livestock for centuries, such as the maasai, and deny them their culture, which in…

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    16. Geoff Russell

      Computer Programmer, Author

      In reply to John Doyle

      What is or isn't healthy can't be determined except empirically. People have been sitting around wood fires for rather a long time but the smoke is extremely unhealthy and kills about half a million children per year among a total death toll of about 3.5 million. With a considerable illness toll is on top of that. Whether something is natural is pretty much irrelevant to whether it is healthy. Likewise dying from bacterial infections is 100 percent natural, but I far prefer antibiotics. The endogenous…

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    17. John Doyle
      John Doyle is a Friend of The Conversation.

      architect

      In reply to Geoff Russell

      Sure, no argument there. There are plenty of ways to die. New ones are discovered every year.
      Just the same natural red meat [grass fed] is preferable to doctored [grain fed etc.] red meat.

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  9. Jack Arnold

    Director

    Uhm ... a wonderful discussion, thank you people. Has anybody looked at a Macca's meat pattie ... six months after purchase??? There is a sample being circulated among school kids to encourage their understanding of the importance of preserving meat.

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  10. Chris Booker

    Research scientist

    I saw Dennis Bier (Editor in Chief of the American Journal of Clinical Nutrition) give a seminar where he tore the processed meat and cancer section of the WCRF report to shreds. The studies included had completely different definitions of what constituted 'processed' or not (i.e. definitions not standardized) and the statements of a dose-response included in the report were not backed up by the data.

    It's a pity, I've got a lot of time for the WCRF report - it's one of the largest scientific undertakings of modern times, and we need more of this systematic approach to assessing evidence. However, I really hope they update the processed meat chapter sooner rather than later as part of their ongoing Continuous Update Project. It seems to be something of a source of embarrassment in it's current form.

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    1. Rosemary Stanton

      Nutritionist & Visiting Fellow at University of New South Wales

      In reply to Chris Booker

      Chris

      The problem with definition is a real one, but when some people count sausages as processed meat and some list them among unprocessed doesn't invalidate the finding that large quantities of both processed and unprocessed meat are problematic.

      The red meat industry (through various beef/cattlemen's and other associations funded by producers) has tried to use many people to discard important research findings. I have no knowledge whether this applies to Dr Bier. Can you please supply a reference relating to the claims you make above from Dr Bier.

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    2. Chris Booker

      Research scientist

      In reply to Rosemary Stanton

      Hi Rosemary, sorry I can't supply a reference as it was at a seminar (at the University of Otago) so not published. Yes, I've no doubt that part of the debate comes from corners with vested interests.

      I guess I was picking up specifically on the processed meat question as it's the headline for the article, and the WCRF report is used to back this up, but I agree this doesn't necessarily relate to the question of overall total meat consumption.

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    3. Clare Collins

      Professor in Nutrition and Dietetics at University of Newcastle

      In reply to Chris Booker

      Chris the article IS based on the Continuous Update Project (CUP) results. Click on the words "convincing evidence" and it will take you straight there. The CUP results are presented separately for red meat alone, processed meat alone and for them combined. Also go to the WCRF-UK link http://www.wcrf-uk.org/cancer_prevention/recommendations/meat_and_cancer.php and you can download the evidence summary and advice document "Red and processed Meat: finding the balance for cancer prevention."

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    4. Chris Booker

      Research scientist

      In reply to Clare Collins

      Ah, thanks for the reply Clare. I went through the Diet and Cancer Report website earlier and saw 'Colorectal cancer' under the menu 'Cancers currently being updated' and thought that meant they hadn't done it yet!

      Anyway, now that I look through the CUP report:

      http://www.dietandcancerreport.org/cancer_resource_center/downloads/cu/Colorectal-Cancer-SLR-2010.pdf
      and..
      http://www.dietandcancerreport.org/cancer_resource_center/downloads/cu/Colorectal-Cancer-2011-Report.pdf

      ...it's interesting…

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    5. Geoff Russell

      Computer Programmer, Author

      In reply to Chris Booker

      I asked Prof Graham Giles about this back in 2008 and his Cancer Council group had run the numbers on this using his Melbourne cohort. They calculated the population attributable fraction of bowel cancer due to "more than one red meat meal per week" at 48%.

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    6. Citizen SG

      Citizen

      In reply to Geoff Russell

      aside from the anecdotal, crunching numbers from the WCRF report would indicate that eating 4 weetbix, 2 bananas and 2 apples a day equates to the risk of consuming 200g of red meat daily.

      Add an hour of exercise a day and some milk consumption and it appears that I was wrong... you should walk to the cafe, eat your bacon but upon walking home have that apple AND a glass of milk.

      At 22g for a rasher of bacon I think I'd have 2.

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  11. rory robertson
    rory robertson is a Friend of The Conversation.

    former fattie

    Professor Collins,

    I'm an economist not a scientist. So obviously I do not know all that much about the causes of cancer. But I can read, and what I've read on the Continuous Update Project's (CUP's) global investigations into cancer is somewhat unsettling.

    # On breast cancer, tobacco, alcohol, height and "body fatness" are assessed as key causes but refined/added/concentrated sugar is barely on the radar: http://www.wcrf.org/PDFs/CUP-reports-SLRs/Breast-Cancer-2010-Report.pdf

    # On pancreatic…

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    1. Sue Ieraci

      Public hospital clinician

      In reply to rory robertson

      This paper from the UK, in Critical Reviews in Food Science and Nutrition 2009, looked at the accumulated evidence on sugar consumption and various aspects of health outcomes:
      ''Is Sugar Consumption Detrimental to Health? A Review of the Evidence 1995—2006''
      http://www.tandfonline.com/doi/full/10.1080/10408390802248569#.Uk44e9KB-ro

      ''Many countries set quantitative targets for added sugars, justifying this by expressing concern about the likely impact of sugar on weight control, dental health…

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    2. rory robertson
      rory robertson is a Friend of The Conversation.

      former fattie

      In reply to Sue Ieraci

      Dr Sue,

      You appear to be encouraging readers to believe that sugar is harmless in common modern doses. Are you kidding? Are you really interested in improving public health? Look around, Dr Sue. The world is becoming fat and sick. In my opinion, it is obvious to anyone competent that sugar is a key driver of obesity and type 2 diabetes: http://care.diabetesjournals.org/content/33/11/2477.full.pdf+html

      Moreover, sugar increasingly is viewed by Australian health authorities as a key driver of…

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