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Informed consent: why some foods should carry a cancer risk warning

The evidence that smoking causes lung cancer is definitive. It took a few decades, but cigarette packs now carry prominent health warnings to alert us to this risk. When it comes to dietary patterns, convincing…

Consumers ought to know the cancer risk associated with regularly consuming some foods and drinks. Image from shutterstock.com

The evidence that smoking causes lung cancer is definitive. It took a few decades, but cigarette packs now carry prominent health warnings to alert us to this risk.

When it comes to dietary patterns, convincing evidence collated by the World Cancer Research Fund also shows that regular consumption of some foods and drinks increases the risk for specific cancers.

It’s time to begin making consumers aware of the cancer risk associated with regular consumption of particular foods and drinks, through front-of-pack warning labels.

Snapshot of cancer in Australia

It is true that the absolute risk of developing cancer is low. Last year around 120,000 new cases of cancer were diagnosed in Australia, from a population close to 23 million.

But put another way, before the age of 75 your lifetime risk of being diagnosed with cancer is one in three for males and one in four for females. Cancer is now the leading cause of disease and injury in Australia, accounting for the loss of over 550,000 years of life due to ill health, disability or early death.

The most commonly diagnosed cancers last year were prostate (18,560 cases), bowel (15,840 cases), breast (14,680 cases), melanoma (12,510 cases) and lung cancer (11,280 cases). Many of these have good treatments outcomes but approximately 117 people still die from cancer each day.

The good news is that between 1982 to 2010, the five-year relative survival after a cancer diagnosis increased for the three most commonly diagnosed cancers: from 58% to 92% for prostate cancer, 48% to 66% for bowel cancer and from 72% to 89% in women with breast cancer.

But more could be done to prevent the development of cancer in the first place, or to reduce the risk of it recurring.

So, what foods and drinks increase cancer risk?

There is convincing evidence that alcohol increases the risk of pre- and post-menopausal breast cancer, and cancers of the mouth, throat and (in men) bowel. While the official recommendation is to limit alcoholic drinks to no more than two a day for men and one a day for women, when it comes to breast cancer risk there is no safe level of intake.

There is also convincing evidence that eating more than 500 grams of cooked meat per week is risky. 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.

Alcohol, processed meat and salt increase the risk of some cancers. Image from shutterstock.com

The evidence indicates that salty and salt-preserved foods are probable causes of stomach cancer. As a result, the World Cancer Research Fund recommends avoiding these foods, not using salt when preserving foods, limiting consumption of processed foods with added salt and aiming for a low salt intake (less than six grams of salt or 2.4g of sodium) a day.

On the flip side, there is probable evidence that you can reduce your risk of bowel cancer by regularly eating garlic and foods 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%.

Eating plenty of non-starchy vegetables and fruits is associated with lower risk of cancers of the mouth, throat, oesophagus and stomach; while foods high in folate, such as green leafy vegetables, legumes, seeds, citrus fruits and fortified breads and cereals, are associated with lower risk of pancreatic cancer and diets high in calcium with lower risk of bowel cancer.

How would a labelling system work?

The food labelling process could be managed by Food Standards Australia and New Zealand (FSANZ) in the same way it currently manages health claims, which are voluntary statements made by food companies that refer to a relationship between food and health.

In January, FSANZ introduced a new standard to regulate health claims made on food labels or in advertisements. Two types of claims are now permitted: general and high-level claims.

General level health claims refer to something “in” the food and its effect on a health function, such as “calcium is good for bones”. A high-level health claim refers to something “in” the food and its relationship to a serious medical condition or an intermediate factor or risk marker for that medical condition. For example:

For every ten grams of fibre you consume per day, your bowel cancer risk reduces by 10%. Chiot's Run

Diets containing a high amount of both fruit and vegetables reduce risk of coronary heart disease.

There are 13 pre-approved high level health claim statements and 200 pre-approved general health claim statements related to foods, their health effects, and health conditions in the FSANZ code. But none of these raise the alarm for consumption patterns associated with increased disease risk.

What we need is a similar list of statements to alert consumers to potential adverse risk from consumption. These claims could be made by public health authorities relating food consumption patterns to cancer risk.

This process could be overseen by the National Health and Medical Research Council (NHMRC) which currently produces Australia’s official dietary guidelines. The NHMRC could draw on the World Cancer Research Fund’s data in areas where there is convincing evidence that foods or drinks raise the risk of specific cancers.

Government health departments and non-government agencies such as cancer councils could also be approved to submit high-level health claims for foods and beverages where there is strong evidence that consumption increases risk.

It’s time to raise awareness about what consumers can safely eat and drink, and which foods to increase or avoid to lower their cancer risk. FSANZ high-level health claims on food labels could be one such signpost.

Join the conversation

52 Comments sorted by

  1. Mike Swinbourne

    logged in via Facebook

    Should we put this label next to the one about nutrition, whether or not the product contains GMO, the best by or use by date, or the heart foundation tick of approval?

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  2. robert roeder
    robert roeder is a Friend of The Conversation.

    retired

    In regard to food labeling, the public need alerts to advise them of demonstrated risks. Politicians have been dragging their feet for a long time. Denying the people the right to choose whether to accept GMO's is scandalous. Monsanto's BT Corn is insidious, it finds its way into processed food as corn syrup. There are many other product issues.
    Pundits have been stating that the LNP is planning to sign up to the Trans Pacific Partnership Agreement. If this agreement is ratified it will become almost impossible to introduce new laws on labeling food and other ingested products. The health costs associated with poor uninformed choices will be born by the people while the mercenary corporation maximise their profits. I regard the TPPA as a crime against humanity, many other activities of corporations could be view the same way.

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    1. Reg Nansen

      Retiree

      In reply to robert roeder

      Robert, you are completely correct to describe the TPPA as a crime against humanity. Arguments about food labelling will be irrelevant if Australia signs the TPPA. Worse Australians will have no recourse for environmental, health and food vandalism.

      I urge all academics at The Conversation to educate yourselves about this agreement, to insist that the text be made public prior to commitment and to insist that Australia retain its sovereignty in values and aspirations by NOT signing on to the TPPA. "EU-US historic trade deal: ‘Putting the corporation above the nation’" http://rt.com/business/eu-us-trade-brussels-528/

      The TPPA will see the end of democracy as we know it.

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    2. John Pickard

      Eclectic naturalist

      In reply to Reg Nansen

      Robert and Reg , you are absolutely correct about the TPPA.

      Without putting too fine a point on it, the Australian government is spreading OUR cheeks for the US. The idea that an overseas company can challenge our laws to sell their shit here is nothing short of a complete sell-out. Plus of course, the changes to IP which will give US companies almost unfettered rights to bulldoze us yet again. And US big pharma will kill our PBS.

      But will Anthony John (climate change is crap) Abbott change it? Not bloody likely! To do so would offend his mentor John Winston Howard.

      Sometimes I despair of being an Australian.

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  3. Andy Cameron

    Care giver

    "The evidence that smoking causes lung cancer is definitive."
    Stated this way, I am afraid, I would have to give the argument a "Fail".

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  4. Andy Cameron

    Care giver

    "but cigarette packs now carry prominent health warnings to alert us to this risk."
    That was to balance the complete and utter lie of Big Tobacco (legally-sanctioned) that there was NO link at all between cigarette smoking and cancer.

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  5. James Jenkin

    EFL Teacher Trainer

    This sounds like a lot of labels on food. Is there a point where there's too much information and we switch off?

    We focus on labelling food, when there are so many risks around us all the time. Yet no-one proposes signs saying 'Don't eat this dirt' or 'Don't lie face down in this drain'. We seem to assume parents and schools will teach us these things. What makes food different?

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  6. John Pickard

    Eclectic naturalist

    Sometimes I wonder how I managed to get to my superannuated age while eating pretty much anything on the plate in front of me. Having said that, I try to avoid most processed foods despite their convenience.

    Given the power of major "food" companies, and the way that FSANZ is a toothless lap-poodle of the industry (very much like the useless and gutless Therapeutic Goods Administration or whatever it is called), I don't see much change in the future.

    But why focus just on food?

    What about…

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

    former fattie

    Professor Collins,

    Do you think that processed food/drink products with added sugar should carry "front-of-pack warning labels"?

    After all, modern rates of (added) sugar consumption - including via sugary drinks - are a key driver of global obesity, type 2 diabetes and heart disease.
    Moreover, like tobacco and alcohol, sugar appears to be carcinogenic: http://www.youtube.com/watch?v=xDaYa0AB8TQ&feature=youtu.be

    Readers, between minutes 26 and 28 in the link above, prominent US cancer…

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    1. Clare Collins

      Professor in Nutrition and Dietetics at University of Newcastle

      In reply to rory robertson

      Rory
      Have a read of the WRCF evidence report the article hyperlinks to for a summary of the graded evidence statements relate dto prevention of nutrition related cancers.

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

      former fattie

      In reply to Clare Collins

      Professor Collins,

      Thanks for your response. Perhaps a truncated version of my just-now-retracted post will enjoy a longer lifespan.

      As I mentioned, I think I recall from my earlier discussions with Rosemary Stanton on this matter that the WRCF evidence features "body fatness" as a key risk factor for prostate, bowel, and breast cancers (or was it for just two of the three?). Accordingly, we should not be surprised that sugary food/drink products that promote obesity, type 2 diabetes and…

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  8. Margo Saunders

    Public Health Policy Researcher

    Clare, your suggestion is absolutely consistent with the recommendation that I would make, based on the weight of recent evidence about processed meat and bowel cancer. It seems to me to be a complete failure of consumer health information that ham, bacon and other processed meats -- whether sliced-to-order at the deli or pre-packaged -- carry no point-of-purchase information about bowel cancer risks.

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    1. Clare Collins

      Professor in Nutrition and Dietetics at University of Newcastle

      In reply to Margo Saunders

      Margo, thanks you for your support. I believe it does need wide debate as seems imprudent to only allow cliame relate dto decreased risk and not increased risk.

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    2. Margo Saunders

      Public Health Policy Researcher

      In reply to Andy Cameron

      Public-health bashing will do little to ensure that preventive health is taken much more seriously, especially by the traditional sceptics who tend to use anti-government, pro-libertarian arguments to disguise the facts that they (a) don't want to be troubled or confused with information and (b) don't want to be told 'what to do' by governments or health authorities when it comes to how to live their lives. But then, they do regret their years of life needlessly lost or the serious erosion of their…

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    3. Andy Cameron

      Care giver

      In reply to Margo Saunders

      "I have known a few 'public health czars' during my 28 years in public health policy, and 'drunk on power' is not exactly how I would describe them"
      But of course, you would say that, wouldn't you? ;) No-one is "public health" bashing. We are just increasingly casting a critical eye over what has become a very large and expensive tax-payer funded industry. Hence, the raised eyebrows on the Dutch example. The health of the public, and the health of the academic industry are NOT the same thing.

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  9. Paul Prociv

    ex medical academic; botanical engineer

    Thanks for this article, which contains much food for thought (sorry!). You mentioned ham and bacon, but omitted other smoked foods, e.g. kippers, smoked oysters etc.. Any health issues with those, if eaten too often? Does preparation of food by smoking (inevitably accompanied by salting) render it significantly carcinogenic?

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

      former fattie

      In reply to Andrew Smith

      Andrew, the University of Sydney's highest-profile food specialists tell a quite different story on sugar: http://www.australianparadox.com/pdf/diabetes.pdf ; http://www.theaustralian.com.au/news/health-science/a-spoonful-of-sugar-is-not-so-bad/story-e6frg8y6-1226090126776

      Unusually for a Group of Eight university, the University of Sydney has deep links to the sugar and sugary food/drinks industries: http://www.srasanz.org/about-us ; http://www.logicane.com/Partners ; (scroll down) http://www.gisymbol.com/products-2

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    2. Sue Ieraci

      Public hospital clinician

      In reply to Andrew Smith

      ''if we had our time again sugar, salt and vinegar would be controlled substances, due to their inherent unhealthiness....''

      That would only work if we had invented refrigeration a few millennia earlier...

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

      former fattie

      In reply to Sue Ieraci

      Sue,

      I think most readers assumed the reference to "our time again" spanned the period since modern refrigeration; a period that has featured elevated rates of diet-related maladies including obesity, type 2 diabetes and various cancers. I assume you are not part of the food-industry-service-provider crew claiming that (harmful) added sugar is a yummy, harmless and necessary part of our food supply.

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    4. Azra Mayer

      logged in via email @mail.com

      In reply to Andrew Smith

      Vinegar should not be vilified alongside of isolated sugar.

      Naturally fermented, sugarless vinegar is proving to have many health effects; scientific evidence is emerging to support this ancient health claim.

      Three examples:

      Kondo S, Tayama K, Tsukamoto Y, Ikeda K, Yamori Y. Antihypertensive effects of acetic acid and vinegar on spontaneously hypertensive rats. Biosci Biotechnol Biochem. 2001;65:2690–2694. [PubMed]

      (Though, of course acetic acid is not vinegar - the latter containing a wide range of food components, such as vitamins, minerals, amino acids, polyphenols,...).

      Johnston CS, Kim CM, Buller AJ. Vinegar improves insulin sensitivity to a high carbohydrate meal in subjects with insulin resistance or type 2 diabetes mellitus. Diabetes Care. 2004;27:281–282. [PubMed]

      Nanda K, Miyoshi N, Nakamura Y, et al. Extract of vinegar "Kurosu" from unpolished rice inhibits the proliferation of human cancer cells. J Exp Clin Cancer Res. 2004;23:69–75. [PubMed]

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  10. Sue Ieraci

    Public hospital clinician

    Could we make a distinction between known carcinogenic substances and those associated with population health risks?

    Sugar, for example, is not a carcinogen. Even if it contributes to obesity, which is associated with increased risk of various diseases, it is still not directly carcinogenic. At the other extreme, substances in tobacco smoke are known to be directly carcinogenic.

    I found an interesting 1994 editorial from a group of Japanese authors relating to heterocyclic amines from cooked…

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

      former fattie

      In reply to Sue Ieraci

      Sue,

      I prefer a "balance of risks" approach to protect public health. Globally renowned cancer expert Professor Louis Cantley says added sugar "scares" him because it causes/promotes cancers: (minutes 26-28)
      http://www.youtube.com/watch?v=xDaYa0AB8TQ&feature=youtu.be

      Accordingly, he tries to eliminate it completely from his diet. Why is that not the right approach for our dietary guidelines, particularly as added sugar is known also to be a key driver of obesity and type 2 diabetes? http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2963518

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

      former fattie

      In reply to rory robertson

      How this for timing? Just today, the Sydney University Nutrition Research Foundation and Sugar Australia et al combined to launch a public-relations campaign to claim that while sugar is really yummy, it is not a problem for public health:

      "With so many conflicting headlines, it is no wonder consumers and health professionals are getting confused about sugar and its role in nutrition and health...[we] announce the launch of an evidence-based online information hub": http://www.srasanz.org

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  11. John Davidson

    logged in via Facebook

    The evidence that smoking causes lung cancer is definitive. It took a few decades, but cigarette packs now carry prominent health warnings to alert us to this risk.

    WHAT EVIDENCE THERE IS NONE!

    JOINT STATEMENT ON THE RE-ASSESSMENT OF THE TOXICOLOGICAL TESTING OF TOBACCO PRODUCTS"
    7 October, the COT meeting on 26 October and the COC meeting on 18
    November 2004.

    http://cot.food.gov.uk/pdfs/cotstatementtobacco0409

    "5. The Committees commented that tobacco smoke was a highly complex…

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  12. John Davidson

    logged in via Facebook

    This pretty well destroys the Myth of second hand smoke:

    http://vitals.nbcnews.com/_news/2013/01/28/16741714-lungs-from-pack-a-day-smokers-safe-for-transplant-study-finds?lite

    Lungs from pack-a-day smokers safe for transplant, study finds.

    By JoNel Aleccia, Staff Writer, NBC News.

    Using lung transplants from heavy smokers may sound like a cruel joke, but a new study finds that organs taken from people who puffed a pack a day for more than 20 years are likely safe.

    What’s more, the…

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  13. David Colquhoun

    Professor of Pharmacology, UCL at University College London

    The policy advocated here would be justified only if we were sure of the risks. Unfortunately WCRF greatly exaggerated the risks of eating red meat. In their revision the risk was halved, and in the recent EPIC study of Europeans there was essentially no risk at all (something that isn't mentioned here).

    The great epidemiologist, John Ioannidis, has recently pointed out the totally unreliability of the sort of observational epidemiology on which the risks cited here are based. Read about it at http://www.dcscience.net/?p=6300

    I'm not against warning labels and taxes as a matter of principle, but they need to be based on reliable information. But we know little about the effect of diet on health. That’s why so much is written about it

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    1. Clare Collins

      Professor in Nutrition and Dietetics at University of Newcastle

      In reply to David Colquhoun

      We know enough about diet and disease risk to at least let the general public in on some of the evidence. let see what the meta-analysis says when EPIC is included but meanwhile not discount any diet -disease links

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    2. David Colquhoun

      Professor of Pharmacology, UCL at University College London

      In reply to Clare Collins

      Thanks very much for the response. But I'm not sure that meta-analysis helps in a case like this. The point is that observational data have proved to be totally unreliable. Pooling a lot of unreliable data does not give you a correct result.

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    3. Clare Collins

      Professor in Nutrition and Dietetics at University of Newcastle

      In reply to David Colquhoun

      David
      if you choose to give no advice or to stifle discussion because of the limitations related to collecting dietary intake data - then I believe that is a copout. We know there can never be adequate randomised controlled trials due to the methodologiocal and practical issues. Surely one cannot argue with advice to eat more plant based foods and drink less alcohol - whilst having a debate about the current - but best available - evidence related to consumption about specific foods the WCRF have evaluated as being associated with increased risk for specific cancers.

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

      former fattie

      In reply to Clare Collins

      I agree on the alcohol point. But careful on the plant-based foods description, Clare, as added sugar is both plant-based and a fuel for cancers: minutes 26 to 29 at http://www.youtube.com/watch?v=xDaYa0AB8TQ&feature=youtu.be

      Let's make a distinction between fresh foods and processed foods. I'm unconvinced by the idea that anyone is getting fat and sick via fresh foods. I agree with Margo that warning labels are in order for some processed foods, and if processed meats are labelled, then sugary softdrinks should not be left alone: http://www.rethinksugarydrink.org.au/

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    5. David Colquhoun

      Professor of Pharmacology, UCL at University College London

      In reply to rory robertson

      I'm afraid that the idea that refined sugar is somehow worse for you than natural sugar has no basis in reality whatsoever. And honey, which is rather high in fructose, might be the worst of the lot.

      The "fuel for cancers" story is no better than quackery.

      My conclusion, at http://www.dcscience.net/?p=6300 is that almost all that one can say, after mountains of work, As far as I can guess, the only sound advice about healthy eating for most people is
      1. don’t eat too much
      2. don’t eat all…

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

      former fattie

      In reply to David Colquhoun

      David, if you're happy to say that Louis Cantley is a quack, then fine. He might say the same of you. Actually, I find him and his sugar/cancer explanation quite credible. After all, we know that sugar is a key driver of obesity and type 2 diabetes - http://care.diabetesjournals.org/content/33/11/2477.full.pdf - and that key cancers are correlated with "body fullness". It would be surprising if there were no link of causation from elevated sugar consumption to overweight/diabetes and cancer. That's…

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    7. David Colquhoun

      Professor of Pharmacology, UCL at University College London

      In reply to rory robertson

      I'm not saying that Cantley is a quack. But he does take a very extreme view which can't be justified by the evidence, and isn't shared (in that extreme form) by most people in the field.

      When little is known about the field it tends to be dominated by zealots, each of who claims to have the one true answer. Unfortunately there is little unanimity between the various camps.

      As I have said before, I deplore that addition of sugar to almost everything we eat. But mostly because it makes it hard to not eat too much. There is really no reason to think that sugar is a carcinogen, as Sue Ieraci has already pointed out.

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  14. David Colquhoun

    Professor of Pharmacology, UCL at University College London

    The analogy with warnings on cigarettes doesn't really work. Cigarettes produce a huge increase in risk, 20-fold or so, and although there has been no RCT, nobody now doubts that they cause lung cancer.

    In contrast, even the first WCRF estimate for relative risk for eating red meat was 1.2, and that has been decreasing with every subsequent piece of work.

    The danger of using warning labels on the basis of such flimsy evidence is that people will simply ignore them. even when they are very well-justified. Crying wolf is not a good idea.

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    1. Clare Collins

      Professor in Nutrition and Dietetics at University of Newcastle

      In reply to David Colquhoun

      Many young women have no idea of the evidence on alcohol consumption and increased risk of breast cancer. Lets open up the debate to those affected by these conditions.

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    2. Margo Saunders

      Public Health Policy Researcher

      In reply to Clare Collins

      And, to get back to one of the main points of the article, the current weight and direction of evidence are sufficient to justify health warnings on processed meats (ie, products containing nitrates/nitrates). Processed meat consumption has been found to increase the risk of bowel cancer by twice as much as the same amount of red meat, and recent European findings have highlighted the links between processed meats and heart disease, as well as cancer. Yet these products continue to be widely available, heavily promoted, and regularly consumed in significant amounts.

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    3. David Colquhoun

      Professor of Pharmacology, UCL at University College London

      In reply to Margo Saunders

      I simply don't agree with our assertion that the evidence is sufficient. More to the point, neither does John Ioannidis.

      I think you misrepresent the European data. One could say that in the EPIC trial the risk from processed meat appeared to be infinitely greater than the risk from red meat, because the latter was essentially zero. It would be more helpful to say that the relative risk for processed meat was between 1.09 and 1.18 (depending on what adjustments were made) -see the discussion…

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

      former fattie

      In reply to David Colquhoun

      Similarly, and perhaps more importantly, David, the "red meat causes cancer" story typically makes no effort to separate out the influence of sugar, which tends to enter the diet of individuals and populations at the same time - and in similar doses of energy - as meat. Here is an important chart - showing that sugar/meat correlation - that I think invalidates a chunk of the "red meat is a problem but we haven't really looked at sugar yet" analysis that tends to get waved around: http://www.australianparadox.com/part-2

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    5. Margo Saunders

      Public Health Policy Researcher

      In reply to David Colquhoun

      Researchers acknowledge that we need more information about how the association between processed meat and disease actually works, but there are plenty of examples in public health about the perils of waiting for this sort of information before taking preventive action.
      In their paper on processed meats and CVD ('Processing of meats and cardiovascular risks: time to focus on preservatives', BMC Med, May 2013), Micha and colleagues note, in relation to their findings and those of the EPIC study: 'The absence of associations of processed meat intake with biologically unrelated causes of death supports a low likelihood of confounding as an explanation for the observed higher risks of CVD and cancer deaths.'

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    6. David Colquhoun

      Professor of Pharmacology, UCL at University College London

      In reply to Margo Saunders

      Well the whole argument is whether or not there really is and "observed higher risks of CVD and cancer deaths". In Europeans at least, it seems that there is little or nothing to be explained.

      When you say that there are "plenty of examples in public health about the perils of waiting for this sort of information before taking preventive action". The only example that I can think of is cigarette smoking. What did you have in mind?

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    7. Margo Saunders

      Public Health Policy Researcher

      In reply to David Colquhoun

      Re where earlier action and the application of the precautionary principle might have saved many lives: in addition to tobacco use (certainly the big one), examples cited in the public health literature include delays in addressing the health risks associated with lead in paint and in petrol, with the handling of asbestos in building material (and synergistic relationships with smoking), some road safety issues, and health risks from ionising radiation, benzene, DES and Creutzfeldt-Jakob Disease (‘mad cow disease’).

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    8. David Colquhoun

      Professor of Pharmacology, UCL at University College London

      In reply to Margo Saunders

      I wouldn't disagree with any of them, but for most of them the toxicity is much bigger, and much more obvious. than in the case of meat.

      Perhaps the question should be put the other way round. If a label were added to food every time a survey suggested toxicity there would be so many labels that they'd become useless. Worse still. the colour of the labels would change whenever the next unreliable data contradicted the previous unreliable data (as it frequently does).

      The fact of the matter is that observational epidemiology gives utterly unreliable data. Having huge numbers of people in the survey doesn't help. In fact it allows one to detect smaller correlations without helping at all with the crucial question of causality. Please read Ioannidis, ore even the journalist Gary Taubes, who explained the problem very clearly in the New York Times. See http://www.dcscience.net/?p=1435

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

      former fattie

      In reply to David Colquhoun

      David,

      I have had a quick read of your piece linked above - "Diet and health. What can you believe: or does bacon kill you?" - early in my morning. As an economist, I found it fascinating. I shall be going back to read more on the topic when I get some time on the weekend, or at least some time after I have had my mutton chops and eggs for breakfast and got my boys off to school.

      I must say that my fumbling round in the nutrition space over the past couple of years has been eye-opening. Much…

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    10. David Colquhoun

      Professor of Pharmacology, UCL at University College London

      In reply to rory robertson

      Rory

      On the question of vocabulary, I'd assume that 'relation', 'correlation' and 'association' all mean much the same thing. It is impossible to attribute 'cause' on the basis of observational data alone. To do that, randomisation is essential. That's just basic statistics.

      One of the things most strongly correlated with longevity is income (or some would say inequality of income). And smoking, sugar intake and meat consumption are all correlated with income. In order to isolate the…

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    11. David Colquhoun

      Professor of Pharmacology, UCL at University College London

      In reply to rory robertson

      I wasn't aware of the Australian Paradox. I must agree that the evidence for a decline in sugar consumption is negligible. And I also agree that the idea that sugar does NOT cause type 2 diabetes is far from being a consensus view. As you say, debate continues to rage about that question. Nevertheless I have yet to see unambiguous evidence that it DOES cause diabetes.

      One thing we do know that correlates with obesity is total calorie intake and the addition of sugar to everything makes…

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

      former fattie

      In reply to David Colquhoun

      David,

      Thanks very much for coming back. My Dad too was a smoker, averaging perhaps 70 day for most of 60 years, and a very heavy drinker for the first 40 years of my life. Not good. Then his body ran out of steam, started shutting down and forced him to stop drinking and smoking. He's still alive and he's still my Dad, but at age 80 his body is a shambles. Naturally, I put that down to the smoking and drinking, not to the meat consumption - including bacon and sausages - that has been a big chunk…

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