Can red meat cause cancer? A voice of reason
Unless you’ve been hiding under a rock, you’ll know that earlier this week the World Health Organisation declared processed meat as definitively carcinogenic to humans and red meat as “probably” carcinogenic. Within hours my inbox had exploded and my intern Sarah checked in to test the waters. She’s aware that I have a deep affection for bacon. Obviously I love kale and quinoa and broccoli too, but I love them best with bacon. It’s an occasional habit, honestly!
As a nutritionist and an avid follower of dietary trends and analysis, I found this one interesting. Vegetarians and vegans rejoiced and the media cranked out a combination of sensationalist and alarmist headlines. Carnivores wept and Twitter became the venue for massive amounts of bacon-related defiance and hilarity: @thepun ningman: “In your face, World Health Organisation. The bacon I bought this morning said it was cured.” Ha ha!
So, while acknowledging my bacon-loving bias, I started to investigate, trying to find some objectivity among all the hysteria. An unexpected part of my job has to become a voice of reason in dietary debate. The food industry is heavily driven by profit, mainstream science can seem blinkered and reductionist, the holistic/complementary/alternative industry can be just as guilty of sensationalism as the media — no wonder people get overwhelmed with conflicting messages and information overload. So let’s take a moment to pause and look at all of this rationally.
Firstly, the news that processed meat is carcinogenic (cancer-causing) is not new. Studies going back to the 1970s have found associations with stomach, bowel and colorectal cancers. Those findings are consistent and shouldn’t necessarily be surprising — especially if you’ve seen documentaries like Food, Inc (essential viewing). So you mean Spam and hot dogs aren’t good for us? Shock, horror! Come on everyone, whether you want to believe it or not, it’s hard to see how processed meat can be either health-promoting or nourishing in any shape or form.
However, in a step that put the final nail in the coffin, earlier this year the International Agency for Cancer Research gathered 22 scientists from ten countries to review 800 epidemiological studies regarding processed meat and red meat intake. To be clear, “processed meat” included anything salted, fermented, cured, smoked or otherwise processed to enhance flavour or improve preservation. “Red meat” included beef, veal, pork, lamb, mutton, horse, goat and any associated offal or meat by-products such as blood.
In respect to processed meat, the IACR conclusion was that “on the basis of the large amount of data and the consistent associations of colorectal cancer with consumption of processed meat across studies in different populations, which make chance, bias, and confounding unlikely as explanations, a majority of the working group concluded that there is sufficient evidence in human beings for the carcinogenicity of the consumption of processed meat”. Did I lose you? This basically means that even when taking into account the possible influence of other contributory factors, that the data still shows a clear correlation between intake and cancer risk. It should be noted that the dose-responsive nature of this was “statistically significant”. For example, a 50g daily portion of processed meat increased risk of bowel cancer by 18 per cent and that risk climbed with further consumption.
Ultimately, this has led to the classification of processed meat as a “top-tier” carcinogenic substance, alongside alcohol, cigarettes and asbestos. However, whilst this has been used to generate alarmist headlines such as “Bacon is as dangerous as smoking!” this does not mean it is equally dangerous. It’s a little tricky to grasp but the IARC says “….the classifications describe the strength of the scientific evidence about an agent being a cause of cancer, rather than assessing the level of risk.” So the science relating to the carcinogenic properties of processed meat is just as strong as the science relating to smoking, but the overall risk from smoking is higher. But remember, we already knew that processed meat was bad for us. The real “news” is that red meat is carcinogenic too, yes? Not quite. Remember, the press release says that red meat is “probably” carcinogenic and the IARC paper published in the Lancet (which provides much more detail) says “chance, bias, and confounding could not be ruled out with the same degree of confidence for the data on red meat consumption, since no clear association was seen in several of the high quality studies and residual confounding from other diet and lifestyle risk is difficult to exclude. The working group concluded that there is limited evidence in human beings for the carcinogenicity of the consumption of red meat”.
This issue of confounders really lies at the heart of this debate. As far as I understand it, in a scientific study, a confounder is an additional, unobserved, potential cause of the outcome being studied. So, for example, imagine you were doing a study to see if coffee contributed to the development of lung cancer, but you didn’t take smoking as a risk factor into account, then smoking would be the confounder. In my opinion, the problem with the assessment of red meat so far is that there are confounders galore and many of them are not being discussed within mainstream review.
For example, it would seem sensible to look at grass-fed vs factory-farmed red meat given that cattle farming methods significantly affect the quality of what we eat. Grass-fed beef has a higher omega three and conjugated linoleic acid (good for fat-burning) content, as well as more beta-carotene and a variety of other antioxidants. It seems logical that meat from a healthy, free-range animal would be healthier than an animal from a factory farm having never seen a blade of green grass.
Also, I wonder what percentage of people who eat red meat (even healthier red meat), perhaps also eat fewer vegetables? As plants help to prevent DNA damage and promote repair, the more vegetables we eat, the lower our risk of cancers (especially colon/bowel cancers). So is the link between red meat and these cancers more to do with the meat, or more to do with the vegetables? Likely it’s an interplay of both and it’s worth considering.
Finally, given that most of us have known the health-risks associated with processed meat for some time, it seems logical to me that people who eat lots of processed red meat, might also care less about their diet in general and so may also be consuming more sugar and more trans fats too. These have also been linked to carcinogenic activity, so isolating carcinogenic factors becomes very complicated. • The advice given in this article is not intended to replace medical advice, but to complement it. Consult your GP if you have health concerns. Catherine Burns BA Hons, Dip ION is the managing director of Natural Ltd and a fully qualified nutritional therapist trained by the Institute for Optimum Nutrition in the UK. She is not a registered dietitian. For details, please go to www.natural.bm or call 236-7511. Join Catherine on Facebook: www.facebook.com/nutrifitandnatural nutritionbermuda
Include small portions of good quality red meat in your diet within these guidelines:
1. Avoid processed meat the vast majority of the time. Remember this includes ham, bacon, sausages and any meat item (turkey/chicken included) that has been salted/cured/fermented/smoked or otherwise “preserved”. If you are going to have it, try choosing an ethical brand such as Applegate or Niman Ranch. If you or your children rely on deli meat for lunch boxes, try hummus and cucumber, nut butter and fruit-only jam, home-roasted organic chicken, avocado and tomato …. there are lots of options!
2. Pick good quality, grass-fed (and preferably organic) red meat options, occasionally. Try grass-fed beef or lamb (eg the Dakota grass-fed beef or the New Zealand lamb at Supermart) in small portion sizes (1/4 of your plate max). Grass-fed meat tastes different — it is more rich and has an intense flavour, so a little goes a long way. It’s more expensive so to manage the costs, dilute it prolifically with beans, lentils and vegetables — and have it less often.
3. Regardless of whether you are having red meat or not, always fill half your plate with non-starchy vegetables or salad. These are packed full of cancer-preventing antioxidants that help to neutralise oxidative damage in the body.
4. Be careful how you cook red meat. Processing red meat triggers the formation of cancer-causing chemicals such as n-nitroso-compounds and polycyclic aromatic hydrocarbons. Cooking even good quality red meat at a high temperature also forms PAHs and heterocyclic aromatic aminos.
5. If you’re vegetarian or vegan, be a healthy one! There’s no animal products in Oreos or Diet Coke but they are arguably carcinogenic too (especially on a large scale). Get your veggies in and stick to good quality vegetarian protein instead of processed veggie burgers and sausages.
6. Remember, although it’s a huge part of the picture, nutrition is not the whole picture. Managing stress, taking exercise and staying well hydrated (with water!) are all important too.
