Red Meat and Cancer

By Emily White

I was scrolling through Facebook the other day (as I do all to often) and came across an article which annoyed me more than it probably should have. It was suggesting that eating red meat is literally killing you and that avoiding red meat will see you live longer, happier, smarter, slimmer …you get the idea. Basically bottom line, if you eat red meat.. you will get cancer… and you will die.
 
So first lets look at why everyone thinks this is the case. Numerous organisations around the world have said that eating red and processed meats can increase risk of some cancers. For starters, putting fresh red meat and processed meats into the same cancer causing category is ridiculous.. But more on that later. 

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The biggest problem with the red meat is going to kill you saga is the type of research put forward. Most of the data on this topic is gathered through observational studies. Observational studies are ones, which you observe a person and particular lifestyle factors (such as whether or not they eat red meat) and compare it to health outcomes. This is in comparison to an experimental study whereby they intentionally introduce a treatment (in this case a diet) and a result or outcome is observed. 
 
Observations are a great place to start in research, but are severely limited by confounding and therefore can never imply causation. Cats will be doing algebra before you can imply causation from an observational study. Lets take red meat as an example. Someone who is a vegetarian (for reasons other animal welfare) has taken a conscious decision to try and improve his or her health (whether or not this actually improves health outcomes is a great debate for another day!). What this means is that this person may be more likely to also exercise, eat more vegetables and fruit, and have a lower chance of smoking and engaging in other unhealthy activities which could influence cancer risk (1,2).  Or alternatively with the rap red meat has been getting lately, someone who eats it freely may also be eating it in the form of a pattie, surrounded by a thick white bun, with vegetable oil fried chips and a glass of coke…. see where I’m going with this?
In a study done in 2012, it found that those who ate the most red meat were more likely to die of cancer or CVD (3). However those who ate the most red meat were the least physically active, were more likely to smoke, and least likely to take a multivitamin. While researchers do their best to adjust for these confounders it really is a difficult, if not impossible task.
 
So what is it that is ‘so bad’ about red meat? 
While it is difficult to pin point what it is in red meat that is apparently so bad for you, a lot of the literature leans towards heterocyclic amines (HCA) and polycyclic aromatic hydrocarbons (PAH).  Now your probably thinking what on earth those are and how they relate at all to red meat. These are potential carcinogens (4) formed on meat, when it is scorched or blackened (think dad on the BBQ). Other possibilities outlined in the literature are the nitrate or nitrates used in the making of certain processed meats such as bacon (5). Thereby if you are not eating processed meats regularly, and you aren’t overcooking or charring your meat you are potentially limiting the risk even further.
 
For those that eat it, meat is a great source of many essential nutrients such as iron and zinc. Red meat and the kidneys of sheep and cattle are also great sources of selenium, which can be difficult to obtain elsewhere, as NZ soils are very selenium depleted. Interestingly low selenium has been implicated as a risk factor for certain types of cancer (6) so ensuring you get enough is important! Fattier cuts of meat are also more satiating which is extremely important when trying to maintain a healthy diet.
 
Assuming you aren’t downing nitrate- filled processed meat like it’s going out of fashion and are seeking good quality grass-fed red meat you shouldn’t really be too concerned. The biggest issue with red meat appears to be how it is prepared so stick with gentler cooking methods (slow cooking, casseroles, or gently frying) as often as you can. As with everything in life- moderation is key, but enough with the demonising red meat people!

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​References: 

1.         LaFleur J, Nelson RE, Sauer BC, Nebeker JR. Overestimation of the effects of adherence on outcomes: a case study in healthy user bias and hypertension. Heart. 2011;97(22):1862-9.
2.         Shrank WH, Patrick AR, Alan Brookhart M. Healthy User and Related Biases in Observational Studies of Preventive Interventions: A Primer for Physicians. Journal of General Internal Medicine. 2011;26(5):546-50.
3.         Pan A, PhD, Sun Q, Md, ScD, Bernstein AM, et al. Red meat consumption and mortality: Results from 2 prospective cohort studies. Archives of Internal Medicine. 2012;172(7):555-63.
4.         Cross AJ, Ferrucci LM, Risch A, Graubard BI, Ward MH, Park Y, et al. A large prospective study of meat consumption and colorectal cancer risk: an investigation of potential mechanisms underlying this association. Cancer Res. 2010;70(6):2406-14.
5.         Miller PE, Lazarus P, Lesko SM, Cross AJ, Sinha R, Laio J, et al. Meat-related compounds and colorectal cancer risk by anatomical subsite. Nutr Cancer. 2013;65(2):202-26.
6.         Meplan C, Hesketh J. The influence of selenium and selenoprotein gene variants on colorectal cancer risk. Mutagenesis. 2012;27(2):177-86.