Meat and Disease Risk - Explained.

Over the last decades, much consideration has been given to disease risk and meat in the diets. Some diseases include cancers and heart disease.  

 Firstly, animal products – these are any products that come from animals (meat, poultry, offal, eggs, diary produce etc). Like any food category there are better quality and lesser quality options. In general, red meats (beef, pork and lamb) have more saturated fat (bad), however lean red meat options are also available.  Importantly, many animal products provide essential nutrients such as protein and iron. 

 Why is research showing a link between meat and disease? 

 Red meat and even poultry has been linked to various diseases (including cancer and heart disease). Some examples:

 

Image 1: Classification of Potential Disease and Meat

Image 1: Classification of Potential Disease and Meat

1.   The International Agency for Research on Cancer (IARC), determined meat increased risk of colon cancer by 18 percent (6) – suggesting the headline that Meat causes cancer. 

 

2.   A very recent research stated “A higher meat intake could slightly increase your risk of heart and circulatory problems and an early death, according to research from the US” (5) – suggesting that meat is linked to greater heart disease risk. 

 

And the other side:

3.   “The possible absolute effect of red and processed meat consumption on cancer mortality and incidence are very small, and the certainly od evidence is low to very low” (1)

 People’s first instinct is to quickly remove meat from the diet. However, research isn’t as simple as A = B. Let me simplify some of these so you can avoid misinterpreted and fear producing headlines in the media.

Tip – if you want the quick conclusion skip down to “Where does this leave us”.

 Quality of Meat

High quality animal sources can have great benefits for health (Processed meat- doesn’t tend to fall into this category – cured, lunch meat, canned, jerky).  Research has shown that the long term consumption of processed meat had a greaterassociated with heart related disease risk (3; 4) – Suggesting that processed meat may not be optimal for health. It is reported that a daily portion of processed meat of 50g(approximately the amount of one hotdog or six slices of cooked bacon) is the amount of processed meats deemed “carcinogenic” (6) (interestingly placing it in the same category as smoking).

 – Are you going to get cancer from the next hot dog?– Well… not exactly. As stated, a daily average of 50g – meaning occasional inclusion of such items doesn’t appear to be detrimental to health.Therefore, this falls into a balanced diet with moderation of some food groups.  

Cooking Methods

Cooking methods can largely alter the chemical composition and nutritional value of food (2).Reported intakes in research indicate how food was cooked, for example – if beef was deep fat fried it can add saturated fat to a meal, which potentially in overconsumption can lead to health issues.

-  So if you want to minimise the risk – consider your looking methods – choose to bake poach or grill over deep fat frying. 

Quantity of Meat

 Intakes no greater than 70g/day of red/processedmeats to prevent disease are advised  (8).  Research demonstrated that average daily portions of 120gof red meat was linked to greater heart disease (5).

- What does this mean –  This is grossly over the recommended intake for health, therefore no surprise meat intake was linked to health issues.

Image 2

Image 2

 It also raises questions around portions sizes. Larger portion sizes may lead to calorie overconsumption potentially leading to overweight individuals – it is well established that obesity (and other factors) increase the risk to a broad spectrum of diseases.

Nevertheless – Meat overconsumption (like so many other foods) appears important to disease risk. 

 

Other risk factors for disease 

High blood pressure, smoking, physical inactivity, obesity, unhealthy overall diet are all known risk factors for disease risk, all which are shown to be greater risk factors for disease development then red meat (7).

 If you are to look deep into research factors – many of these co-existing factors are apparent (5), therefore when multiple factors exist, you cannot determine that X (meat) causes y (disease). There is stronger research suggesting other areas that have greater risk to disease (5) (as mentioned above). 

 

If you are looking at ways to minimise disease risk,  ensuring you don’t smoke, aren’t overweight, are physical active and optimise a well-balanced diet appears much greater to reduced risk then simple cutting out meat. 

Image 3

Image 3

Final note: Our likelihood of developing cancer in our lifetime is 5%. Research that suggested an increased risk of 18% of colon cancer is the relative risk,however the relative risk of actually developing cancer throughout a lifetime may only increase by 1% (from 5- 6%) , the absolute risk(see image 3). I am not underplaying risk factors for disease, simply showing that sometimes data is  misunderstood in real world application can mislead people. 

 So where does this leave us? 

Firstly, most research that link meat with diseases, does so often only by association -  not cause.In other words there has been a observed trend of disease risk noticed with high processed meat consumption – there has not been research to show that eating meat directly increased disease risk. Therefore, a number of variables are at play that can account for these associations. As the old saying goes - “anything in moderation”.It seems to play a vital role in this discussion. Misconstrued interpretation of research leads to misleading headlines, in result criminalising foods.

 What we do know is that there is an associated link to disease and excessive intakes of processed meats and red meats. However, there is a question mark to whether the cooking methods and other disease causing variables (ie. obesity, physical inactivity, high intakes of saturated fats and smoking) are in fact a large contributor to this increased risk.

 It would appear that many findings within the research  that directs us to possible cut down if you consume excessive meats – however eating within the recommendations for meat is probably safe. Meat also can provide us with many beneficial compounds including iron, protein which are essential for health.

 

Image 4

Image 4

Take Home: Including high quality lean sources of meat, as part of a well-balanced diet, appears to be safe if two criteria are met:

-       Moderate intake of lean red meat

-      Reduced consumption of processed meats.

 Most importantly -  if you are serious about reducing the risk of disease – you should address the areas with much stronger evidence around the health risks. Obesity, physical inactivity, smoking and overall poor diet lead to more deaths than a single hot dog or a bacon rasher ever will.

References: 

 1.    Han, M. A., Zeraatkar, D., Guyatt, G. H., Vernooij, R. W., El Dib, R., Zhang, Y., ... & Rabassa, M. (2019). Reduction of red and processed meat intake and cancer mortality and incidence: a systematic review and meta-analysis of cohort studies. Annals of Internal Medicine171(10), 711-720.

2.    Jägerstad M, Skog K. Genotoxicity of heat-procseeesd foods.Mutat Res. 2005 Jul 1;574(1-2):156–72.

3.    Kaluza, J., Harris, H., Linden, A., & Wolk, A. (2019). Long-term unprocessed and processed red meat consumption and risk of chronic obstructive pulmonary disease: a prospective cohort study of women. European journal of nutrition58(2), 665-672.

4.    Varraso, R., Dumas, O., Boggs, K. M., Willett, W. C., Speizer, F. E., & Camargo Jr, C. A. (2019). Processed meat intake and risk of chronic obstructive pulmonary disease among middle-aged women. EClinicalMedicine14, 88-95.

5.    Zhong, V. W., Van Horn, L., Greenland, P., Carnethon, M. R., Ning, H., Wilkins, J. T., ... & Allen, N. B. (2020). Associations of processed meat, unprocessed red meat, poultry, or fish intake with incident cardiovascular disease and all-cause mortality. JAMA internal medicine180(4), 503-512.

6.    https://www.cancer.org/latest-news/world-health-organization-says-processed-meat-causes-cancer.html

7.    https://www.eupati.eu/pharmacoepidemiology/risk-factors-health-disease/#Types_of_risk_factors

8.    https://www.nhs.uk/live-well/eat-well/red-meat-and-the-risk-of-bowel-cancer/  

Weblink last accessed 21/05/20

 

 

 

 

 

 

 

 

Sophie Conroy