Bowel Cancer & Diet #1 - Red Meat & Processed Meat
Most health organisations worldwide advocate against eating a high volume of red meat and processed meats due to their suspected adverse health effects. Yet some people, including social media influencers, encourage increased consumption, especially of unprocessed red meat, which might seem confusing.
This is the first of the Bowel Cancer & Diet mini-blog series, where we will gradually explore different food groups and their suspected link to this disease. This time we are looking at unprocessed red meat and processed meat.
Processed Meat & Bowel Cancer Risk
Processed meat includes salami, ham, bacon, sausages, hot dogs, corn dogs, lunch meat, jerky, ham, and other. These products are usually processed by using preservatives, smoking, curing or salting.
A large 2019 international review of observational studies in ~1.6 million people found that for each 3-serving reduction of processed meat per week (1 serving = 50g portion), the risk of colorectal cancer was reduced by 7%.
A similar finding in a 2020 review of observational research from the USA, Europe, Asia and Australia, found that colon cancer risk in men may be increased even as much as 23%, for every additional 50-gram serving of processed meat per day (equivalent to ½ hot dog). However, this level of risk was not observed in women.
In the most recent 2021 review of 148 articles, people eating the highest quantities of processed meat had an 18% increased risk of colorectal (bowel) cancer and 22% for rectal cancer specifically. They were also more likely to be diagnosed with lung and kidney cancers, potentially due to other unhealthy lifestyle habits such as smoking and drinking alcohol.
What about Unprocessed Red Meat?
One of the polarising aspects of recommendations to reduce intake of red meat (eg. beef, lamb, pork, goat, venison, veal, mutton, pork, duck, goose, boar, elk and bison) is the concern that it provides essential nutrients in the diet. For example, red meat is rich in protein, iron, zinc, phosphorus and specific B vitamins.
But the question remains: does this benefit outweigh the potential risks? One of the issues with much of the available evidence is that researchers group processed and unprocessed red meat together when estimating the risk of bowel cancer.
The European Prospective Investigation into Cancer and Nutrition (EPIC) is one of the world's longest and largest cohort studies. It has been running since 1992 and currently includes 519,978 long-term participants. EPIC aims to assess the dietary and lifestyle factors linked to the development of cancer.
In 2021, EPIC published its most recent results on bowel cancer. They found that each 100-gram daily increment of red meat & processed meat increased the risk of bowel cancer by 55%. Unfortunately, they pooled red & processed together rather than assessed separately, so it is unclear what effect unprocessed red meat alone had on bowel cancer risk.
Fortunately, in a 2021 review of 148 articles, unprocessed red meat was evaluated separately. They found that compared with people eating the least meat, those eating the highest amounts had:
10% ↑ risk of colorectal cancer
17% ↑ risk of colon cancer
22% ↑ risk of rectal cancer
In addition, the women in the 2021 study were at a 9% ↑risk of developing breast cancer and a 25% ↑ risk of endometrial cancer - and even higher for processed meat!
Summary & Key Points
Regular consumption of processed meat such as salami, sausages, hot dogs, jerky and deli meats seems to clearly increase future risk of bowel cancer.
The risk affects both men and women - but might be even higher in men who eat more processed meat specifically.
The amount you eat per day and per week over time matters: the bigger your servings, and the more frequently you consume them, the higher the level of risk.
Reducing your intake appears to lower your risk of developing bowel cancer: smaller servings, eaten less often, reduce the chance of disease.
On the other hand, reducing the weekly intake of these foods has been found to be beneficial overall.
For maximum protection, individual consumption of these foods, especially in processed forms, minimise - and even avoid, where possible.
According to Bowel Cancer UK, weekly red meat consumption should not exceed 500-grams. This amounts to no more than one medium-sized cooked steak 3 times a week.
For those with a family history of bowel cancer or who already had colonic polyps identified upon colonoscopy, even further reduction might be considered.
Let’s stay in touch If you found the information in this mini-blog useful, consider sharing it with someone who might benefit from it. You may also consider following me on social media for more future, similar content.
And if you are struggling with health problems or are keen to take active measure to reduce the odds of future health issues, you might benefit from my nutritional therapy programme. See the first link below.
Farvid MS, Sidahmed E, Spence ND, Mante Angua K, Rosner BA, Barnett JB. Consumption of red meat and processed meat and cancer incidence: a systematic review and meta-analysis of prospective studies. Eur J Epidemiol. 2021 Sep;36(9):937-951.
Han MA, Zeraatkar D, Guyatt GH, et al. . Reduction of Red and Processed Meat Intake and Cancer Mortality and Incidence: A Systematic Review and Meta-analysis of Cohort Studies. Ann Intern Med. 2019 Nov 19;171(10):711-720.
Händel MN, Rohde JF, Jacobsen et al. Processed meat intake and incidence of colorectal cancer: a systematic review and meta-analysis of prospective observational studies. Eur J Clin Nutr. 2020 Aug;74(8):1132-1148.
Ubago-Guisado E, Rodríguez-Barranco M, Ching-López A. Evidence Update on the Relationship between Diet and the Most Common Cancers from the European Prospective Investigation into Cancer and Nutrition (EPIC) Study: A Systematic Review. Nutrients. 2021 Oct 13;13(10):3582.