Building on my previous piece on the dietary prevention of colorectal cancer, I hand the reigns over to my exceptionally competent intern Leeauna Duchesne to explore the topic from a slightly different perspective.
Having previously authored an absolutely brilliant piece on the differential effects of fermented and high fibre foods on the gut microbiome, you guys are in for a real treat today.
Take it away Leeauna!
The Dietary Prevention Of Colon Cancer – Part II
By Leeauna Duchesne
March is colorectal awareness month, and since this disease is becoming increasingly more common (the third most common cancer) -awareness is absolutely needed.
Food, nutrition, digestion and lifestyle factors have strong ties to this type of cancer, and more individuals need to be aware of certain risk factors that could be at play.
I would like to dedicate this article to my uncle John who has been battling colorectal cancer for over a year now.
Why More People Should Care about CRC risks
Colorectal cancer affects the colon and/or rectum, which make up the large bowel and lower digestive tract (World Cancer Research Fund, 2018).
Most people don’t realize that the colon actually has a lot of useful functions. Anything from absorbing water and electrolytes, to producing and absorbing vitamins like calcium, magnesium, potassium, sodium and vitamin K from partially digested food (World Cancer Research Fund, 2018).
The colon and large intestine are also where most of our intestinal microbiota reside. It is fundamental to keep these networks of microbiota alive and healthy in areas like the colon because these microbiota are substantially beneficial to our health (Wastyk et al., 2021).
Did you know that colorectal cancer rates are set to increase by over 60% by the year 2030? This is not just the case for North America either, but for all developed countries. (Loke et al., 2020 ; Sawicki et al., 2021).
This statistic is frankly alarming, but there is good news too. Around 30-50% of most colorectal cancer diagnoses are in fact preventable (World Cancer Research Fund, 2018).
A Look at Modifiable Risk Factors
Modifiable risk factors are factors that are in our individual control (for the most part), such as eating habits, lifestyle and nutrition. These are key areas that need to be targeted in order to reduce the rise in the prevalence of CRC (Sawicki et al., 2021).
For example, a recent study out of the US showed that 38% of all new colon and rectum cancer cases were linked to poor diet; particularly diets low in fibre, vegetables, fruits, wholegrains, dairy, and high in red meat, processed meat and sugar-sweetened beverages (Zhang et al., 2019).
However, what is more concerning than the rapid increase in the prevalence of CRC, is the age of those being diagnosed. There has been a substantial rise in the number of individuals who are being diagnosed with CRC under the age of 50 across many countries (Sawicki et al., 2021).
This is relevant information with possible implications because in Ontario, for example, this type of CRC cancer screening does not become insisted on by health care providers until the age of 50 typically (Canadian Cancer Society, 2021).
Short-Chain Fatty Acids from Food- A Support System:
Short chain fatty acids (SCFA’s) are produced in the colon from the microbiota (aka. bacteria, live microorganisms etc.) in the microbiome. These microbiota metabolically break down complex carbohydrates like dietary fiber, resistant starched and whole grains through a process called fermentation (DeGruttola et al., 2016 ; Wastyk et al., 2021).
A Westernized diet, which lacks these very key nutritional elements that invoke fermentation, is therefore not beneficial to the production of SCFA’s.
The main three SCFA’s produced by intestinal microbiota are named: acetate, propionate, and butyrate (Cheng, Ling & Li, 2020)
These fatty acids are important to physiological and digestive health because they contribute to the integrity and maintenance of the intestines, support the immune system, and also support the health of microbiota in the microbiome (DeGruttola et al., 2016). These SCFA’s are mostly produced within the large intestine (Cheng, Ling & Li, 2020).
In the colon, SCFA’s can also promote epithelial cell proliferation and turnover, a necessary and protective function, which helps to reduce inflammatory markers and keep systemic and chronic inflammation at bay (Wastyk et al., 2021).
How to Increase the Presence of SCFA’s with Food
A diet that includes a variety of fermented foods, bacterial cultures, probiotics and prebiotics (around 2 servings per day), and one that is high in fibre-rich, nutrient-dense foods- is by far the strongest recommendation backed by credible peer reviewed studies (Cheng, Ling & Li, 2020; Sawicki et al., 2021 ; Wastyk et al., 2021).
These 2 elements included in the diet can feed your microbiota, help them survive, and aid in producing SCFA’s to support digestive health.
A Focus on Fibre
Regularly consuming fibrous foods that contain prebiotics, soluble fibre and/or insoluble fibre, has been proven to stimulate the growth of beneficial intestinal microbiota and lead to an increased density of these microbiota (Wastyk et al., 2021).
More than this, a healthy, dense presence of intestinal microbiota will go on to produce more SCFAs that will help them to increase their overall density even more (Sawicki et al., 2021).
These understandings truly explain how and why fibre-rich foods are needed in the diet. Regular fibre intake can substantially reduce the risk of CRC development and plays a key role in the prevention of intestinal/colonic polyps, which are the leading risk factor in CRC formation and tumor growth (Sawicki et al., 2021).
Chronic Inflammation & Colorectal Cancer
Increasing evidence has begun to link dysbiosis of microbiota in the microbiome to the development of certain CRC diagnoses (Cheng, Ling & Li, 2020 ; Sawicki et al., 2021). Dysbiosis of microbiota also happens to be a major contributor to the development of chronic inflammation in the intestines and digestive tract (Cheng, Ling & Li, 2020 ; Sawicki et al., 2021).
In fact, research shows most CRC carcinogenesis (which is abnormal cell growth in the lumen of the colon) begins with the presence of chronic inflammation in the intestines (Sawicki et al., 2021). This is because an inflamed environment within the digestive tract is more susceptible to tears, polyp formation, and abnormal cell growth within its epithelial lining (Sawicki et al., 2021).
The early detection of CRC, more awareness of modifiable risk factors, and a re-focus on changing the Westernized diet, are important opportunities that can reduce the increasing prevalence of CRC (Cheng, Ling & Li, 2020).
Yes, there will always be factors at play that we are not aware of, and circumstances we cannot always control like genetics- and life. But, ultimately going back to the basics of nutrition like avoiding a typical Westernized diet, and re-examining your dietary habits periodically to ensure you are enjoying plenty of fibre-rich and fermented foods, are both evidence-based checkpoints to start with. When in doubt – keep it simple.
Cheers to great health & happy digesting,
Canadian Cancer Society. (2021). Canadian Cancer Statistics Advisory Committee. Canadian Cancer Statistics 2021. Retrieved from: https://cancer.ca/en/cancer-information/cancer-types/colorectal/statistics
Cheng, Y., Ling, Z., & Li, L. (2020). The Intestinal Microbiota and Colorectal Cancer. Frontiers in immunology, 11, 615056. https://doi.org/10.3389/fimmu.2020.615056
DeGruttola, A. K., Low, D., Mizoguchi, A., & Mizoguchi, E. (2016). Current Understanding of Dysbiosis in Disease in Human and Animal Models. Inflammatory bowel diseases, 22(5), 1137–1150. https://doi.org/10.1097/MIB.0000000000000750
Sawicki, T., Ruszkowska, M., Danielewicz, A., Niedźwiedzka, E., Arłukowicz, T., & Przybyłowicz, K. E. (2021). A Review of Colorectal Cancer in Terms of Epidemiology, Risk Factors, Development, Symptoms and Diagnosis. Cancers, 13(9), 2025. https://doi.org/10.3390/cancers13092025
Su, J., Wang, Y., Zhang, X., Ma, M., Xie, Z., Pan, Q., Ma, Z., & Peppelenbosch, M. P. (2021). Remodeling of the gut microbiome during Ramadan-associated intermittent fasting. The American journal of clinical nutrition, 113(5), 1332–1342. https://doi.org/10.1093/ajcn/nqaa388
Wastyk et al., Gut-microbiota-targeted diets modulate human immune status, Cell (2021), https://doi.org/10.1016/j.cell.2021.06.019
World Cancer Research Fund/ American Institute for Cancer Research. Diet, Nutrition, Physical Activity, and Cancer, a Global Perspective. Continuous Update Project Report 2018. Available at dietandcancerreport.org
Zhang, F. F., Cudhea, F., Shan, Z., Michaud, D. S., Imamura, F., Eom, H., Ruan, M., Rehm, C. D., Liu, J., Du, M., Kim, D., Lizewski, L., Wilde, P., & Mozaffarian, D. (2019). Preventable Cancer Burden Associated With Poor Diet in the United States. JNCI cancer spectrum, 3(2), pkz034. https://doi.org/10.1093/jncics/pkz034