How to Lower Your Risk for Colorectal Cancer: Part 1

Colorectal cancer (CRC) is the third most common cancer diagnosis.  While the rate of CRC in people over the age of 55 has been declining since the 1980s, adults 20 to 39 years of age are seeing their rate increasing by about 1 to 2.4% every year.  Worryingly, those born around 1990 have almost double the risk for CRC of those born around 1950. For men under 50, CRC is now the leading cause of cancer-related death.  In women under 50, CRC is now the second leading cause of cancer death.  (1,2,3)

 

What could be causing this rise in CRC in young people? 

The director of the Cleveland Clinic Center for Young-Onset Colorectal Cancer in Cleveland, Ohio, states that so far there are many theories but no clear-cut answers.  While there are a few genetic traits associated with familial CRC, the vast majority, approximately 70%, of CRC cases are not genetic in origin.  Rising rates of obesity; low levels of physical activity; poor dietary choices such as lack of fiber from not eating enough fruits and vegetables, consuming too much red meat and high-fat and processed foods; smoking; and alcohol consumption are all related to increased risk of CRC.  However, many young people with CRC don’t fit into these categories as they are often in good shape and already eating very healthfully.  Research is turning to the investigation of whether certain microbes in the gut may be contributing to the growth of tumors in the intestines.  (3,4)

In September of 2024, a think tank organized by the National Cancer Institute (NCI) and the National Institute of Environmental Health Sciences (NIEHS) in the US brought together more than 400 leading scientists and patient advocates to exchange ideas and information about CRC in younger adults.  The group noted that some of the issues that raise the risk of CRC in older adults have become more common over the last 45 years and may be responsible for the rise of early-onset disease.  But they also theorized that there may be a unique set of risk factors in younger adults that amplify their risks.  Such risk factors have not yet been identified.  Nonetheless, what is clearly understood is that, when the incidence of a disease changes from one generation to another, the culprit is likely something in the environment.  (5)

A variety of ways of eating unhealthfully definitely have become more accepted in recent decades and the evidence linking the consumption of detrimental foods to early-onset CRC is increasing too.  At the very least, foods like processed meats, red meats and processed foods cause inflammation which is itself associated to increased risk of CRC. Recent studies illustrate that half of the younger adults with CRC are overweight and 17% are obese.  Half of younger adults with CRC are also suffering from other chronic diseases such as irritable bowel syndrome, Crohn’s disease and diabetes, all conditions that can raise inflammation in the gut.  (5)

Other elements that may be potential causes of early-onset CRC are pesticides; chemicals that end up in the soil; and air and water pollution which may be exerting their effects directly on growing tumours or indirectly via the microbes living in the gut.   (5)

New avenues of investigation about the possible causes of young-onset CRC are exploring the effects initiated by the microbes that live in our gut microbiomes.  The amount of diversity among the bacterial species living there may be an important aspect of a possible link between gut microbes and the onset of CRC.  It is not surprising that our gut bugs are affected by the food we eat and the chemicals with which we come into contact.  Indeed, changes in the gut microbiome appear to be influencing the increasing incidence of CRC in young adults. Certain harmful types of gut bacteria are related to faster growth of CRC. Others produce toxins that trigger inflammation which is an accelerator of tumour growth on its own. Some gut bacteria can even affect how well cancer treatments work.  Amidst all the variations in species in each individual gut microbiome, there may be an optimal level of certain healthy bacterial species and food choices may be one key to achieving the ideal mix of gut microbes that leads to vibrant health.  (3,5)

 

What risks for CRC can be modified by our own actions through altering the environment around and within us?  

Eating an Unhealthy Diet

We know that there is a close relationship between CRC and the foods that we choose to eat.  Our body weight can also influence our risk of CRC.  This is hopeful news because, right off the bat, here are two modifiable factors that can be influenced by our own lifestyle to reduce the risk of developing CRC. (1)

A study from 2021 demonstrated that women who drank more than two sugary drinks a day had more than double the risk of early-onset CRC compared with women drinking less than one sugary drink a day.  (6)

In addition, recurrences of CRC are twice as likely in those eating foods that increase insulin levels (white bread, sugar-sweetened drinks and processed snacks) compared with those who consume the least amounts of these foods (6).

Another study from late 2024 discovered that people who eat an abundance of fresh and minimally processed foods are less likely to develop CRC compared to people who consume a lot of ultra-processed foods including ready-to-eat meals, processed meats, sweets and carbonated soft drinks. (6)

The colon and rectum are particularly sensitive to dietary influences.  Study reviews demonstrate that eating red and processed meat is linked to higher risk of CRC by as much as 10 to 16% for each 100 grams/day increase in the consumption of red meat and by 16 to 22% for each 50 grams/day increase in the consumption of processed meats.  (1,2)

Red and processed meats are considered carcinogenic to the human body by the International Agency for Research on Cancer.  There are many elements in red and processed meats that may influence the development of cancers.  For example, red meats contain heme, a ring-shaped constituent of hemoglobin that includes an iron component which can damage the lining of the colon, leading to CRC (23).  Red meat can also affect the microbiome by increasing the growth of unhealthy microbes causing chronic inflammation which is associated with cancer.  Smoking or grilling meat at high temperatures produces HCAs (heterocyclic amines) and PAHs (polycyclic aromatic hydrocarbons) that are known to cause cancer.  Processing of meats (bacon, deli meats and sausage) results in the addition of nitrates and nitrites into the meat during their processing.  These two chemicals are both linked to higher risks of many kinds of cancer including CRC.  White meats (lean pork and poultry) are not related to increased CRC risk.  (1,2)

 

Being Overweight

People who are overweight or obese have higher levels of insulin in their bloodstream.  Excess fat tissue responds more slowly to insulin and thus allows blood insulin levels to rise.  High insulin levels encourage many types of cancer to grow.  Studies illustrate that a loss of just 10% of body weight is linked to lower insulin blood levels. (1)

 

Lacking in physical activity

Research illustrates that a sedentary lifestyle (spending much of the day sitting without whole body movement) augments the risk of CRC.  Unfortunately, our way of life has altered immensely over the last couple of generations.  From daily physical labour to daily sitting in front of a screen is a huge change for our bodies.  Additionally, if 80% of a person’s day is spent sitting, even doing the recommended amount of daily physical activity cannot overcome the negative effects of the prolonged sitting.  Studies reveal that high energy movement during both work time and leisure time is needed to decrease the risk of CRC.  (2)

 

Smoking

Tobacco is another established risk factor for CRC with both previous and current cigarette smoking associated with a rise in risk.  Carcinogens in cigarette smoke include both PAHs and HCAs as well as other chemicals which can cause mutations that lead to the development of cancer.  Compared to those who have never smoked, there is a 15% increased risk of death from CRC in former smokers and a 40% increased risk of death in current smokers.  Increasing cigarette smoking by 1 pack (20 cigarettes) per day worsens the risk and the mortality of CRC by a further 17% in former smokers and by 40% in current smokers.  (2)

 

Drinking alcohol

Alcoholic beverages are known to escalate the risk for a variety of cancers including CRC.  It has been established that for each increase in the total number of alcoholic drinks per day, CRC risk grows by 6%.  (One drink is defined as 10 grams of alcohol.)  The risk for moderate drinking (2 to 3 alcoholic drinks per day) is associated with an increased CRC risk of 21 to 25%.  This makes alcohol a strong risk factor for CRC.  (1,2)

Read Part 2 of this blog to learn ways in which we can protect ourselves against CRC.

 

 

SOURCES:

https://connect.mayoclinic.org/blog/cancer-education-center/newsfeed-post/the-relationship-between-nutrition-and-colon-cancer

https://www.ncbi.nlm.nih.gov/books/NBK585999/

https://www.cbc.ca/news/health/colorectal-cancer-keeps-rising-among-younger-adults-no-one-s-sure-why-1.6772096

4  https://health.clevelandclinic.org/colon-cancer-in-young-adults

https://www.cancer.gov/news-events/cancer-currents-blog/2020/colorectal-cancer-rising-younger-adults

https://www.npr.org/sections/health-shots/2023/03/20/1163697875/colon-cancer-signs-screening-young-adult

7  Xiong, R.G., Zhou, D.D., Wu, S.X., Huang, S.Y., Saimaiti, A., Yang, Z.J., Shang, A., Zhao, C.N., Gan, R.Y., Li, H.B. Health Benefits and Side Effects of Short-Chain Fatty Acids. Foods. 2022 Sep 15;11(18):2863. Doi: 10.3390/foods11182863. PMID: 36140990; PMCID: PMC9498509.

8  Tuohy, K.M., Gougoulias,C., Shen, Q., Walton, G., Fava, F., Ramnani, P. Studying the human gut microbiota in the trans-omics era–focus on metagenomics and metabonomics. Curr Pharm Des. 2009;15(13):1415-27. Doi: 10.2174/138161209788168182. PMID: 19442166.

https://www.ccsa.ca/canadas-guidance-alcohol-and-health

10  Bradbury ,K.E., Murphy, N., Key, T.J. Diet and colorectal cancer in UK Biobank: a prospective study. Int J Epidemiol. Published online April 17, 2019.

11  Obón-Santacana, M., Romaguera, ,D., Gracia-Lavedan, E., et al. Dietary inflammatory index, dietary non-enzymatic antioxidant capacity, and colorectal and breast cancer risk (MCC-Spain Study). Nutrients. 2019;11:1406-1426.

12  Ocvirk, S., Wilson, A.S., Appolonia, C.N., Thomas, T.K., O’Keefe, S.J.D. Fiber, Fat, and Colorectal Cancer: New Insight into Modifiable Dietary Risk Factors. Curr Gastroenterol Rep. 2019;21:62-69.

13  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;36(9):937-951. doi:10.1007/s10654-021-00741-9

14  Huang Y, Cao D, Chen Z, et al. Red and processed meat consumption and cancer outcomes: Umbrella review. Food Chem. 2021;356:129697. doi:10.1016/j.foodchem.2021.129697

15  Kim, J., Boushey, C.J., Wilkens, L.R., Haiman, C.A., Le Marchand, L., Park, S.Y. Plant-based dietary patterns defined by a priori indices and colorectal cancer risk by sex and race/ethnicity: the Multiethnic Cohort Study. BMC Med. 2022;20(1):430-444. Doi:10.1186/s12916-022-02623-7.

16  Abd Rashid, A., Ashari, L., Shafiee, N., et al. Dietary patterns associated with colorectal cancer risk in the Malaysian population: a case-control study with exploratory factor and regression analysis. BMC Public Health. 2023;23:1386. Doi:10.1186/s12889-023-16283-6.

17  Wu, B., Zhou, R., Ou, Q., Chen, Y., Fang, Y., Zhang, C. Association of plant-based dietary patterns with the risk of colorectal cancer: a large-scale case-control study. Food Funct. 2022;13:10790-10801. Doi:10.1039/d2fo01745h.

18 Yu, Y.C., Paragomi, P., Jin, A., Wang, R., Schoen, R.E., Koh, W.P., Yuan, J.M., Luu, H.N. Low-Carbohydrate Diet Score and the Risk of Colorectal Cancer: Findings from the Singapore Chinese Health Study. Cancer Epidemiol Biomarkers Prev. 2023 Jun 1;32(6):802-808. Doi: 10.1158/1055-9965.EPI-22-0683.

19 Tammi, R., Kaartinen, N.E., Harald, K., et al. Partial substitution of red meat or processed meat with plant-based foods and the risk of colorectal cancer. Eur J Epidemiol. Published online January 23, 2024. Doi:10.1007/s10654-024-01096-7

20  Wang, K., Lo, C.H., Mehta, R.S., Nguyen, L.H., Wang, Y. et al.  An Empirical Dietary Pattern Associated With the Gut Microbial Features in Relation to Colorectal Cancer Risk. Gastroenterology. 2024 Dec;167(7):1371-1383.e4. Doi: 10.1053/j.gastro.2024.07.040. Epub 2024 Aug 6. PMID: 39117122; PMCID: PMC11581916.

21  Soundararajan, R., Maurin, M.M., Rodriguez-Silva, J., et al   Integration of lipidomics with targeted, single cell, and spatial transcriptomics defines an unresolved pro-inflammatory state in colon cancer.  Gut.  Published Online First: 10 December 2024. Doi: 10.1136/gutjnl-2024-332535

22  https://www.newsweek.com/doctors-colon-cancer-rise-gen-z-millennials-1986245

23 Genua, F., Raghunathan, V., Jenab, M., Gallagher, W.M., Hughes, D.J. The Role of Gut Barrier Dysfunction and Microbiome Dysbiosis in Colorectal Cancer Development. Front Oncol. 2021 Apr 15;11:626349. Doi: 10.3389/fonc.2021.626349. PMID: 33937029; PMCID: PMC8082020.

24  O’Keefe, S.J.D. Plant-based foods and the microbiome in the preservation of health and prevention of disease. Am J Clin Nutr. 2019 Aug 1;110(2):265-266. Doi: 10.1093/ajcn/nqz127. PMID: 31268135; PMCID: PMC6669048.

25  https://www.canada.ca/en/health-canada/services/nutrients/fibre.html

 

 

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My name is Debra Harley (BScPhm) and I welcome you to my retirement project, this website. Over the course of a life many lessons are learned, altering deeply-rooted ideas and creating new passions.

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