Bowel cancer

Colorectal cancer also known as bowel cancer, colon cancer or rectal cancer is the second leading cancer cause of death worldwide in 2020. According to the World Health Organisation, 1.93 million new cases of colorectal cancer were reported in 2020, with 935,000 deaths.

Colon cancer begins in the large intestine (colon), where there is growing evidence that the gut microbiome significantly impacts intestinal health and disease. Whether the gut microbiome maintains health or promotes  cancer depends on the composition and balance within the microbial community of protective or harmful bacteria.  Disturbances in the normal balanced state of a healthy microbiome have been detected in colorectal cancer patients. Certain bacterial species have been identified to play a role in colorectal carcinogenesis and are linked by various mechanisms such as genotoxicity (the chemical agents that damage the genetic information within a cell causing mutations), inflammation and oxidative stress.  The symbiotic relationship of these bacteria are influenced by environmental changes, such as infection, diet and lifestyle.

High fat foods (Oils, meat, dairy, eggs, processed, fried and greasy foods) are directly correlated with increased gut bile secretion. This additional bile is needed to break down the fat into smaller components for your body to absorb. The excess bile negatively influences the microbiota composition in the colon which increases the risk of colon cancer.

High-protein, low-carbohydrate diets also negatively influence the bacteria in the microbiome as the high-protein fermentation process generates potentially toxic and pro-carcinogenic metabolites which are involved in the development of colon cancer. These foods include red and processed meats (bacon, sausages, salami, canned meat, ham and deli meats including chicken, turkey, roast beef or pork), dairy products, eggs, chicken and fish.

Continual and/or excessive consumption of alcohol has been found to be an important risk factor in many cancers including colon cancer.  Alcohol is converted in the intestinal tract from ethanol to acetaldehyde which is known to be a highly toxic and pro-carcinogenic compound with various negative effects including DNA damage.

On the plus side, a high fiber diet has been linked to reduced risk of colon cancer. The good bacteria in our gut ferments the carbohydrates from our diet and creates short chain fatty acids. One of these, butyrate, is extremely beneficial and anti-cancer promoting.  So the more fiber rich our diet is, the healthier our gut microbiomes are. High fiber foods are only found in plants and are plentiful in wholefoods such as fruits, vegetables, whole grains and legumes.

Maintaining a healthy weight and enjoying regular exercise have also been found to be effective in decreasing the risk of colon cancer.

My problem with the paleo diet
Michael Klaper M.D.

The answer to a colon cancer mystery
Michael Greger M.D. FACLM

Colorectal Cancer
Physicians Committee for Responsible Medicine

Exercise and Colon Cancer
American College of Sports Medicine

Research papers
The role of the gut microbiome in colorectal cancer

The microbiome and cancer

Gut microbiota imbalance and colorectal cancer

Fiber, fat and colorectal cancer: New insight into modifiable dietary risk factors

Role of dietary fiber in colon cancer: an overview,the%20relationship%20between%20dietary%20fiber%20and%20colon%20cancer.

Body weight gain and risk of colorectal cancer: a systematic review and meta-analysis of observational studies