The following protective factors decrease the risk of bowel cancer

Polyp removal
Most bowel polyps are adenomas, which may develop into cancer.  Removing bowel polyps that are larger than 1 centimeter (cm) may lower the risk of bowel cancer.  It is not known if removing smaller polyps lowers the risk of bowel cancer.
The removal of polyps means those polyps are unable to become precancerous and develop into bowel cancer in the future.
The possible harms of polyp removal during colonoscopy or sigmoidoscopy include a tear in the wall of the bowel and bleeding.

Physical activity
A lifestyle that includes regular physical activity is linked to a decreased risk of bowel cancer.
Be physically active as part of everyday life.  Greater frequency and intensity produces greater benefits.
Studies show convincing evidence that higher levels of physical activity protect against colon cancer but not rectal cancer.
Healthy Tips

  • Aim for at least 30 minutes every day of brisk walking where heart rate is elevated, then raise to 60 minutes every day.  
  • Limit sedentary habits such as watching television.

Foods Containing Dietary Fibre
Dietary fibre is contained in plant foods.
Data shows convincing evidence that foods containing dietary fibre protect against bowel cancer (10% decreased risk per 10g/day).
There is limited evidence however suggesting non-starchy vegetables (i.e. green, leafy vegetables, broccoli, but not potato etc.) and fruits protect against bowel cancer.
Healthy Tips
Eat at least 5 servings (400g) of a variety of non-starchy vegetables and fruits every day.

  • Eat relatively unprocessed cereals (grains) and/or pulses (legumes) with every meal.

  • Limit refined starchy foods.

  • Non-starchy foods are an important part of a diabetes diet 

Garlic, Milk and Calcium
Studies show garlic, milk (9% decreased risk per 200g/day), and calcium (22% decreased risk for groups with the highest calcium intakes – dietary and supplemental sources) probably protect against bowel cancer.
Healthy Tips

  • The World Health Organisation's (WHO) guidelines for adults is a daily dose of 2-5 grams of fresh garlic (approx. 1 clove); 0.4-1.2g of dried garlic powder; 2-5 mg of garlic oil; 300 to 1,000mg of garlic extract; or other formulations that are equal to 2-5mg of allicin (the active component).
  • 1 cup (250ml ~ 240g) of milk a day.
  • 2½ serves a day of milk alternative with added calcium (100mg per 100ml). 

Taking aspirin every day for at least five years decreases the risk of bowel cancer and the risk of death from bowel cancer.
Please note: the possible harms of aspirin use include a higher than normal risk of bleeding in the stomach, intestines, or brain.  Please discuss with your GP.
Banner Bowel Cancer Australia Helpline
Bowel Cancer Australia Nutrition Lifestyle Challenge
Banner Bowel Cancer Australia Modifiable Risk Factors 300