The following factors decrease the risk of bowel cancer

Modifiable Bowel Cancer Australia Risk Factors

Modifiable Bowel Cancer Australia screening 1152
Polyp removal
People who participate in screening programs reduced their risk of dying from bowel cancer by 16% compared to those who didn't participate in screening. 
Most bowel polyps are adenomas, which may develop into cancer.  Removing bowel polyps that are larger than 1 centimetre (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.  Please note: the possible harms of polyp removal during colonoscopy or sigmoidoscopy include a tear in the wall of the bowel and bleeding. 
Starting step: Participate in screening appropriate to your individual level of risk.  For more information talk to your GP or download Bowel Cancer Australia's Bowel Cancer Risk and Screening brochure.
Fewer than 4 out of every 10 people (38.9%) invited to participate in the tax-payer funded National Bowel Cancer Screening Program actually do. 

Modifiable Bowel Cancer Australia physical activity
Physical activity
Recreational physical activity can reduce colon (not rectal) cancer by 16%.
Starting step: Aim to be physically active where the heart rate is elevated, every day in any way for 30 minutes or more.  As fitness improves, increase the length of time you are active to 60 minutes or engage in more vigorous activity.  Limit sedentary habits such as watching television.
Among 18-24 year-olds, 45% of men and 51% of women are insufficiently active; for those aged 55-64, 54% of men and 60% of women are insufficiently active.  

Modifiable Bowel Cancer Australia wholegrains
Eating 3 servings (a total of 90 grams) of wholegrains a day, such as brown rice or wholemeal bread, can reduce your risk of bowel cancer by 17%.
Starting step: Fill two-thirds or more of your plate with wholegrains, vegetables, fruits, beans and nuts and no more than one-third with animal protein such as poultry or lean red meat.
Only one-third (34%) of all grain (cereal) foods consumed by Australians are wholegrain or high-fibre products.

Modifiable Bowel Cancer Australia calcium
Dairy Products and Calcium Supplements
Dairy products and calcium supplements are associated with a decreased risk of bowel cancer.
Consuming 400 grams of dairy products per day decreases risk by 13%.
Similarly, the consumption of 200 grams of milk or 200mg of dietary calcium per day was associated with a 6% decreased bowel cancer risk.
Starting step: Include dairy products such as low-fat milk, yoghurt, and cheese, in your daily diet. If you are lactose intolerant or need to avoid dairy for other reasons, speak with your GP or a nutritionist about a daily calcium supplement appropriate for you. 
Less than 6% of Australian females aged 19-50 years consume more than 2 serves of dairy or dairy alternatives per day, and only 14% of Australian males in the same age bracket do.
Consumption of dairy and dairy alternatives among Australians aged 51-70 is even less, with around two-thirds of both males and females getting less than 1½ serves per day, and one-third of Australians over age 70 consume less than 1 serve of dairy or dairy alternative daily.

Modifiable Bowel Cancer Australia aspirin
Taking aspirin every day for at least five years decreases the risk of bowel cancer and the risk of dying 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.  
Starting step: Please discuss with your GP.

Nutrition Lifestyle Challenge Bowel Cancer Australia