Alcohol | Aspirin | Body fatness | Dairy | Physical activity | Polyp removal | Red & processed meat | Smoking | Wholegrains
Diet and lifestyle choices, as well as screening and surveillance, can influence your bowel cancer risk.
Because these are things you can change (modify), they are referred to as 'modifiable' risk factors.
US research (published 2021) indicates up to 34% of bowel cancer cases may be prevented by a healthy lifestyle,* increasing to 61% when combined with sigmoidoscopy / colonoscopy screening.
Having one or more risk factors does not always mean that you will get bowel cancer, and some people who are diagnosed with bowel cancer may not have any known risk factors.
*A healthy lifestyle is defined as these five factors: normal body weight; never smoking or past smoking with pack-years <5; moderate-to-vigorous intensity activity for ≥30 minutes per day; none-to-moderate alcohol intake; and meeting at least 3 of the 6 dietary recommendations by the World Cancer Research Fund (WCRF) Third Expert Report 2018, which included red meat <0.5 serving/d, processed meat <0.2 serving/d, dietary fibre ≥30 g/d, dairy products ≥3 servings/ d, whole grains ≥48 g/d or account for at least half of total grains, and calcium supplement use.
Bowel cancer risk increases significantly when two or more alcoholic drinks are consumed per day.
If you choose to drink alcohol, limit the amount.
In 2017–18, 16.1% of people aged 18 and over consumed (on average) more than 2 standard drinks per day - exceeding the lifetime risk guideline. This is down from 20.9% in 2007–08. (AIHW 2020).
Taking aspirin every day for at least 5 years decreases the risk of developing bowel cancer as well as 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.
Please discuss with your GP before taking aspirin.
| Body fatness
Bowel cancer risk rises with increased body fatness, as marked by body mass index (BMI), waist circumference or waist-hip ratio.
During childhood and adolescence, be as lean as possible within the normal range of body weight. From age 21, maintain body weight within the normal body mass index (BMI) range.
Throughout adulthood, avoid weight gain and increases in waist circumference.
In 2017–18, 66.4% of people aged 18 and over were overweight or obese (age-standardised rate). This is up from 61.1% in 2007–08. (AIHW 2020).
| 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 15%. Similarly, the consumption of 200 grams of milk or 200mg of dietary calcium per day was associated with a 6% decreased bowel cancer risk. 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.
| Physical activity
Recreational physical activity can reduce colon (not rectal) cancer by 16%.
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.
In 2017-18, 46% of men and 55% of women aged 18 to 64 did not meet the physical activity guideline - to be active on most, preferably all days with at least 150 minutes of moderate to vigorous activity per week (AIHW 2020).
| Polyp removal
People with cancers diagnosed through the National Bowel Cancer Screening Program had a 40% lower risk of dying than people who had not been screened.
Most bowel polyps are adenomas, which may develop into bowel 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.
Participate in screening appropriate to your personal level of risk.
Only 41.6% of people invited to participate in the tax-payer funded National Bowel Cancer Screening Program actually do.
| Red and processed meat
Eating too much red meat (e.g. beef, lamb, pork, goat) has been linked with an increased risk of bowel cancer.
Eating processed meats such as bacon, ham, salami and some sausages has been strongly linked with an increased risk of bowel cancer.
If you eat red meat, limit the amount to no more than about three portions per week. Three portions is equivalent to about 350-500 grams cooked weight.
When barbecuing, partly cook meat in the oven first to reduce cooking times on open flames or grills. Keep temperatures low and use marinades to protect meat from burning.
Eat very little, if any, processed meat.
Australians aged 19 years and over consume an estimated average of 560 grams of red meat per week.
Smoking 40 cigarettes (two packs) per day increases the risk of bowel cancer by around 40% and nearly doubles the risk of bowel cancer death.
Quit smoking and avoid exposure to tobacco smoke.
In 2017–18, 13.8% of people aged 18 and over were daily smokers. This was down from 18.9% in 2007–08, but has remained relatively stable since 2014–15, at around 14%. (AIHW 2020).
| Wholegrains and dietary fibre
Consuming wholegrains and foods containing dietary fibre decreases the risk of bowel cancer.
Eating at least 90 grams of wholegrains a day, such as brown rice or wholemeal bread, can reduce the risk of bowel cancer by 17%.
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.