St Vincents Private Hospitals

Bowel Cancer: Nourishing Your Gut for Better Health

Article by Bonnie Lai- Dietitian Team Leader (June 2025)

Fast facts. Did you know:

• Bowel cancer is the second biggest cancer killer in Australia
• If detected early, bowel cancer can be successfully treated in more than 90% of cases (1)
• Those that have bowel cancer may go on to have surgery to remove some parts of the bowel and may require a modified diet after this surgery
• Your gut contains 30 trillion to 400 trillion micro-organisms/bacteria known as the microbiome and can weigh up to 2kg- the size of a brick! (2)
• There are some modifiable risk factors which can decrease your risk of developing bowel cancer
• Around 50% of Australian adults report they meet the guidelines for adequate fruit intake, and under 8% meet the guidelines for daily vegetable intake (3)

Modifiable dietary risk factors include having adequate fibre in your diet, eating enough non-starchy fruit and vegetables, reducing consumption of alcohol and reducing red meat/processed meat consumption and reducing salt intake. See link Modifiable Risk Factors for Bowel Cancer

Over the last two decades research on the gut microbiome - or your “gut garden” has grown dramatically as an interesting topic for health including research on prebiotics and its health effects.

What are prebiotics? 

Prebiotics are a type of non-digestible fibre that feeds your gut bacteria. We can call this the fertiliser that helps nourish our gut microbes. Food sources of prebiotics are plant foods such as artichokes, asparagus, chicory, bananas, berries, tomatoes, garlic, onions, legumes, green vegetables and wholegrain cereals. What Are Prebiotics? Prebiotics Benefits, Foods, and Downsides

What are probiotics? 

Probiotics introduce new live bacteria into your digestive system and stimulates growth of helpful bacteria. Some studies have reported beneficial effects though most available commercially have not been investigated for effectiveness. Rather it is recommended to focus on eating a whole foods diet rich in prebiotic items and fermented foods. Natural probiotic sources include yoghurt, pickles, miso and sauerkraut.

How much fibre do we need?

Having a good intake of fibre benefits your gut garden by increasing the amounts of beneficial species in your gut. The recommendations for fibre intake for adults are at least 25g for women and 30g for men. (4)

To achieve this recommended amount the Australia Dietary Guidelines recommend you eat: at least 2 serves of fruit each day, at least 5 serves of vegetables (including legumes) each day and a variety of wholegrain or wholemeal foods. For example, one medium apple or pear contains around 5g of fibre and ½ cup of cooked lentils around 8g fibre. High-fibre foods and diet | healthdirect

Some handy hints to increase fibre:

• Fill two-thirds or more of your plate with wholegrains, vegetables, fruits, beans and nuts
• Snack on fibre containing foods: a handful of nuts, a piece of fruit, a slice of wholegrain toast with a nut spread
•  Eat the skin on your fruits and vegetables to get the most fibre out of your food
• Start increasing your fibre intake one meal/snack at a time. Some fibres can cause gas and bloating! So start slowly.
• Drink plenty of water and fluids. Eating enough fibre but not drinking enough water can cause constipation.

Find some simple ways to nourish your gut garden daily! See two links for ideas on food swaps:

CCSA_Fibre_for_a_good_gut.pdf

 easy-swaps-to-boost-your-daily-intake

The information provided is for general informational and educational purposes only and is not a substitute for professional medical advice, diagnosis, or treatment. If you have questions regarding your nutrition, talk to your doctor or Dietitian.

Additional links:

How dietary fibre cuts your cancer risk | Cancer Council

CCSA_Dietary_Fibre_cancer_prevention.pdf

References:

1. Bowel Cancer Australia www.bowelcanceraustralia.org
2. Ferranti EP, Dunbar SB, Dunlop AL, Corwin EJ. 20 things you didn't know about the human gut microbiome. J Cardiovasc Nurs. 2014 Nov-Dec;29(6):479-81. doi: 10.1097/JCN.0000000000000166. 20 Things you Didn’t Know About the Human gut Microbiome - PMC
3. Australian Bureau of Statistics, Dietary Behaviour Dietary behaviour, 2017-18 financial year | Australian Bureau of Statistics
4. Eatforhealth.gov.au, Nutrient Reference Values Dietary fibre | Eat For Health