Fibre and Bowel Cancer: A Nutritional Therapists Perspective
As a nutritionist, one of the most common questions I get asked is about the role of diet in cancer prevention, particularly bowel (or colorectal) cancer. Among the many dietary factors that can influence the risk of developing this type of cancer, fibre stands out as one of the most significant. Increasing evidence suggests that dietary fibre plays a key role in lowering the risk of bowel cancer. In this article, I’ll discuss how fibre works to protect the bowel, the types of fibre to focus on, and practical tips for increasing fibre intake.
What is Fibre and How Does It Work?
Fibre is the indigestible part of plant foods that passes through the digestive system largely intact. It is found in fruits, vegetables, whole grains, legumes, and nuts. While we often think of fibre as something that helps with digestion and keeps things “moving,” its benefits extend well beyond simple bowel regularity.
There are two main types of dietary fibre:
– Soluble Fibre: This type of fibre dissolves in water to form a gel-like substance. It helps regulate blood sugar and can lower cholesterol levels. Foods high in soluble fibre include oats, beans, lentils, apples, and carrots.
– Insoluble Fibre: This type of fibre does not dissolve in water. It adds bulk to stool and helps move waste through the digestive tract, preventing constipation. Whole grains, seeds, nuts, and vegetables such as cauliflower and green beans are good sources of insoluble fibre.
Both types of fibre are important for gut health, but when it comes to reducing the risk of bowel cancer, insoluble fibre is particularly beneficial.
The Link Between Fibre and Bowel Cancer
Bowel cancer, also known as colorectal cancer, is one of the most common cancers worldwide. The exact cause of bowel cancer is still not fully understood, but it is thought to develop due to a combination of genetic, environmental, and lifestyle factors. Among these factors, diet plays a key role, and fibre intake is one of the most studied.
Mechanisms of Protection
1. Increased Stool Bulk and Faster Transit Time
Insoluble fibre helps to bulk up stools and speed up their passage through the colon. This shorter transit time means the colon is exposed to potentially harmful substances for a shorter period, reducing the risk of damage to cells in the bowel lining. Prolonged exposure to waste products, particularly carcinogenic substances produced during the digestion of red or processed meats, can increase the risk of cancer.
2. Fermentation and Production of Short-Chain Fatty Acids (SCFAs)
When fibre, particularly soluble fibre, reaches the colon, it is fermented by gut bacteria. This fermentation produces short-chain fatty acids (SCFAs) like butyrate, which have anti-inflammatory and anti-cancer properties. Butyrate, in particular, has been shown to promote the health of the cells lining the colon, stimulate cell repair, and even induce cancer cell death in some cases.
3. Improved Gut Microbiota
A high-fibre diet encourages a healthy balance of gut bacteria. A diverse and well-balanced microbiome is thought to play a protective role in reducing inflammation and preventing the development of diseases, including colorectal cancer. Fibre-rich foods support the growth of beneficial bacteria that can outcompete harmful bacteria, reducing the overall risk of gut-related diseases.
4. Detoxification
Fibre helps to bind and remove toxins and carcinogens from the body. In particular, insoluble fibre can bind to bile acids in the colon, reducing the reabsorption of these substances, which have been linked to increased cancer risk when they accumulate over time.
Research on Fibre and Colorectal Cancer
Numerous studies have demonstrated the protective effect of fibre against bowel cancer. According to the World Health Organization (WHO) and the American Institute for Cancer Research (AICR), individuals who consume a high-fibre diet have a significantly lower risk of colorectal cancer compared to those who consume less fibre.
The European Prospective Investigation into Cancer and Nutrition (EPIC) study, which followed over half a million participants, found that each additional 10 grams of fibre consumed per day was associated with a 10-12% reduction in the risk of colorectal cancer. A systematic review published in *The Lancet* also concluded that higher fibre intake, particularly from whole grains, fruits, and vegetables, is inversely associated with the risk of colon cancer.
However, it’s important to note that not all types of fibre have the same impact. The greatest protective effects have been observed from fibre found in whole plant foods, particularly fruits, vegetables, and whole grains, rather than processed or refined fibre supplements.
Practical Tips for Increasing Fibre Intake
If you’re looking to boost your fibre intake and lower your risk of bowel cancer, here are some simple, nutritionist-approved tips:
1. Choose Whole Grains
Switch to whole grain varieties of bread, pasta, rice, and cereal. Foods like quinoa, brown rice, barley, and oats are excellent sources of fibre. Whole grains retain the bran and germ, which contain the bulk of the fibre.
2. Eat More Vegetables and Fruits
Aim for a variety of colourful vegetables and fruits in every meal. Aim for at least five servings a day. Choose fibrous options like broccoli, spinach, carrots, apples, pears, and berries. The skins of fruits and vegetables are rich in fibre, so try to eat them unpeeled where possible.
3. Incorporate Legumes and Pulses
Beans, lentils, chickpeas, and peas are not only high in fibre but also provide a great source of plant-based protein. Try adding them to soups, salads, and casseroles or making bean dips like hummus.
4. Snack on Nuts and Seeds
Almonds, walnuts, chia seeds, and flaxseeds are excellent sources of fibre. Keep a small portion on hand for an easy, fibre-rich snack.
5. Gradually Increase Fibre Intake
If you’re not used to eating a lot of fibre, it’s important to increase your intake gradually to avoid digestive discomfort. Be sure to drink plenty of water to help fibre move smoothly through the digestive system.
6. Limit Processed Foods
Processed and refined foods, such as white bread, sugary snacks, and packaged meals, are low in fibre and can contribute to bowel problems. Opt for whole, unprocessed foods whenever possible.
Conclusion
Fibre plays a critical role in maintaining a healthy bowel and reducing the risk of bowel cancer. By incorporating a variety of fibre-rich foods into your diet, you not only improve digestive health but also help protect yourself from a range of chronic diseases, including colorectal cancer. Whether through soluble or insoluble fibre, the protective benefits are clear, and with small changes to your eating habits, you can significantly lower your cancer risk while enjoying a diverse, balanced diet.
As a nutritionist, I always encourage clients to think of food as medicine. A diet rich in whole foods, especially fibre-rich fruits, vegetables, and whole grains, provides the body with the tools it needs to reduce the risk of disease and promote long-term health.
If you are interested in discussing your nutritional requirements with one of our highly qualified nutritionists then please contact us today or make a booking online.
Article written by Valentina Willats, checked and posted by Steven Hartill.
