Colorectal cancer is the third most commonly occurring cancer in men, the second most commonly occurring cancer in women, and the fourth leading cause of cancer deaths world-wide. It is the most common in westernised countries, such as Ireland and the UK (1).
There were over 1.8 million new cases in 2018. Over the next 15 years, the number of cases of colorectal cancer are expected to increase by 60% to more than 2.2 million. There are numerous lifestyle factors that can increase the risk of developing colorectal cancer such as a high Body Mass Index (BMI), level of physical activity, smoking, and diet (2). However, there are things you can do that might help lower your risk, but there's no way to completely prevent cancer.
One of the factors that may help reduce your risk of developing colorectal cancer is fibre. Fibre is thought to reduce the risk of developing this type of cancer because of its effect on the digestive system. As discussed in previous posts, fibre is a type of carbohydrate that the body cannot easily break down during digestion, and because we cannot break it down, it passes through our gut into our large intestine. This movement of fibre through our digestive system is extremely important to maintain good gut health and regular bowel movements (3).
The British Medical Journal carried out a large scale review of over 25 different studies to investigate the relationship between fibre and colorectal cancer. They reported that a high intake of fibre, specifically fibre from cereal fibres and wholegrains, are associated with a lower risk of colorectal cancer. They reported that for every 10g intake of fibre daily (from cereal fibre) there was an associated 10% reduction in the risk of colorectal cancer. They also noted that there was approximately a 20% reduction for each three servings (90g/day) of whole grains consumed daily. This study did note that there is more research needed in this area, but the current evidence is very promising (4). Another large scale study also found a decreased risk in developing colorectal cancer with increased fibre intakes. This study estimated that the risk of colorectal cancer could be reduced by nearly 31% if people increased their fibre intake by 13g/d (5).
There is a vast amount of information currently available on this topic. The most important point to take from this post is that although fibre may reduce the risk of developing colorectal cancer, it does not solely prevent it. The overall adherence to a healthy diet and lifestyle, one that includes physical activity, is the best way to ensure a long and healthy life.