Dylan Bowe | Last Updated – 30/12/2023 | 4 Minute Read
Fibre has been a hot topic in the nutrition sphere, and for good reason. It impacts our health in profound ways and allows the systems inside of us to operate in a fully functional capacity. Whether you’re a high performance athlete or a casual exerciser, fibre plays a key role in our health, and it is vital to understand what it exactly is, how much we need and where we can get it from in our diet!
What is fibre?
Dietary fibre refers to a complex group of substances in plant foods that can’t be fully broken down by the body and pass through to the colon. In short, it is a type of carbohydrate that our body cannot digest.
Fibre can be split into two categories: soluble and insoluble fibre. Soluble fibre (found in oats, beans, apples) attracts water and turns to a gel-like consistency during digestion, which slows digestion. Insoluble fibre (found in wholegrains and nuts) such as cellulose doesn’t dissolve in water and is difficult to digest, however it adds bulk to the stool, allowing for an easier passage.
How does fibre affect my health?
Fibre affects our health in many ways, and one way it exerts these is by modulating gut health. Most fibres can be defined as prebiotics, which are used to feed the good bacteria in the gut, allowing our gut to strong and become healthier over time. In our large intestine, undigested fibres are fermented by bacteria, which produces short chain fatty acids (SCFA), which include butyrate and acetate. Butyrate is important as it’s the main fuel for cells in the large bowel, and this SCFA along with dietary fibre hold anti-inflammatory properties, as there is some evidence to suggest they may reduce inflammatory biomarkers such as interleukins (Kuo, 2013). SCFA from consuming fibre lowers the pH (more acidic) of the GI tract, which prevents overgrowth of pathogenic bacteria, along with promoting growth of beneficial gut bacteria, and this acidic environment also increases absorption of some minerals such as magnesium and calcium by making them more soluble.
Fibre keeps us fuller for longer, as high fibre foods absorb water and expand, along with taking longer to digest, which leads to a feeling of fullness. There is evidence showing that a healthy fibre consumption is associated with a lower risk of many diseases such as bowel cancer, type 2 diabetes and heart disease. The most obvious effect is decreasing chances of constipation, as previously explained fibre can bulk up stool. Along with this, a high fibre diet may lower the risk of haemorrhoids and colorectal cancer. It can also lead to lower cholesterol (LDL) levels, and one academic review found that diets rich in oats (containing beta glucans) reduced LDL cholesterol by 0.2mmol/L compared to a control diet (Brunner et al., 2005). Fibre can also slow the absorption of sugar and can aid blood sugar regulation after eating a meal, this is known as improving the glycaemic response.
Along with these benefits, the sources of the fibre in our diet usually also contain high amounts of mineral, polyphenols and vitamins, which will all contribute to a healthy and functional body.
How much do I need?
The HSE and Irish Heart Foundation recommend an intake of 25-29g fibre/day for adults, with much of the population not meeting these targets. Only one quarter of adults report they eat 5+ portion of fruit/veg day, while 1 in 5 report they do not eat fruit and vegetables every day! Sources rich in fibre will mainly be fruit, vegetables and wholegrains which includes: whole-wheat pasta and bread, brown rice, apples, oranges, bananas, broccoli, carrots, nuts, beans and legumes.
Tips to increase fibre intake:
- Bulk out with beans: Adding the likes of chickpeas, kidney beans and black beans to your meals will significantly increase your fibre intake. Half a drained tin of these beans will give you anywhere from 8-10g fibre, and if you use them in saucy meals such as a bolognese, soups or stews, you will barely notice them!
- Snack swaps: Where possible, try to replace some of your snacky foods with fruits. A banana contains roughly 2g fibre and will keep you fuller than a lot of on cupboard stored snack bars. A personal favourite of mine is a sliced apple with a serving of peanut butter, this provides lots of micronutrients along with fibre and healthy fats.
- Kick start with breakfast: Breakfast may not be the most important meal of the day, but it can help boost your fibre intake before you even leave the house. Try making overnight oats with yogurt and fruit, a refreshing smoothie packed with frozen berries, or simply some wholegrain toast with nut butter and banana.
- Stock the freezer: It can be difficult to stick to new dietary habits if you find the fridge empty, so it’s a great idea to stock up on frozen fruits and vegetables to add to your meals. It’s a common myth that frozen fruit and veg isn’t as ‘good’ as fresh produce, but they contain the same micronutrient profiles and often are picked and frozen for freshness.
- Swap the starches: swapping white grains for brown grains, such as rice, pasta and bread, is a simple way of increasing your fibre intake without complexity. You can still eat white rice, bread or pasta, but choosing the brown option more often over time will help with your fibre consumption.
References and further reading:
A Healthy Weight for Ireland: Obesity Policy and Action Plan 2016 – 2025
Brunner, E.J., Thorogood, M., Rees, K. and Hewitt, G. (2005) Dietary advice for reducing cardiovascular risk (Cochrane Review). The Cochrane Library, (4).
Kuo, S.M. The interplay between fiber and the intestinal microbiome in the inflammatory response. Adv Nutr (2013), ;4(1):16-28.