Dietary fibre: the athlete's discreet ally
NUTRITION
6/22/20256 min read
The health benefits of dietary fibre for the human body
When we talk about sports nutrition, we immediately think of protein for muscles, carbohydrates for energy or electrolytes for hydration. But there's one often-forgotten element that is essential for performance and recovery: dietary fibre. Although it provides neither direct energy nor muscle growth, it plays a fundamental role in digestive health, metabolic balance and keeping your body performing.
In this article, we look at the role of fibre in an athlete's diet, its sources, its effects on performance, and how to include it properly without harming your training.
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What is fibre?
Dietary fibre is a very diverse family of substances: it's the part of plant foods made up of complex mixtures of carbohydrates.
Fibre is a non-digestible carbohydrate that our small intestine can't fully break down or absorb, and it's essential for the large intestine to work properly. So it has no nutritional value as such.
Dietary fibre is made up of non-starch polysaccharides and other plant components such as cellulose, resistant starch, resistant dextrins, inulin, lignins, chitins, pectins, beta-glucans and oligosaccharides.
There are two groups of fibre, depending on their chemical properties and nutritional qualities.
Dietary fibre is divided into soluble and insoluble components. Each category plays a unique role in the health and wellbeing of the human body.
Soluble and insoluble fibre
Soluble fibre
It dissolves in water to form a more or less viscous gel. Its viscosity influences the consistency of the intestinal contents and therefore has digestive and metabolic effects. It can absorb a large amount of water and forms a gel that thickens the stomach contents and slows their passage into the intestine. Soluble fibre is generally quite fermentable; it ferments in the colon and affects both the consistency and frequency of stools.
This fibre, such as pectins, gums or oligosaccharides, is found in fruit and vegetables, pulses, seaweed, potatoes and cereals.
Insoluble fibre
It doesn't dissolve in water but absorbs it, a bit like a sponge, so it swells a lot. It helps you feel full and has a laxative effect. By soaking up water, it increases stool volume and helps regulate bowel function. It ferments little in the colon and acts on digestive contractions through the increased stool volume, so it affects transit.
This fibre, such as cellulose and lignin, is found in cereal products, especially wheat bran, and in leafy vegetables such as spinach or lettuce.
A few figures
Our daily intake is around 20 g for men and 18 g for women, whereas the recommendations ofANSES (the French food safety agency) are 30 g to 45 g per day. In a century, fibre intake has fallen from 30-35 g a day to 15-20 g. Today's diet provides little fibre, which is often removed by industrial processing.
Yet fibre has very beneficial effects on health.
The positive effects of fibre on digestive health
Dietary fibre plays a crucial role in maintaining optimal digestive health. It's generally divided into two categories, soluble and insoluble fibre. Each brings specific benefits, but both contribute to a healthy digestive system.
First, insoluble fibre, found in foods such as wheat bran and vegetables, promotes regular bowel movements. It adds bulk to stools, making them easier to pass through the digestive tract. This not only helps prevent constipation but also reduces the risk of gastrointestinal problems such as haemorrhoids and diverticulitis. According to a study published in the Journal of Nutrition, a higher intake of insoluble fibre is associated with a significant reduction in these conditions.
Soluble fibre, found in foods such as pulses, fruit and oats, plays an essential role in regulating intestinal transit by forming a viscous gel during digestion. This gel slows the absorption of nutrients and helps control blood sugar levels, contributing to smooth digestion. These fibres also act as prebiotics, feeding the gut microbiota. Their presence is associated with a greater diversity of beneficial bacteria in our gut, which is fundamental for overall health. Research has shown that people who eat an ideal amount of soluble fibre have an optimal microbial balance, reducing the risk of digestive diseases.
In summary, eating enough dietary fibre is a key element of digestive health. Whether it's preventing constipation or promoting a healthy microbiota, the benefits of fibre for the gut are many and backed by numerous scientific studies.
The impact of fibre on disease prevention
Fibre is exceptional for the health of the human body but also for athletic performance. A diet rich in dietary fibre plays a crucial role in preventing various chronic diseases. In particular, research shows that fibre can reduce the risk of heart disease, type 2 diabetes and some types of cancer. The biological mechanisms behind these protective effects are varied and include factors such as regulating metabolism and improving gut health.
1. Blood sugar control that supports endurance and limits diabetes
Viscous soluble fibre slows down the digestion of carbohydrates, so glucose is absorbed more slowly into the blood. It therefore helps keep blood glucose levels more stable. Resistant starch, for its part, increases insulin sensitivity. In the long term, a high-fibre diet is an excellent way to avoid high blood sugar and the onset of type 2 diabetes.
Result: fewer insulin spikes, more consistent energy, and fewer cravings or energy dips during long sessions or competitions.
2. A digestive system in top shape to perform better and fight constipation
A healthy gut is the foundation of good nutrient absorption. Fibre feeds the gut microbiota, which influences not only digestion but also immunity, recovery and even mood. A healthy microbiota can support better absorption of amino acids and minerals, which are essential for performance and muscle repair.
Soluble or insoluble, fibre has a positive effect on intestinal transit. By swelling with water, it increases the weight and volume of the food mass, keeping transit time healthy and making it easier to pass.
Dietary fibre stimulates intestinal peristalsis, in other words the movement of food through the intestines. Fibre holds on to water (from drinks) all the way into the intestine (keeping stools hydrated). This means fibre lets stools move through your body before they have a chance to become hard, dry and difficult to pass.
3. Protecting against some digestive cancers
In the digestive tract, fibre swells and traps certain molecules from food so they're eliminated in the stools. Fibre also limits the contact time between the intestinal lining and toxins (pesticides, food additives, alcohol, etc.).
Fibre therefore reduces the risk of colon cancer, because the digestive tract is less exposed to toxins. As a result, it's recommended to include a variety of high-fibre foods in your daily diet to get the most health benefits.
4. Lowering cholesterol
Viscous soluble fibre helps lower LDL ("bad") cholesterol in the blood, playing a role in preventing cardiovascular disease.
Fibre traps fat molecules, including cholesterol. Some of the cholesterol is therefore eliminated in the stools, and the body uses its own cholesterol to make new bile salts and keep digestion working well.
5. Keeping you full
By swelling in the digestive tract, fibre considerably increases the volume of the stomach contents and slows digestion. It supports healthy weight management by prolonging the feeling of fullness, limiting cravings, and gives better control over food intake.
High-fibre foods also need more chewing, and chewing plays an essential role in satiety: it stimulates various receptors (tongue, teeth, palateâŠ) that tell the brain we are eating and receiving nutrients.
How much fibre should you eat?
The general recommendation is 25 to 35 g of fibre per day for an adult. But for athletes, needs can vary depending on:
Training volume
How much you sweat
The type of sport (endurance, strength, mixed)
To optimise performance without digestive discomfort, it's advisable to increase your fibre intake gradually, especially if you don't eat much at the moment.
Increasing your fibre intake is essential to get the full health benefits. To start, gradually introduce high-fibre foods into your daily diet. For example, choose whole grains such as wholemeal bread, brown rice or wholewheat pasta. They generally contain more fibre than their refined equivalents.
Adding pulses such as lentils, chickpeas and beans can also increase your fibre intake. These foods are not only nutritious but also versatile: you can add them to salads and soups, or include them in main dishes for a rich, satisfying texture.
Fruit and vegetables are another invaluable source of dietary fibre. Eat fruit such as pears, raspberries and apples, known for their high fibre content. Likewise, cruciferous vegetables such as broccoli and cauliflower or leafy greens such as spinach provide plenty of fibre. Consider making smoothies, where you can blend a variety of fruit and vegetables into a nutritious drink.
To avoid the digestive discomfort that can result from increasing fibre too quickly, increase the amount in your diet slowly. This gives your digestive system time to adapt without causing discomfort. At the same time, remember to drink at least 2 litres of water a day to help the fibre do its job and make digestion easier.
Be careful with digestion before exercise
Fibre is beneficial, but not always training's best friend in the short term. Eating a very high-fibre meal just before an intense session can cause bloating, cramps or digestive discomfort.
Practical tips :
Avoid fibre in the 2 to 3 hours before intense exercise.
Favour fibre at breakfast on rest days, or at dinner.
During competition periods, slightly reduce your fibre intake in the 24-48 hours before an event to avoid digestive problems.
In summary: fibre, the smart athlete's hidden asset
Fibre may not be the most glamorous nutrient, but it is a pillar of lasting performance. It strengthens digestive health, supports faster recovery, improves blood sugar control and helps optimise body composition. For an athlete, ignoring fibre is like skipping the warm-up: you can get away with it for a while, but eventually you pay the price.
Include it intelligently, adapt your intake to your training, and you'll see a real difference in the long run. A happy gut means a stronger athlete!
