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With fast and ultra-processed foods everywhere, many people have a diet that is deficient in fibre, meaning that they miss out on all its wonderful benefits.

Fibre plays an important role in maintaining our health and well-being. From digestion to disease prevention, fibre provides us with many benefits. Let’s explore just how good fibre is for us, how it delivers its benefits, and what happens when we have too much or too little fibre in our diet.

What is fibre? 

Fibre, loosely defined, is a type of carbohydrate that our bodies cannot digest. Other carbohydrates like sugars and starches are broken down and absorbed into our bloodstream. Not so with fibre; it passes relatively intact through the digestive system. That, surprisingly, is what gives fibre its unique health benefits. Let’s digest specifically how.

The benefits of fibre 

• Blood sugar control benefits. Soluble fibre slows down the absorption of sugar from the digestive tract, preventing spikes in blood glucose levels after meals. This is particularly important for people with diabetes or insulin resistance, as it helps manage blood sugar levels and reduce the risk of complications from diabetes.
• Digestive health benefits. Fibre has a positive impact on digestion by adding bulk to stool, making it easier to pass and preventing constipation. It also helps regulate bowel movements and can alleviate symptoms of irritable bowel syndrome (IBS) in some individuals.
• Gut health benefits. Fibre acts as a prebiotic, feeding beneficial bacteria in the gut. A healthy gut microbiome is essential for digestion, nutrient absorption, immune system strength, and overall well-being.
• Cholesterol benefits. Soluble fibre binds to cholesterol in the digestive tract, preventing its absorption into the bloodstream. This helps lower LDL (“bad”) cholesterol levels and reduces the risk of heart disease, which is one of the leading causes of death worldwide.
• Weight management benefits. Fibre-rich foods are more filling than low-fibre foods and add bulk to the diet without many calories, helping with weight management. Additionally, fibre’s slower digestion helps stabilise blood sugar levels, preventing energy crashes that lead to cravings and overeating.
• Disease prevention benefits. A high-fibre diet has been linked to a reduced risk of several chronic diseases, including type 2 diabetes, heart disease, certain cancers (especially colorectal cancer), and diverticular disease.

How does fibre work its magic?

While the exact mechanisms by which fibre protects against disease are not fully understood, its benefits are known to affect gut health, blood sugar control, cholesterol levels, and inflammation. Fibre’s positive effects appear to result from its unique properties and how it interacts with the digestive system.

There are two main types of fibre: soluble and insoluble.

Soluble fibre dissolves in water to form a gel-like substance. It is found in foods such as oats, barley, apples, and beans. Soluble fibre is particularly effective at lowering cholesterol and regulating blood sugar levels. Additionally, it acts as a prebiotic, helping to nourish beneficial bacteria in the gut.

Insoluble fibre does not dissolve in water and adds bulk to stool. It is found in foods like whole wheat bread, bran, and vegetables. Insoluble fibre helps promote regular bowel movements and prevents constipation.

What are the sources of healthy fibre?

Many tasty and readily available foods are excellent sources of fibre. Here are some.

• Fruits and vegetables. Most fruits and vegetables contain fibre, with some being particularly rich in it, such as berries, apples, pears, broccoli, carrots, and leafy greens. Whenever possible, eating the skin of fruit and vegetables is beneficial, as it often contains a high amount of fibre.
• Whole grains. Whole grains are a strong source of fibre. Examples include whole wheat bread, brown rice, quinoa, and oats. Products that list whole grains as the first ingredient tend to be high in fibre.
• Legumes. Beans, lentils, and peas are packed with fibre and protein, along with other essential nutrients. They are a versatile and affordable way to add fibre to your diet.
• Nuts and seeds. Nuts and seeds are a good source of fibre and healthy fats. Examples include almonds, walnuts, pistachios, hazelnuts, brazil nuts, cashews, pecans, chia seeds, flax seeds, sunflower seeds, sesame seeds, hemp seeds, and poppy seeds.

The consequences of too much fibre

Consuming too much fibre can cause unpleasant side effects, especially if we increase our intake too quickly or don’t drink enough fluids. Here are the effects to expect:

• Digestive issues. Too much fibre can cause bloating, gas (excessive farting), cramping, loose bowels, or even diarrhoea. This happens when undigested fibre ferments in the gut, producing gas.
• Nutrient absorption. In very high amounts, fibre can interfere with the absorption of certain minerals, such as iron, calcium, and zinc. This is more likely to occur in people with marginal nutrient status (those consuming less than the recommended daily amount).
• Immune system. Fibre plays a crucial role in supporting a healthy gut microbiome, which in turn strengthens the immune system and helps protect against infections and diseases.
• Energy levels. Fibre stabilises blood sugar levels, helping to avoid energy peaks and troughs, which leads to more consistent energy levels throughout the day.
• Hormone regulation. Some studies suggest fibre plays a role in regulating hormones, potentially helping with conditions such as premenstrual syndrome (PMS).

Takeaway

Numerous studies have shown a link between high fibre intake and a reduced risk of certain cancers, particularly colorectal cancer. While the exact mechanisms by which fibre protects against cancer are still not fully understood, factors such as its effect on gut health, its ability to bind to carcinogens, and its influence on inflammation are likely involved.

The recommended daily intake of fibre is 25-30 grams for adults, but most people consume far less, resulting in known negative health consequences.

If you decide to increase your fibre intake, it’s wise to do so gradually to avoid digestive discomfort. Drinking plenty of water is also essential, as it helps prevent constipation.

Fibre plays a major role in maintaining health and preventing disease. By incorporating a variety of fibre-rich foods into your diet, you can unlock benefits ranging from improved digestion and blood sugar control to a reduced risk of chronic diseases.

Professor Nigel MacLennan runs the performance coaching practice PsyPerform.