The Essential Role of Fibre in Health
When people think about healthy eating, the focus often falls on protein, carbs, and fats, but there’s little focus on dietary fibre (also known as “non starchy polysaccharides [NSPs]”, which is a quiet hero in our health playing an essential role in many ways. Fibre is a type of carbohydrate that your body can’t digest, yet it plays a vital role in supporting your gut, heart, and overall wellbeing, so here, I’m describing why it matters, and how you can easily add more to your diet.
What Is Dietary Fibre?
Dietary fibre refers to the indigestible parts of plant foods, such as fruits, vegetables, grains, legumes, nuts, and seeds. Unlike other carbohydrates that are broken down into sugar, fibre passes through the digestive system (the gut) mostly intact, performing a variety of beneficial functions along the way. There are two main types of fibre , both of which are important:
1. Soluble Fibre
Dissolves in water to form a gel-like substance.
Helps slow digestion and stabilise blood sugar levels.
Can help lower LDL (“bad”) cholesterol.
Sources include: oats, beans, lentils, apples, citrus fruits, flaxseeds, and psyllium husk.
2. Insoluble Fibre
Adds bulk to your stool and helps food move through your digestive tract.
Prevents constipation and supports regular bowel movements.
Sources include: whole grains, bran, nuts, seeds, and the skins of fruits and vegetables.
The Health Benefits of Fibre
1. Supports Digestive Health (perhaps the most known or discussed role).
You may have heard the terms “gut microbiome, “gut microbiota” or “gut biota”, which refer to the colonies of millions of bacteria that live in your digestive system, and play a vital role in health, and you’ve probably even seen many food labelled as “prebiotic”. Fibre feeds the beneficial bacteria in your gut, helping to maintain a balanced gut microbiome.
Fibre is ferments by the gut bacteria, producing short-chain fatty acids (SCFAs) such as acetate, propionate, and butyrate. SCFAs provide several health benefits: they supply up to 10% of the body’s daily energy needs, nourish cells in the colon (large intestine), enhance water absorption in the colon, and support the barrier between the intestine and the rest of the body thus protecting against harmful substances. They also support gut motility (movement of food through the digestive system), and inhibit the growth of haermful bacteria. However there are several factors that can alter the gut microbiome.
SCFAs influence weight management by helping regulate metabolism. They enhance insulin sensitivity, promote fat oxidation, reduce fat storage (especially visceral fat), and stimulate thermogenesis inside fat cells (the burning of fat). Additionally, SCFAs stimulate the release of satiety hormones such as peptide YY (PYY) and glucagon-like peptide-1 (GLP-1), which help suppress appetite (Chambers et al., 2015).
Gut microbiota also contribute to the production of micronutrients and their absorption. They synthesize most of the body’s vitamin K and B vitamins from precursors we intake from our diets, and aid in the absorption of calcium and magnesium, potentially enhancing calcium uptake by up to 50%.
A healthy microbiota also play a crucial role in the development and regulation of the immune systems. They help “train” immune cells to distinguish between harmful and harmless agents, reducing the risk of autoimmune reactions.
The diversity and type of the microbiome can metabolize phytonutrients to their active form. For example, isoflavones are usually consumed as glycosides (bound to sugars) and broken down to aglycones by probiotics. Daidzein (soy isoflavone) is converted to phytoestrogen “equol” by lactobacilli and bifidobacteria. Phytonutrients are found naturally in plant foods and give fruits, vegetables, herbs, and whole grains their vibrant colours, flavours, and aromas, and they help protect our own cells from damage and support key biological processes.
A healthy gut flora also supports digestion, reduces bloating, and plays a role in immunity and even mood regulation.
2. Promotes Heart Health
Several studies have shown that soluble fibre helps lower LDL (bad) cholesterol levels by binding to bile acids in the intestines and carrying them out of the body, with one study showing that for each gram of soluble fibre (2-10 g/day), there were small but significant decreases in total cholesterol and LDL cholesterol, while another showing water-soluble fibre can reduce total & LDL cholesterol by about 5-10 %. The reduction of LDL cholesterol is linked with the reduced risk of heart disease and stroke over time.
The body’s liver uses cholesterol to make bile acids, and normally, bile acids are reabsorbed back into the bloodstream after digestion. However, when soluble fibre is present, it traps these bile acids and carries them out of the body through the stool, requiring the liver to then use more cholesterol from the bloodstream to make new bile acids, which results in lower LDL cholesterol levels in the blood (Brown et al., American Journal of Clinical Nutrition, 1999).
3. Supports Weight Management
Weight management is about more than just calories, and managing body weight is also about how foods affect hunger, fullness, hormones, and energy balance. Fibre plays a unique role in this process as it’s one of the few nutrients that directly impacts appetite regulation, blood sugar stability, and above mentioned gut health.
Fibre slows down how quickly food leaves your stomach, which means you feel full and satisfied for longer after eating. Soluble fibre absorbs water and forms a gel-like texture in your digestive tract, thereby increasing the volume and viscosity of your meal, stretching the stomach and activating satiety signals to the brain through hormones (like GLP-1, PYY, and leptin). Studies show that higher-fibre meals can reduce subsequent calorie intake by up to 10–15%, without conscious restriction (Wanders et al., Obesity Reviews, 2011). For example, a bowl of porridge with oats, chia seeds, and berries keeps you full far longer than white toast and jam, even if both meals have similar calories.
High-fibre foods slow down physical digestion by taking longer to chew and digest. This steadies blood sugar levels, preventing sharp spikes and crashes that trigger hunger and cravings, and reduces the inconsistent secretion of insulin, (the hormone that promotes fat storage when chronically elevated).
When you eat refined carbs (white bread, sweets, sugary cereals), blood sugar rises quickly and falls rapidly, leading to hunger soon after. By contrast, fibre-rich foods (like wholegrains, beans, fruits, and vegetables) provide a steady release of glucose, helping to maintain energy and appetite control throughout the day (Nutrients, 2019).
The gut microbiota ferment fibre to produce SCFA described above which also regulate hunger hormones, improve insulin sensitivity, enhance fat metabolism, and reduce low-grade inflammation associated with obesity (The American Journal of Clinical Nutrition (2020).
4. Balances Blood Sugar Levels
When it comes to managing energy, appetite, and long-term metabolic health, blood sugar balance is crucial. Sharp spikes and crashes in blood glucose not only affect how you feel day to day, but they also increase the risk of type 2 diabetes, insulin resistance, and weight gain.
Unlike refined carbohydrates (found in white breads, white rice, white pasta etc) that are broken down quickly into glucose, fibre slows down the entire digestive process, and helps lower the glycaemic index of foods (a measure of how quickly glucose from food is absorbed into the bloodstream). When soluble fibre mixes with water in the gut, it forms a thick gel-like substance that delays the emptying of the stomach (you feel full longer), it slows the breakdown of starch into glucose, and reduces the rate of glucose absorption in the small intestine, meaning that instead of a sharp rise in blood sugar after a meal, you get a gentler, more sustained increase, and less insulin is required to manage it (Jenkins et al., American Journal of Clinical Nutrition, 2000).
Insulin is the hormone responsible for moving glucose from the bloodstream into cells. Together with the reduced insulin spikes preventing “insulin fatigue” and improved insulin pathways in the liver and muscles from the production of SCFA as described above, and lower, and lower inflammation and improved lipid metabolism supported from high-fibre diets, your body the body can maintain a healthy insulin sensitivity when high fibre food is eaten regularly, meaning it can manage blood sugar more efficiently (Reynolds et al., The Lancet Public Health, 2019).
5. Prevents Constipation
One of the most well-known, but often oversimplified benefits of dietary fibre is its role in the prevention of constipation, one of the most common digestive complaints affecting people of all ages, leading to discomfort, bloating, and can even affect mood and energy levels.
Insoluble fibre adds “bulk” to your stool and acts like a sponge, absorbing water and increasing stool volume. It also helps speed up the movement of waste through the intestines and reduces the transit time in the gut, preventing stool from hardening. The gel-like texture produced from soluble fibre softens the stool further, making it easier to pass out and maintains comfortable, regular bowel movements without straining.
Boosting Your Fibre Intake
Start your day fibre-first! Choose high-fibre cereals and breads, topped with fruits
Switch to Wholegrains
Load Up on Vegetables (which contain both soluble and insoluble fibre)
Keep the Skin On - skins of fruits and vegetables are packed with insoluble fibre
Eat Fruit Every Day (Not Just Juice)
Add Legumes (Beans, Lentils, Peas) to meals
Snack on Nuts and Seeds
Upgrade Your Baking by add fibre to baked goods e.g., Adding bran, oats, or ground flaxseed to muffins, pancakes, or breads.
Blend, Don’t Juice! When you juice fruit or vegetables, most of the fibre is lost. Blending keeps the fibre intact.
Add “Hidden” Fibre Boosters to Everyday Foods. Try adding Psyllium husk, Flaxseed, oat bran, chia seeds to a variety of potential dishes.
Read Labels & Choose Higher-Fibre Packaged Foods. Look for ≥3g fibre per 100g = “source of fibre” or ≥6g fibre per 100g = “high in fibre”
Finally…If you’re increasing fibre in your diet, do it gradually and drink plenty of water. A sudden increase can lead to bloating or discomfort as your body adjusts.
