Why Your Body Needs Fibre — And Most People Don't Get Enough

What Fibre Actually Does Inside Your Body

Fibre's reputation as a digestion aid is well earned, but its effects extend well beyond keeping things moving. Here's what's happening once fibre enters your system.

Digestive regularity: Insoluble fibre adds bulk to stool and speeds its passage through the intestines, reducing the likelihood of constipation. Soluble fibre absorbs water and forms a gel, softening stool and slowing digestion in a way that helps regulate how quickly nutrients — including glucose — enter the bloodstream.

Blood sugar management: That gel-forming property of soluble fibre slows the absorption of sugar from food, blunting sharp spikes in blood glucose after meals. Over time, a consistently high-fibre diet is associated with better blood sugar control, which is relevant for long-term metabolic health.

Heart health: Soluble fibre — particularly a type called beta-glucan found in oats and barley — can bind to cholesterol-containing bile acids in the digestive tract and help remove them from the body. Research links higher fibre intakes to lower LDL ("bad") cholesterol levels and reduced risk of cardiovascular disease.

Gut microbiome support: Certain types of fibre act as prebiotics — essentially food for the beneficial bacteria living in your large intestine. A well-fed microbiome produces short-chain fatty acids that support the gut lining, regulate inflammation, and may even influence mood through the gut-brain connection.

“Dietary fibre is one of the most important yet consistently underconsumed nutrients in the modern diet. Its benefits span from gut health to cardiovascular protection — and most of those benefits are accessible simply by eating more whole plant foods.”

— Joanne Slavin, Professor of Food Science and Nutrition, University of Minnesota

Why the Fibre Gap Is So Wide

The gap between recommended and actual fibre intake is striking — and it's largely a product of how modern diets are structured.

Ultra-processed foods — which make up a large share of calories in the average American diet — are typically low in fibre or contain none at all. Refined grains, a staple in many households, have had much of their fibre-rich bran and germ removed during processing. Meanwhile, whole plant foods, which are the primary fibre sources, are simply not present in sufficient quantities for most people.

It's worth noting that this isn't purely a matter of individual choice. Access to fresh produce and whole grains, food preparation time, cost, and cultural food patterns all shape what ends up on the plate. Understanding the broader context helps frame fibre intake as a structural nutrition issue, not just a personal failing.

Practical Ways to Add More Fibre

Increasing fibre doesn't require an overhaul of your entire diet. Small, consistent substitutions tend to be more sustainable than dramatic changes — and they add up meaningfully over time.

• Swap refined grains for whole grains: Choose whole wheat bread, brown rice, or oats over their refined counterparts. The difference in fibre content can be significant per serving.
• Add legumes regularly: Beans, lentils, and chickpeas are among the most fibre-dense foods available and are also affordable and shelf-stable. Stir them into soups, salads, or grain bowls.
• Keep the skin on fruits and vegetables: Much of the fibre in apples, pears, potatoes, and similar foods sits in or just beneath the skin. Leaving it intact preserves that benefit.
• Snack on nuts and seeds: A small handful of almonds, chia seeds sprinkled on yogurt, or flaxseed added to a smoothie are easy, low-effort boosts.
• Go gradually: Increasing fibre too quickly can cause gas and bloating. Spacing out changes over two to four weeks gives your digestive system time to adapt. Drinking enough water is equally important, as fibre needs fluid to do its job.

For a broader look at the nutrients your body depends on, see our guide to vitamins and minerals — fibre works best alongside a diet rich in micronutrients.

This article is for general informational purposes only and is not a substitute for professional medical or dietary advice. If you have a health condition or specific nutritional concerns, please consult a qualified healthcare provider.