Fibre deep dive

What it really does for your gut, inflammation and even microplastics

Fibre has had an interesting journey through nutrition science. For years it sat quietly in the background, filed under "good for digestion" and not much else. Now it is everywhere, linked to gut health, inflammation and cholesterol, with people calling it "the new protein" (it's not; they are equally important).

But more recently, the headline-grabbing question is whether fibre can help our bodies deal with microplastics – and I personally feel that this attention is deserved.

Microplastics have been found in human blood samples. Although there is understandable concern about the impact this could have on human health, the details are not yet known.

What Is Fibre, Really?

Fibre is the part of plant foods the body cannot fully digest. It is generally grouped into two types: soluble and insoluble. Most plant foods contain a mix of both.

Soluble Fibre

Dissolves in water and forms a gel. Slows digestion, helps regulate blood glucose and may support healthy LDL cholesterol. Found in oats, barley, beans, lentils, psyllium husk, apples, pears and citrus.

Insoluble Fibre

Adds bulk to stool and helps food move through the gut. Found in wheat bran, whole grains, nuts, seeds, and fruit/vegetable skins.

How Much Fibre Do UK Adults Actually Need?

Most UK adults consume around 18g a day – just 60% of the recommended 30g – and only 4% of adults actually hit that target. The average intake gap matters. Fibre is linked to lower risk of cardiovascular disease, type 2 diabetes and bowel cancer.

Fibre and the Gut Microbiome

Fibre that resists digestion reaches the colon largely intact, where gut bacteria ferment it – producing short-chain fatty acids including butyrate, propionate and acetate. These compounds help maintain the gut lining and support a healthy immune response. Research links them to regulating appetite and blood sugar.

A study of over 300 men found higher fibre intake was associated with lower C-reactive protein and a gut microbiome enriched in butyrate-producing bacteria – though effects varied by individual gut composition.

Fibre, Blood Sugar and Cholesterol

Soluble fibre slows carbohydrate absorption and binds to bile acids, prompting the body to draw more cholesterol from the blood. Oats and barley, rich in beta-glucan, are among the better studied foods for this.

The Emerging Research Angle: Fibre and Microplastics

Some emerging research is exploring whether dietary fibre – particularly chitosan – may help bind to microplastic particles in the gut and support their elimination. One 2025 study in rats found animals fed chitosan excreted significantly more microplastics than a control group.

Chitosan comes from shellfish skeletons – not appropriate for anyone with a shellfish allergy.

The evidence so far comes almost entirely from animal and lab studies. A more accurate summary is that this is a promising, early-stage research area worth watching.

Building a Fibre-Friendly Routine

• Swap refined grains for wholegrain versions
• Add beans, lentils or chickpeas to meals a few times a week
• Keep the skin on fruit and vegetables where you can
• Add a tablespoon of chia, flax or pumpkin seeds to porridge or yoghurt
• Aim for at least five portions of varied fruit and vegetables a day
• Increase water intake alongside any increase in fibre

Where Gut Health Fits Into Your Wider Wellness Routine

Tonic's Immunity + Vitality is designed to complement this kind of routine, with 11 well-dosed vitamins, minerals and plants including those that support your gut and immune system. Find out more about adaptogens and how they earn their place in the formula.

The Takeaway

• Most people – adults and children – would benefit from more fibre
• Increase intake gradually and stay well hydrated
• Choose from a variety of sources
• The microplastics research is interesting but early – one to watch, not overstate

If you want family-friendly ways to build fibre habits early, read: Five Sneaky Ways to Add More Fibre to Your Kids' Diet.

This article is for informational purposes only and does not constitute medical advice. If you have concerns about your digestive health or nutrition, please consult a qualified healthcare professional.

About the Author

Natalie Louise Burrows is a registered nutritional therapist (BANT, CNHC) and clinic director at Integral Wellness – a nutrition and health clinic specialising in cardio-metabolic health. Along with her clinic team of nutritionists, they help men and women regain their energy, control their cravings and avoid and reverse type 2 diabetes. They also address health conditions such as high blood pressure, high cholesterol, insulin resistance, fatty liver and heart disease, and weight challenges.