Fibre, prebiotics and your gut: the basics
"Fibre" is one of those words we all nod along to and few of us could actually define. Most of us know we should get more of it. Fewer of us could say what it is, why "soluble" and "insoluble" matter, or what your gut bacteria are doing with the stuff once it arrives. So here's the plain version — no hype, no promises, just the science, simply.
Belo makes food, not medicine, so nothing here treats, prevents or manages any condition. This is a short tour of how dietary fibre works in the body, written for anyone who wants to understand what's on the back of the pack before they buy it.
This is general information, not medical advice. It is not a substitute for guidance from your own doctor or an accredited practising dietitian.
What dietary fibre actually is
Fibre is the part of plant foods your small intestine can't break down and absorb. Where sugars, starches, fats and proteins get digested and taken up higher in the gut, fibre largely passes through intact — which turns out to be the whole point. Because it survives the journey, it can do useful physical and microbial work along the way (Gill et al., 2021).
That "can't digest it" definition covers a big, varied family: the cellulose in wholegrains and vegetables, the beta-glucans in oats and barley, the pectin in fruit, resistant starches, and a range of extracted and manufactured fibres used in foods and supplements. They don't all behave the same way, which is exactly why one word is doing too much work when people just say "fibre" (Slavin, 2013).
Soluble vs insoluble — the useful split
The oldest and most useful way to sort fibres is by whether they dissolve in water.
Insoluble fibre doesn't dissolve. Think wheat bran, the skins of fruit and veg, the fibrous structure of wholegrains. Its main job is mechanical — adding bulk to stool and helping move things along the gut. It's the "roughage" your grandmother meant.
Soluble fibre dissolves into a gel-like consistency in water. This is the group that slows the passage of food through the upper gut, and — importantly for this article — the group that your gut bacteria are most interested in (Slavin, 2013). Oats, legumes, psyllium and a lot of extracted supplement fibres sit here.
It's not a perfect binary. Real foods carry a mix, and modern reviews increasingly describe fibres by their measurable properties — solubility, viscosity (how gel-forming they are) and fermentability (how readily bacteria eat them) — because those properties, not the label alone, predict what a fibre does (Gill et al., 2021). But "soluble vs insoluble" is still the right first mental model, and it's where the gut-health story gets interesting.
Prebiotics: feeding the bugs
Your large intestine is home to trillions of bacteria. When fermentable fibre reaches them, they get to work on it — a process called fermentation. This is where the word prebiotic comes in.
An international expert panel defines a prebiotic as "a substrate that is selectively utilized by host microorganisms conferring a health benefit" (Gibson et al., 2017). In plainer terms: a prebiotic is food for your gut microbes, not for you directly. Not every fibre is a prebiotic, and not every prebiotic is a classic fibre — but many well-studied fermentable fibres fall into this overlap. Feeding your resident bacteria in this way can shift the makeup and activity of the gut community (So et al., 2018).
The honest caveat, straight from the research: the size and direction of those microbial changes vary a lot between different fibres and between different people. Fibre is not one lever with one predictable result — it's a whole toolkit, and individual responses differ (So et al., 2018).
Short-chain fatty acids: the fermentation payoff
Here's the part that makes fermentation more than a curiosity. When gut bacteria ferment fibre, one of the main things they produce is a group of molecules called short-chain fatty acids (SCFAs) — chiefly acetate, propionate and butyrate (Gill et al., 2021).
These SCFAs are a key reason fibre and the microbiome get discussed together so often. Butyrate, for instance, is a preferred fuel source for the cells lining the colon, and SCFAs more broadly are an active area of research into how the gut communicates with the rest of the body (Slavin, 2013; Gill et al., 2021). We'll stop the science there deliberately: this is a live research field, and it would be dishonest to turn "researchers are studying this" into "this product does that". What's fair to say is simpler — fermentation of fibre produces SCFAs, and that's a big part of why fibre matters to the gut.
How much fibre — the Australian numbers
You don't have to guess at a target. Australia's National Health and Medical Research Council sets an Adequate Intake for dietary fibre of 25 g a day for adult women and 30 g a day for adult men, with a higher Suggested Dietary Target for those aiming to reduce chronic-disease risk (NHMRC Nutrient Reference Values). For context, national survey data suggests many Australian adults fall short of even the Adequate Intake — so "more plants, more variety" is sound, unglamorous advice for most people.
Whole foods first, always: a diet built on wholegrains, legumes, vegetables, fruit, nuts and seeds delivers fibre in its natural context, and that's the foundation nothing supplements. A fibre powder is a top-up, not a replacement for that plate.
Where the Belo 6-in-1 fits — and where it doesn't
We built our around one idea that runs through everything we do: show every gram. A 12 g serve delivers 11 g of soluble fibre from six named sources — soluble corn fibre, gum arabic (acacia), PHGG (partially hydrolysed guar gum), polydextrose, sodium alginate (from kelp) and citrus pectin — plus a trace of silicon dioxide to stop it clumping. We name every source rather than hiding behind a "proprietary blend", and you can see the full breakdown on the . It's unflavoured and dissolves into any drink, with no added sugar, sweeteners or flavours.
We describe those grams factually rather than dressing them up as a formal nutrition claim; the regulated wording that can appear on a label is set with our label consultant, not in a blog post. The reason we favour a disclosed multi-fibre blend is the same reason we publish our sea moss lab reports at our : you should be able to see what you're getting, source by source, rather than trust an undisclosed "proprietary blend".
And in the spirit of honesty, here's who the 6-in-1 is not for:
- If you just want cheap bulk fibre, a single-ingredient psyllium or bran is a perfectly good, cheaper choice.
- If a clinician has put you on a specific single fibre for a specific reason, follow their advice — a six-fibre blend isn't what they asked for.
- If your fibre is coming along nicely from food, you may not need a powder at all. Diet first.
Different fibres suit different bellies, and the right amount is the one you build up to gently with plenty of water. If you have a diagnosed gut condition, are pregnant, or take medication, talk to your doctor or an accredited practising dietitian before adding any new fibre supplement — that's where individual advice belongs, and a blog can't give it. Good for your belly starts with good information.
References
- Gill SK, Rossi M, Bajka B, Whelan K. Dietary fibre in gastrointestinal health and disease. Nature Reviews Gastroenterology & Hepatology. 2021;18(2):101–116. doi:10.1038/s41575-020-00375-4
- Slavin J. Fiber and prebiotics: mechanisms and health benefits. Nutrients. 2013;5(4):1417–1435. doi:10.3390/nu5041417
- Gibson GR, Hutkins R, Sanders ME, et al. Expert consensus document: The International Scientific Association for Probiotics and Prebiotics (ISAPP) consensus statement on the definition and scope of prebiotics. Nature Reviews Gastroenterology & Hepatology. 2017;14(8):491–502. doi:10.1038/nrgastro.2017.75
- So D, Whelan K, Rossi M, et al. Dietary fiber intervention on gut microbiota composition in healthy adults: a systematic review and meta-analysis. The American Journal of Clinical Nutrition. 2018;107(6):965–983.
- National Health and Medical Research Council. Nutrient Reference Values for Australia and New Zealand — Dietary Fibre.
- Monash University. Low FODMAP Diet program (IBS research and app).