If you've ever stood in the supplement aisle wondering whether you need psyllium or inulin, here's the short answer: the interesting part isn't choosing between them — it's what happens when you put them together.
They're both fibre, but they do genuinely different jobs. Understanding that is the whole reason Mr. Regular is built the way it is.
Two fibres, two jobs
Psyllium is a viscous, gel-forming fibre. When it meets water, it turns into a soft gel that adds bulk, holds moisture, and helps things move through comfortably and predictably. It's one of the most well-studied fibres for supporting regularity — and it's gentle, because your gut bacteria don't ferment much of it.
Inulin is a prebiotic, fermentable fibre. It doesn't form a gel; instead, it travels to your large intestine where your beneficial gut bacteria feed on it. As they ferment it, they produce short-chain fatty acids — compounds linked to a healthier gut lining and a more balanced microbiome. In other words, inulin is food for the good bugs.
So one fibre helps with the mechanics of regularity, and the other helps feed your microbiome. Neither one fully does the other's job — which is exactly why pairing them makes sense.
The part most people don't know
Fermentable fibres like inulin have one well-known trade-off: because bacteria ferment them, they can produce gas. For some people, that means bloating — which is why prebiotics sometimes get a bad reputation.
Here's the interesting bit. In a randomized crossover study published in Alimentary Pharmacology & Therapeutics (2022), researchers gave participants inulin on its own, psyllium on its own, or the two combined. Inulin alone produced a large spike in colonic gas. But when psyllium was taken alongside inulin, that gas response dropped dramatically — the peak hydrogen response fell from around 7,230 to roughly 1,035 ppm·hour, along with less bloating.
The takeaway: psyllium seems to help smooth out inulin's main downside. Pairing a viscous fibre with a fermentable one appears to let you enjoy the prebiotic benefits of inulin more comfortably than taking inulin on its own.
Why fibre diversity matters
There's a bigger principle underneath this. Your gut isn't home to one type of bacteria — it's a whole community, and different bacteria thrive on different fibres. A growing body of microbiome research points in the same direction: a variety of fibre types tends to support a more diverse, resilient gut community than any single fibre on its own.
Most of us don't eat nearly enough fibre to begin with, and what we do eat tends to be low in variety. A supplement that combines complementary fibre types is a simple way to widen that range without overhauling your diet.
How Mr. Regular puts this to work
This is the thinking baked into every scoop.
Original pairs organic psyllium husk with Orafti® inulin — the everyday combination of regularity plus gentle prebiotic support, in a smooth vanilla shake with no grit.
+Prebiotic adds a third fibre: Solnul® resistant starch, a clinically studied RS2 that gives your microbiome even more to work with — for people who want to lean further into gut support.
Both are designed around one idea: fibre only works if you actually take it. Smooth taste, no grit, no added sugar, and one simple daily habit — so the science can do its job.
The honest bottom line
There's no magic in any single fibre. The real advantage is combining fibres that do different things: one to support regularity and comfort, one to feed your microbiome — together, more comfortably than either does alone. That's not a marketing trick. It's just how fibre works.
One shake. One simple daily habit. Shop Mr. Regular →
References
- Gunn D, Abbas Z, Harris HC, et al. Psyllium reduces inulin-induced colonic gas production in IBS: MRI and in vitro fermentation studies. 2022. Read the study.
- The role of different dietary fibers in modulating the human gut microbiota (review). MDPI. Read the review.
- Bush JR, Baisley J, Harding SV, Alfa MJ. Consumption of Solnul™ resistant potato starch produces a prebiotic effect in a randomized, placebo-controlled clinical trial. Nutrients. 2023;15(7):1582. Read the study.
This article is for general educational purposes and isn't medical advice. If you have a digestive condition such as IBS, introduce new fibre gradually, drink plenty of water, and check with your healthcare provider.