Stool form and regularity
GoBiotix Prebiotic Fiber Boost
An unflavored once-a-day powder of 5 g of short-chain fructooligosaccharide prebiotic fiber that mixes into any drink.
- Format
- Powder, once a day
- Type
- Fiber and prebiotic
- Cost
- $0.83 a day
- Customer rating
- 4.4 out of 5 from 12,741 ratings from Amazon
What customers consistently report
- Dissolving with no taste or grit in coffee, water or a smoothie
- More regular bowel movements and less bloating for most reviewers
- Being easier on the stomach than other fiber supplements
Those are the themes that recur across the reviews. Moderate review confidence — Amazon shows 4.4 from 12,741 ratings and the brand’s own page shows 4.7 from 4,576 reviews (some from related products), while Trustpilot covers the whole store (681 reviews) and its score does not match its star split.
Why it might work
Short-chain fructooligosaccharides (FOS) are chains of three to five sugar units that the small intestine does not digest, so they reach the colon intact. Gut bacteria, mainly bifidobacteria, ferment them into short-chain fatty acids and gas. That fermentation is how the fiber is meant to feed beneficial bacteria and soften stool, and it is also why gas and bloating are the common side effects. Fructooligosaccharides are fructans, a fermentable carbohydrate group that can worsen symptoms in some people with irritable bowel syndrome, although the jar image calls the formula low-FODMAP. The label does not let you check that claim, the testing laboratory, or the source of the 95% purity figure.
What the research supports
The evidence is for the ingredient class, not this product. In the one dose-response trial of 40 healthy adults, 5 g a day of short-chain fructooligosaccharide for a week raised fecal bifidobacteria, but bloating was significantly more intense than on placebo at 2.5 and 5 g a day. A meta-analysis of 17 trials (713 people) found more bowel movements and softer stools with fructooligosaccharides, with mild bloating as a recorded side effect. The two studies of the branded ingredient, FOSSENCE P95, measured blood sugar and test-tube fermentation, not symptoms.
What the label discloses
One active at a disclosed 5 g per scoop, plus silicon dioxide as an anti-caking agent, so there is no proprietary blend to decode. The label image shows a third-party-tested mark but no laboratory is named in the page text, and there is no allergen or facility statement on the label. The same jar is priced $30.99 on one brand page and $49.99 on an ad landing page.
Who this tends to suit
We match this product to people reporting bloating, gas, irregular bowel habits and constipation. It fits someone whose priority is day-to-day comfort, regularity or a steady daily routine. Whether it is the best fit for you depends on the rest of your answers — what you have already tried, what format you will take, and anything that has to be ruled out.
Where it may not fit
The label supports vegan, gluten-free, dairy-free, no added sweeteners and minimal ingredient list. A powder only works if you will take it once a day, every day.
Side effects and what to be aware of
About 10% of Amazon’s digestive-effect mentions are negative, and the brand’s own FAQ warns of mild gas for the first three to five days and suggests starting with half a scoop. On Trustpilot, which covers the whole store, a few reviews describe trouble cancelling a subscription or receiving expired product. The label carries no pregnancy, medication or medical-condition warning.
Common questions
Does GoBiotix Prebiotic Fiber Boost work?
It is 5 g of short-chain fructooligosaccharide (FOS) per scoop. In trials, 5 g a day of FOS raised fecal bifidobacteria in healthy adults and a meta-analysis of 17 trials found more bowel movements, but the one dose-response trial found bloating was higher than placebo at 5 g. No trial of Fiber Boost itself exists; its 4.4 stars on Amazon from 12,741 ratings reflect customer opinion, not a trial.
Is GoBiotix Fiber Boost safe, and what are the side effects?
The label shows one ingredient, FOS, with silicon dioxide as an anti-caking agent, and no warnings. The brand says mild gas in the first three to five days is normal and suggests half a scoop for the first week, and trials list bloating as the usual side effect. Fructans such as FOS made symptoms worse in some people with irritable bowel syndrome in trials.
How much does GoBiotix Fiber Boost cost?
One 35-serving tub is $30.99 on the standard brand page ($0.89 a day), $24.79 on its 20% Subscribe & Save plan, and $28.97 on Amazon ($0.83 a day). An ad landing page for the same labeled jar shows $49.99, or $37.49 on subscription, so check which page you are on before ordering.
GoBiotix Fiber Boost vs a psyllium fiber: what is different?
Fiber Boost is 5 g a day of fructooligosaccharide, a fermentable prebiotic, and its jar says no psyllium, no bloat, which is a brand claim. Psyllium is a gel-forming fiber that was one of the two fibers with significant effects in a 2022 constipation meta-analysis. No head-to-head trial of the two was found.
How do I cancel a GoBiotix subscription or get a refund?
GoBiotix has 4.3 stars on Trustpilot from 681 reviews with 4% one-star, and a few reviews from 2023 and 2024 describe trouble cancelling a subscription; the most recent one-star is about expired product. Its written policy accepts returns of unopened, unused product within 30 days, while an ad landing page promises a 60-day guarantee; cancel a subscription through the links in the order email or by emailing the brand.
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Related reading
Background on how this type of product works, read from the trial evidence.