Benefiber Prebiotic Fiber Supplement Market Report: Sales Volume, Market Share, Leading Brands & Market Trends

Metamucil is the best-performing benefiber prebiotic fiber supplement brand in July 2026, moving 160,000 units across 3 ASINs for 34.0% of Top 10 volume. Physician's CHOICE follows with 90,000 units (19.1%), ahead of Amazon Basics on 60,000 units (12.8%).

With 7 brands splitting the Top 10 and 66.0% of volume sitting with three of them, this is a concentrated shelf — the leaders hold multiple listings or one very high-velocity ASIN, so a new entrant competes against established review moats rather than an open field. Average selling prices among the leaders run from $9.74 to $28.35, which frames the price band a competing listing has to justify.

Based on July 2026 data, this shortlist surfaces the two kinds of ASIN worth keeping an eye on — the ones that just broke into the Top 10, and the ones growing fastest month over month. Specifically, one ASIN forced its way in: B001TH7K0G booked 40K units at $25.13, with ▲ 100.0% MoM change. On the growth side, B004JO3JTM leads positive momentum with ▲ 122.2% MoM growth on 20K units, with B0G1D2XDDJ close behind at ▲ 66.7% MoM on 5K units.

The two signals carry different weight. A fresh entrant means share has already changed hands — an incumbent gave up its place to make room, so any competitive set drawn up a month ago is now out of date. A steep growth rate works as the earlier warning: it marks demand that is still compounding, usually a month or two before the ranking catches up to it.