Casein Protein Powder Market Report: Sales Volume, Market Share, Leading Brands & Market Trends

Optimum Nutrition is the best-performing casein protein powder brand in July 2026, moving 50,000 units across 2 ASINs for 26.5% of Top 10 volume. Orgain follows with 40,000 units (21.2%), ahead of Premier Protein on 30,000 units (15.9%).

With 8 brands splitting the Top 10 and 63.5% 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 $27.57 to $52.00, 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, 2 ASINs forced its way in: B0FST375QH booked 10K units at $22.88, with ▲ 25.0% MoM change. On the growth side, B06ZZ3PJQD leads positive momentum with ▲ 200.0% MoM growth on 30K 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already changed hands — an incumbent gave up its place to make room, so any competitive set drawn up a month ago is now out of date.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.