C4 Launches Sparkling Protein, Entering a Fast-Growing Clear RTD Beverage Category

Nutrabolt has introduced C4 Sparkling Protein, a caffeine-free, ready-to-drink beverage that extends its C4 brand, long associated with energy drinks and pre-workout supplements, into the sparkling protein beverage category.¹

The launch reflects a broader shift already underway in the ready-to-drink protein segment, where clear and carbonated formats have outpaced more traditional dairy-based shakes in recent sales growth.

"More people than ever are prioritizing protein as part of their wellness routines, but they don't want to sacrifice taste to get it," said Emily Hoyle, senior vice president of marketing at Nutrabolt. "Sparkling and clear protein drinks have a reputation for tasting flat or leaving behind a chalky mouthfeel, and we knew that wasn't good enough for C4. We took our best-in-class flavor expertise and applied it to this new format, so consumers get a protein beverage that's as enjoyable to drink as it is functional."

How Big Is the Ready-to-Drink Protein Beverage Category Right Now?

The US ready-to-drink protein supplement market grew 7.5% year over year to nearly $6.5 billion in the 52-week period ending in April 2026, according to SPINS retail sales data.² Within that broader category, clear protein RTD shakes specifically drove the highest sales growth of any format in 2025, posting a 34% increase, followed by ultrafiltered dairy-based drinks at 25% growth and protein waters, shots, and sodas at 12% growth.³

That data suggests C4 Sparkling Protein is entering the segment at a point of particularly strong momentum, though it also means the format is drawing a growing number of new entrants competing for the same shelf space.

Why Have Clear and Sparkling Protein Formats Been Difficult to Formulate Well?

Achieving a clear or lightly carbonated appearance in a high-protein beverage requires different processing than a traditional dairy-based shake. Standard whey protein concentrate retains fat and other components that scatter light and produce an opaque, cloudy appearance, so clear formulations typically rely on a more heavily purified, and often hydrolyzed, whey protein isolate to remain in solution without clouding the liquid.

Achieving stability under carbonation adds a further formulation challenge, since dissolved protein and carbonation can interact in ways that affect mouthfeel, foaming, and shelf stability if not carefully balanced. Hoyle's comment about sparkling protein drinks having "a reputation for tasting flat or leaving behind a chalky mouthfeel" reflects a formulation challenge that has been widely discussed across the category, rather than one specific to this launch.

What Should Manufacturers Take Away From This Launch?

C4 Sparkling Protein illustrates a now-common strategy among established supplement and beverage brands: extending an existing brand identity into an adjacent, faster-growing format rather than launching an entirely new brand. For manufacturers, the more instructive detail may be less about the marketing positioning and more about the underlying formulation demands, delivering 20 g of protein in a zero-sugar, carbonated format at a stated price point requires ingredient sourcing and processing decisions that go beyond simply adding carbonation to an existing protein shake recipe.

References

1. C4 expands beyond energy drinks with the launch of Sparkling Protein. PR Newwire. Published July 30, 2026. https://www.prnewswire.com/news-releases/c4-expands-beyond-energy-drinks-with-the-launch-of-sparkling-protein-302838448.html

2. Golden S. Clear mission: the innovations behind protein's refreshing surge. BevNET. June 19, 2026. Accessed August 7, 2026. https://www.bevnet.com/magazine/issue/2026/clear-mission-the-innovations-behind-proteins-refreshing-surge

3. Lyubomirova T. How protein is shaping active nutrition in 2026. DairyReporter. March 15, 2026. Accessed August 7, 2026. https://www.dairyreporter.com/Article/2026/03/15/how-protein-is-shaping-active-nutrition-in-2026/