Cluster Dextrin: The “Next-Gen” Carb That’s Changing How Endurance Athletes Fuel

If you read our recent blog about the Tour de Palm Springs CGM experiment (https://wix.to/74aPwjU), you saw that two of the riders used Skratch's Super High-Carb on several segments. That product is built around cluster dextrin (also called Highly Branched Cyclic Dextrin or HBCD), where riders should notice flatter, more stable glucose curves on those days, compared to simple sugar hydration mixes.

After getting questions about it, I decided to dig deeper. Here’s a clear, balanced look at what cluster dextrin actually is, why it’s gaining popularity, who uses it, the real benefits, and the potential downsides.

What Is Cluster Dextrin?

Cluster dextrin is a highly branched cyclic dextrin - a complex carbohydrate made from amylopectin (the branched part of starch). It’s produced through a patented enzymatic process that creates a unique molecular structure: a central ring with many short glucose chains branching off.

This structure gives it three key properties that regular maltodextrin and simple sugars don’t have:

• Very low osmolarity (doesn’t pull much water into the gut)

• Extremely fast gastric emptying (leaves the stomach quickly)

• Slower, more sustained absorption in the small intestine

In plain English: it delivers a steady stream of carbs without the stomach sloshing, big glucose spikes, or crashes that many athletes experience with traditional high-carb mixes.

Who Makes Products with Cluster Dextrin?

• Skratch Labs: Their Super High-Carb drink mix is one of the most popular in the U.S.

• Maurten: Uses a similar (but proprietary) form in their high-carb gels and drinks (though they market it differently).

• Neversecond: C90 and C60 drinks use cluster dextrin.

• Science in Sport (SIS): Beta Fuel uses a blend that includes cluster dextrin.

• Precision Fuel & Hydration: PF 90 and 120 gels/drinks.

• Torq: Several of their high-carb products.

• Japanese brands:

  Many pro cycling teams in Asia use pure Cluster Dextrin powders from Ezaki Glico or similar suppliers.

Claimed Benefits (and What the Research Says)

1. Less GI Distress - Multiple studies show cluster dextrin causes significantly less stomach discomfort than maltodextrin at high intakes (60–120 g/hour). This is the #1 reason endurance athletes switch to it.

2. Steady Blood Glucose - Because of slower digestion, it produces flatter glucose curves with fewer spikes and crashes — not exactly what we saw in the Palm Springs data with the riders who used Skratch's Super High-Carb.

3. Higher Carb Oxidation Rates - Some research shows athletes can oxidize (use) more carbs per hour with cluster dextrin than with maltodextrin, which is useful for very long or very intense efforts.

4. Faster Gastric Emptying - It leaves the stomach quicker, so you feel less full and can keep drinking/eating comfortably.

Potential Downsides

• Cost - It’s significantly more expensive than maltodextrin or simple sugar mixes.

• Not Magic - Some athletes still get GI issues at very high doses (>90–100 g/h). Individual tolerance varies.

• Limited Long-Term Data - Most studies are short (2–4 hours). We don’t have decades of data like we do with maltodextrin.

• Taste & Mixability - Some people find the flavor milder or the powder harder to mix than traditional drinks.

How It Fits Into the Palm Springs Experiment

In our small group test, the riders who drank using cluster dextrin (Skratch's Super High-Carb) did not show noticeably flatter glucose curves compared to the riders consuming more simple sugar mixes. Now the study had no controls nor did it limit the riders on what they could or could not consume. Other products were consumed along with Skratch's Super High Carb mix. But maybe the cluster dextrin still helped prevent big spikes while still providing steady fuel for these 2 riders. We will continue to look closely at cluster dextrin with a current study that is being run. It's much more controlled and looks at a couple different products and their effects on glucose levels during and after exercise. We hope to publish that in the near future.

Practical Takeaway for Athletes

Cluster dextrin is currently one of the best tools we have for high-volume carb fueling with reduced GI risk. If you’re training or racing for 3+ hours and want to push 60–90+ g of carbs per hour, it’s worth taking a look at.

At Project Blue, we now recommend athletes experiment with it during long training rides and use a continuous glucose monitor to see how their personal glucose response compares to cluster dextrin or simple sugar mixes. Our goal is to keep athletes away from the risk of diabetes and any metabolic disease that impact your health or performance!

Let me know your thoughts in the comments! How do you like to fuel? Do you think it is effective or do you wish you had more information around your personal metabolism?