Best Carbs for Endurance Sports - Why Cluster DextrinTM and PalatinoseTM Beat Maltodextrin

Picture this:

You're 8 hours into an Ironman race. Your energy gels are making your stomach churn. Your blood sugar is on a roller coaster. Sound familiar?

Most endurance athletes fuel their bodies like they're putting out fires instead of keeping a steady flame burning. They reach for quick-fix maltodextrin gels that spike blood sugar fast, then crash hard. This creates a cycle of energy highs and lows that can ruin performance and make your gut feel terrible.

The truth is, your body can use carbs much more efficiently when you choose the right types. Research shows that slower-releasing carbs may help maintain steady energy levels while reducing digestive stress. This article will show you how different carbohydrate sources work in your body and which ones research suggests are best for long endurance events.

Quick Overview: Why Smarter Carb Sources Matter for Endurance

Main Benefit
Delivers steady, sustained energy without the blood sugar crashes often caused by simple sugars like maltodextrin.

Research Backing
Multiple studies show that combining glucose and fructose improves carbohydrate absorption rates, reduces gastrointestinal distress, and supports better endurance performance during prolonged exercise.

Best For
Ideal for endurance athletes competing or training for events longer than 2–3 hours. including Ironman, ultramarathons, long-distance cycling, or back-to-back training days.

Effective Dosage
Up to 90g of carbohydrate per hour from a mix of glucose and fructose is commonly used in high-intensity endurance protocols. This combination optimises absorption via dual transport pathways in the gut.

Onset & Duration
Expect a gradual and consistent energy release within 30–60 minutes of ingestion, helping to stabilise output and delay fatigue during extended efforts.

Safety & Tolerance
Well-tolerated when used at appropriate doses, especially with gradual adaptation. Athletes new to high-carb fueling should trial and adjust during training, not on race day.

The Science: How Your Body Uses Different Carbohydrates

Think of your digestive system like a multi-lane highway. When you consume glucose on its own, all the traffic gets funnelled into one lane — the SGLT1 and GLUT2 transporters. That bottleneck limits how much fuel can be absorbed and delivered to your working muscles.

Glucose is your body’s primary and fastest-acting carbohydrate. It has a glycemic index (GI) of 100 and gets absorbed rapidly through the small intestine. The absorption rate for glucose maxes out around 1.2–1.7 grams per minute, depending on individual tolerance and gut conditioning.

Fructose, on the other hand, travels a separate route. It uses GLUT2 and GLUT5 transporters and gets processed by the liver first via enzymes like fructokinase and aldolase B. This gives it a much slower absorption profile and a GI of around 23 — making it less likely to spike blood sugar or cause a crash.

The real benefit happens when you combine both glucose and fructose in the right ratios. By using multiple transport systems simultaneously, your body can absorb significantly more total carbohydrate — up to 90 grams per hour — without overwhelming any single pathway. This improves fueling efficiency while reducing the risk of GI issues during long training sessions or races.

The trick is to use carb sources that release glucose and fructose gradually, avoiding fast-spiking, single-source sugars like maltodextrin.

Note: Your gut has limits, but combining carbs the right way opens more "fuel lanes." Dual-source carbs (glucose + fructose) can significantly improve absorption rates, performance, and comfort during extended endurance efforts.

Key Carbohydrate Sources and Their Roles

Not all carbs behave the same once they enter your system. Choosing the right carbohydrate source (or combination) can mean the difference between sustained output and hitting the wall. Here's a breakdown of three commonly used carb types in endurance supplements and how they perform in the body.

Maltodextrin — The Problem Child
Maltodextrin is a group of short chains of glucose molecules (typically 3–17 units long) derived from starch. Once it reaches your small intestine, it’s broken down rapidly by digestive enzymes like α-amylase and maltase. These chains dissolve quickly into free glucose, leading to a fast spike in blood sugar and insulin.

• Glycemic Index (GI): 95–105
• Absorption rate: 1.2–1.7g per minute

This speed may seem ideal for energy, but it often causes problems during longer efforts. The rapid surge of glucose can lead to insulin spikes, followed by blood sugar crashes and digestive distress: especially during hot or high-intensity sessions.

Summary: Maltodextrin floods your system with sugar fast. It’s cheap and common, but not ideal for sustained performance or gut comfort.

Cluster Dextrin™ (Highly Branched Cyclic Dextrin) — The Steady Performer
Cluster Dextrin™ is engineered using special enzymes that restructure cornstarch into large, circular chains of 60–70 glucose units. These are bonded via strong α(1→6) linkages, which take significantly longer to digest compared to traditional carbs.

• GI: ~32
• Osmolality: Very low (9 mOsm per 10g/100ml)

This structure allows Cluster Dextrin™ to deliver glucose slowly and steadily, helping you avoid crashes while keeping blood sugar stable. Its ultra-low osmolality also means it clears the stomach quickly, reducing the chance of bloating or nausea — a major advantage during high-output endurance efforts.

Summary: Cluster Dextrin™ offers steady fuel with minimal GI distress, making it ideal for longer sessions or athletes with sensitive stomachs.

Palatinose™ (Isomaltulose) — The Balanced Choice
Palatinose™ is a disaccharide made from one glucose and one fructose molecule. It starts as sucrose (table sugar), but gets enzymatically restructured to contain strong α(1→6) bonds. These bonds break down about five times slower than regular sugar, releasing both glucose and fructose gradually over time.

• GI: ~32
• Structure: Glucose + Fructose in a 1:1 ratio

Because it delivers dual carbohydrates in equal parts, Palatinose™ allows your body to use multiple absorption pathways — maximising fuel uptake while keeping blood sugar stable. It’s a great option for long sessions requiring both efficiency and comfort.

Summary: Palatinose™ provides balanced, long-lasting energy and supports dual-carb absorption without the harsh spikes of traditional sugar.

Note: When it comes to endurance fueling, the type of carbohydrate you choose matters just as much as the amount. Combining low-GI, dual-pathway carbs like Cluster Dextrin™ and Palatinose™ gives you smoother energy delivery, less gut stress, and better performance — especially when you're pushing past the 2-hour mark.

Who Should Use Advanced Carbohydrate Sources

Not all endurance athletes need advanced carb formulas — but for those who do, the benefits are noticeable. These carbohydrate strategies are best suited to longer efforts and higher demands on fueling consistency, stomach comfort, and energy delivery.

Perfect for:

• Endurance athletes training or racing for longer than 2–3 hours

• Individuals who experience gut distress from standard maltodextrin-based gels

• Athletes aiming to maintain fat oxidation while still using carbs efficiently

• Anyone struggling with energy crashes or erratic pacing in long sessions

Best-use scenarios:

• Ironman triathlons and ultra-distance running events

• Multi-hour road cycling or mountain bike races

• Back-to-back long training days

• Competitive athletes who are “gel intolerant” or want a performance edge

Not ideal for:

• Short, high-intensity workouts under 90 minutes

• Athletes on tight budgets (premium carbs come at a higher cost)

• Those who already tolerate maltodextrin gels well with no issues

Note: Advanced carbs like Cluster Dextrin™ and Palatinose™ are best for serious endurance athletes who prioritise performance, gut comfort, and consistency over cost or convenience.

Practical Usage Tips for Endurance Fueling

Timing and Dosing

Start fueling around 30–60 minutes into your session — not when you start to fade. Using a 1:0.8 ratio of glucose to fructose has been shown to improve absorption and performance. This can be achieved by combining Cluster Dextrin™ (glucose-based) with Palatinose™ (balanced glucose and fructose).

• Begin with 60–70g of carbs per hour

• Work up to 90g per hour as your gut adapts

• Practice your strategy during long training sessions only — never test on race day

Note: The gut is trainable. Regular exposure to higher carb loads during long efforts is key to tolerance and performance.

Preparation Strategy

To optimise absorption, mix your carb sources in 500–600ml of water. This creates an isotonic solution (~300 mOsmol/kg), which allows for faster gastric emptying and more efficient delivery of fuel.

What to expect:
With consistent use, you should notice smoother energy within 30–60 minutes of consumption, fewer blood sugar spikes, and less bloating or nausea compared to traditional gels.

Note: Many athletes switching to dual-carb systems report more even pacing and less gut discomfort within just a few sessions.

Important Considerations

Cost Factor

Advanced carb sources like Cluster Dextrin™ and Palatinose™ are more expensive than standard carbs. However, for athletes doing long races or experiencing GI issues, the performance and comfort gains can be well worth the investment.

Individual Tolerance

Most people tolerate these carbs well, especially when introduced gradually. That said, any high-carb fueling strategy can cause issues if rushed or used improperly.

Note: Always trial your fueling plan multiple times in training before trusting it on race day.

Not a Magic Bullet

These carbs support energy and GI comfort, but they work best as part of a complete system that includes hydration, electrolytes, and — for some athletes — metabolic flexibility from fat-adaptation training.

Medical Considerations

Athletes with fructose malabsorption, diabetes, or related metabolic conditions should consult a qualified health provider before using high-carb fueling strategies.

Key takeaway: Science supports glucose-fructose combinations for improved absorption and reduced GI risk — but individual responses vary. Personal testing is essential.

Frequently Asked Questions

Q: Can I just use regular sugar instead?
Table sugar (sucrose) breaks down much faster than Palatinose™ or Cluster Dextrin™, often causing blood sugar spikes and crashes. While it’s cheaper, it won’t deliver the slow, steady energy release that makes specialty carbs ideal for endurance.

Q: How much should I take per hour?
Start with 60–70g of total carbohydrate per hour during long events. You can gradually increase to 90g as your tolerance improves, ideally using a blend of glucose and fructose sources. Always test during training.

Q: Do I need to use both Cluster Dextrin™ and Palatinose™?
Using both provides a more complete fueling profile: Cluster Dextrin™ offers steady glucose, while Palatinose™ delivers balanced glucose and fructose for dual absorption. That said, either one alone is a significant upgrade over maltodextrin.

Q: When will I notice the difference?
Most athletes feel a smoother energy profile and less gut distress within their first long training session using advanced carb sources. Over 2–3 weeks of consistent use, improvements in performance pacing and digestion become more obvious.

Research References:

O'Brien 2013 cycling trial demonstrating optimal glucose-fructose ratios for endurance
performance

Rowlands 2015: Fructose–Glucose Composite Carbohydrates and Endurance
Performance: Critical Review and Future Perspectives

König 2016: Substrate Utilization and Cycling Performance Following PalatinoseTM
Ingestion: A Randomized, Double-Blind, Controlled Trial

Wallis 2005: Oxidation of Combined Ingestion of Maltodextrins and Fructose during
Exercise

Hofman 2016: Nutrition, Health, and Regulatory Aspects of Digestible Maltodextrins

Stevenson 2017: A comparison of isomaltulose versus maltodextrin ingestion during
soccer-specific exercise

Sadowska 2020: Osmolality of Components and Their Application in the Design of
Functional Recovery Drinks

Glico Nutrition Co. Cluster DextrinTM technical documentation

Beneo GmbH PalatinoseTM research summary

Products like CarbMAX and PerforMAX from Strom Sports Nutrition incorporate these research-backed carbohydrate sources in formulations designed for optimal endurance performance.