Best Carbs for Endurance Sports - Why Cluster Dextrin and Palatinose 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 Facts
• Main benefit: Steady energy release without blood sugar spikes or crashes
• Research backing: Studies show glucose-fructose combinations can improve performance and reduce gut distress
• Best for: Endurance athletes doing events longer than 2-3 hours
• Dosage: Up to 90g per hour for mixed carb sources during intense endurance activity
The Science: How Your Body Uses Different Carbs
Think of your digestive system like a highway with multiple lanes. When you eat simple sugars like glucose, all the traffic tries to use just one lane - the SGLT1 and GLUT2 transporters. This creates a traffic jam that limits how much fuel gets through.
Glucose is the simplest carb your body uses. It has a glycemic index (GI) of 100, meaning it raises blood sugar as fast as possible. Your small intestine can absorb glucose at rates between 1.2-1.7 grams per minute through specific transport proteins called SGLT1 and GLUT2 transporters.
Fructose takes a different route entirely. It uses GLUT2 and GLUT5 transporters and gets processed by your liver first through enzymes called fructokinase, aldolase B, and triokinase. This slower process gives fructose a much lower GI of just 23. Your body can generally handle up to 30 grams of fructose per hour.
Here's where it gets interesting: When you combine glucose and fructose, you're using multiple transport systems at once. It's like opening up extra highway lanes. Research suggests this combination may allow your body to absorb up to 90 grams of carbs per hour instead of the usual 60 grams from glucose alone.
The key is choosing carb sources that release glucose and fructose slowly and steadily, rather than all at once.
Key Carbohydrate Sources and Their Roles
Maltodextrin
What it is: Short chains of 3-17 glucose molecules linked together
GI: 95-105 (very high)
Absorption rate: 1.2-1.7g per minute
Maltodextrin breaks down almost as fast as pure glucose once it hits your small intestine. The α(1→4) bonds that hold the glucose units together dissolve quickly when they meet enzymes called α-amylase and maltase. This creates rapid blood sugar spikes followed by crashes.
The downside: Forces your insulin system to work overtime and can cause gut distress during long events.
Cluster Dextrin™ (HBCD)
What it is: 60-70 glucose units arranged in branched, circular structures
GI: 32 (low-moderate)
Osmolality: Very low at just 9 mOsm per 10g/100ml
Cluster Dextrin™ is made by using special enzymes to restructure cornstarch. The process creates stronger α(1→6) bonds that take much longer to break down. This means glucose gets released slowly and steadily into your bloodstream.
Why it works: The branched structure slows digestion, reducing blood sugar spikes while providing sustained energy. Its extremely low osmolality means it empties from your stomach quickly, reducing bloating and nausea.
Palatinose™ (Isomaltulose)
What it is: One glucose and one fructose molecule bonded together
GI: 32 (low-moderate)
Processing: Made from sugar beets, restructured from sucrose
Palatinose™ starts as regular table sugar (sucrose) but gets restructured using enzymes. Instead of the weak α-(1→2) bonds in sucrose, Palatinose™ has stronger α-(1→6) bonds. These break down about 5 times slower than regular sugar, releasing both glucose and fructose gradually.
**The advantage**: Provides both glucose and fructose in a 1:1 ratio, utilizing multiple absorption pathways while maintaining steady blood sugar levels.
Who Should Use Advanced Carb Sources
Perfect for:
- Endurance athletes doing events over 2-3 hours
- People who experience gut distress from standard sports gels
- Athletes who want to maintain fat burning while still using carbs
- Anyone experiencing energy crashes during long training sessions
**Specific scenarios**:
- Ironman triathlons, ultramarathons, long cycling events
- Multi-hour training sessions
- Athletes who are "gel intolerant"
- Competitive endurance athletes seeking performance advantages
**Not ideal for**:
- Short, high-intensity workouts under 90 minutes
- Athletes on very tight budgets (these ingredients cost more)
- People who tolerate standard maltodextrin gels well
Practical Usage Tips for Endurance Fueling
Timing and Dosing:
Start fueling 30-60 minutes into your event, not when you feel tired. Research suggests the optimal ratio is about 1:0.8 glucose to fructose, which you can achieve by combining Cluster Dextrin™ with Palatinose™.
Begin with 60-70g per hour and gradually increase to 90g as your gut adapts. Practice this during training, never try new fueling strategies on race day.
Preparation Strategy:
Mix your carb sources in 500-600ml of water to achieve isotonic osmolality (around 300 mOsmol/kg). This matches your blood's natural concentration, allowing faster absorption.
What to expect: You should feel steady energy within 30-60 minutes without the sharp peaks and valleys of traditional gels. Many athletes report less gut distress and more sustainable energy levels.
Important: Always test your fueling strategy multiple times during long training sessions before using it in competition.
Frequently Asked Questions
Q: Can I just use regular table sugar instead of expensive specialty carbs?
A: Table sugar (sucrose) breaks down much faster than Palatinose™ or Cluster Dextrin™, creating the same blood sugar roller coaster as maltodextrin. While cheaper, it won't provide the steady energy release that makes these specialty carbs worth considering.
Q: How much should I use per hour during a long race?
A: Research suggests starting with 60-70g per hour and potentially working up to 90g per hour for very long events. This assumes a mixture of glucose and fructose sources. Always practice your dosing during training first.
Q: Do I need both Cluster Dextrin™ and Palatinose™ or can I use just one?
A: Using both provides the ideal combination of steady glucose release (from Cluster Dextrin™) and balanced glucose-fructose delivery (from Palatinose™). However, either one alone would be better than standard maltodextrin.
Q: How long before I notice a difference switching from regular gels?
A: Most athletes report steadier energy levels and less gut distress within their first long training session using these carbs. The full benefits become apparent after 2-3 weeks of consistent use during training.
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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 Palatinose™ 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 Dextrin™ technical documentation
- Beneo GmbH Palatinose™ research summary
Products like CarbMAX and PerforMAX from Strom Sports Nutrition incorporate these research-backed carbohydrate sources in formulations designed for optimal endurance performance.
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This content is for educational purposes only and does not intend to cure or diagnose disease, nor make any health claims. There is no intent to slander in any way, but rather produce an informed and accurate third party perspective on the product. Always consult your accredited medical professional before introducing a new supplement. This content is not to be copied or repurposed in any form without express permission from the author.
First published for stromsports.co.nz 31st July 2025.