Carbohydrates and Endurance Sports: The Science is Well-Established. The Opportunities Not.

The Unresolved Issue: Gastrointestinal Tolerance

Intestinal tolerance is the real battleground in nutrition formulation. Not the ratio of Carbohydrates — that’s a matter of chemistry. The problem is that the same supplementation protocol that works perfectly for one athlete causes bloating, cramps, or worse in another. Kleiner is explicit on this point: “There is real individual variation in gastric comfort, gastric emptying, and adaptation to glucose kinetics. We’re constantly conducting trials to figure out what works best for each athlete; there’s no one-size-fits-all solution.”

The race data confirms this in an uncomfortable way: at Ironman competitions, female athletes drop out significantly more often than men due to gastrointestinal problems. This is not because they are physiologically more fragile, but because most products and supplementation protocols were developed for male athletes and then applied to a different audience without the necessary adjustments.

This is a product gap, not just a research gap. Those who develop specific formulations for female endurance athletes — with dosages, formats, and tolerability profiles tailored to that physiology—are operating in a space that is still largely untapped.

The Gut Works Out: Implications for the Product and for Communication

Another factor that the market tends to oversimplify is Gut Training: the gut, like muscles, adapts to stimulation. Progressive exposure to increasing amounts of Carbohydrates during exercise increases the expression of intestinal transporters — SGLT1 and GLUT5 — thereby reducing gastrointestinal problems over time. An athlete who cannot tolerate 90 grams per hour today might be able to tolerate that amount after weeks of gradual exposure.

For a brand owner, this has a direct consequence, which Kleiner outlined at Vitafoods: “There’s a need for effective educational marketing aimed at trainers, dietitians, and others in similar fields.” The product alone isn’t enough—the usage protocol is part of its value. Those who succeed in building a system (product + consumer education + dosage progression) have a real competitive advantage over those who simply sell grams of carbohydrates per gel.

The European Regulatory Framework: A Story in Three Acts

Developers of Carbohydrate-based supplements for the European market need to be aware of a regulatory development that has unfolded over the course of seven years — and which today offers more opportunities than many industry players realize.

2011

EFSA issues a positive opinion on Carbohydrate-Electrolyte solutions for maintaining endurance performance. As a result, Carb+Electrolyte beverages may now carry performance claims on their labels in the EU market, provided they meet specific composition parameters (80–350 kcal/L from Carbohydrates, 20–50 mmol/L of Sodium, and an osmolarity between 200 and 330 mOsm/kg).

2014

The British Specialist Nutrition Association (BSNA) submitted a dossier seeking to extend the claim to Carbohydrate-only solutions — including gels — for maintaining endurance performance beyond 60 minutes. EFSA rejected it. This was not due to a lack of scientific evidence: Dr. Adam Carey, then president of the European Specialist Sports Nutrition Alliance (ESSNA), made this clear at the time: “We believe that EFSA reached this conclusion not because there is a lack of science supporting the claim, but because the type of evidence required by the approval process was not presented correctly.” The problem lay in the dossier—three meta-analyses without individual clinical trials, and a comparator (placebo: water/electrolytes) that was not sufficiently characterized — not in the science itself.

2018

Specialized Nutrition Europe (SNE) resubmits the dossier, this time via France and with evidence organized differently. EFSA issues a positive opinion: Carbohydrate solutions contribute to improved physical performance during high-intensity, long-duration exercise. The approved claim—which may be used on labels — reads: “Carbohydrate solutions may contribute to improved physical performance during high-intensity, long-duration exercise in healthy, trained adults.” Technical specifications: the solutions must provide between 30 and 60 grams of carbohydrates per hour, up to 90 g/hour if fructose constitutes about one-third of the mixture.

In summary

Today, anyone developing an energy gel for the European market has two viable options for performance claims — the Carbs+Electrolytes route (2011 claim: maintenance of endurance performance) and the Carbs Only route (2018 claim, improvement in performance during high-intensity, long-duration exercise). The lesson from 2014 remains valid for anyone navigating the EFSA process: science alone is not enough; the quality of the dossier is crucial.

Where Opportunities Arise

The market for endurance Carbohydrates is mature in the mainstream segment but offers specific opportunities for those entering with a differentiated formula. Kleiner identified these opportunities directly at Vitafoods 2026:

• Diverse Absorption Profiles — slow versus fast, sustained versus immediate. Not all sports require the same energy kinetics. A gel for road cycling and a gel for high-altitude trail running may have significantly different formulations.
• Underserved Segments — endurance athletes, athletes training at high altitudes or in extreme environments, and athletes over 50 with different recovery needs. All require specific formulation approaches.
• Functional Stacking — the combination of carbohydrates with Electrolytes, Caffeine, Adaptogens, or ingredients for muscle recovery opens up areas of development that are still largely unexplored in the gel segment.
• Format as a Differentiation Tool — powders, gels, liquids, and unflavored formats to counteract sensory overload at ultra-events. The choice of format isn’t just a logistical decision: it’s part of the value proposition.

As Kleiner summarized: “There are opportunities to learn from high-performance Carbohydrate products and to reach the broader active nutrition market.” The line between elite athletes and active everyday consumers is shifting —and those who can formulate products with scientific rigor for the former are well-equipped to serve the latter as well.

If you’re working on a formula for the endurance or active nutrition segment and want to understand where to position yourself between established science and opportunities that are still open, tell us about your project.