Understanding the differences between maltodextrin, fructose, and isomaltulose is essential to determine the best carbohydrate mix during exercise. The choice of these sources directly impacts absorption, energy delivery, and gastrointestinal comfort, which are key factors for performance in training sessions and endurance events.
What is maltodextrin and how it works during exercise
Maltodextrin is a glucose-derived carbohydrate widely used in sports nutrition due to its rapid digestion and absorption.
In the body, it is quickly converted into glucose and absorbed via the SGLT1 transporter, ensuring a rapid supply of energy. This characteristic is especially important during higher-intensity efforts, when energy demand is elevated.
In practical strategies, carbohydrate absorption via glucose or maltodextrin tends to reach around 60 g per hour, making it one of the main pillars in building an efficient carbohydrate mix.
The role of fructose in carbohydrate absorption
Fructose follows a different absorption pathway compared to maltodextrin, using the GLUT5 transporter. This difference allows for an increase in total carbohydrate absorption when both are consumed together.
The combination of maltodextrin and fructose can raise carbohydrate oxidation rates to values above 90 g per hour, potentially reaching up to 120 g per hour in trained athletes.
In addition to increasing energy availability, this carbohydrate mix tends to improve gastrointestinal tolerance, reducing the risk of discomfort during exercise.
Isomaltulose: more stable energy within the carbohydrate mix
Isomaltulose is a disaccharide composed of glucose and fructose, but with a more stable bond, resulting in slower digestion.
Within a carbohydrate mix, its main role is to provide a more gradual energy release, contributing to greater glycemic stability throughout exercise.
This can be especially beneficial during long training sessions, early stages of races, or strategies aimed at avoiding large fluctuations in energy levels.
Why combine maltodextrin, fructose, and isomaltulose
Combining these three carbohydrate sources allows for a more complete and efficient carbohydrate mix.
While maltodextrin provides rapid energy, fructose increases total absorption capacity, and isomaltulose contributes to a more sustained energy release. This integration supports both immediate energy availability and long-term energy maintenance during exercise.
Current protocols suggest ratios close to 2:1 between glucose-based carbohydrates and fructose, with individual variations depending on adaptation and nutritional strategy.
How to choose the best carbohydrate mix
The best carbohydrate mix depends on exercise duration, intensity, and individual tolerance.
Exercise duration and intensity
Longer and more intense efforts require strategies that allow for higher carbohydrate intake and absorption per hour.
Gastrointestinal tolerance
Gut adaptation is essential. Testing different combinations of maltodextrin, fructose, and isomaltulose during training helps reduce risks during competition.
Nutritional strategy
Training sessions are the ideal time to adjust the carbohydrate mix, both in total intake and in the ratio between sources.
Practical application for athletes
In practice, using a carbohydrate mix with maltodextrin, fructose, and isomaltulose allows for higher intake per hour with greater efficiency.
In endurance events, strategies reaching 90 to 120 g of carbohydrates per hour rely directly on the use of multiple sources. This approach supports performance by ensuring a continuous energy supply with a lower risk of gastrointestinal discomfort.
Conclusion
The differences between maltodextrin, fructose, and isomaltulose are directly related to how each carbohydrate is digested and absorbed.
Maltodextrin provides rapid energy, fructose increases total absorption capacity, and isomaltulose contributes to a more stable energy release. The strategic combination of these sources is what defines an efficient carbohydrate mix to sustain performance in endurance sports.
Reference
Jeukendrup, A. E. (2010). Carbohydrate intake during exercise and performance.
Available at: https://pubmed.ncbi.nlm.nih.gov/20574242/
