Maltodextrin and the English Channel: Chemistry of Endurance Fuel

This episode of Chemistry World explores maltodextrin, a polysaccharide used as a high-energy fuel for endurance athletes crossing the English Channel. It details the compound’s quick dissolution in water, its hygroscopic properties, and how glucose units in short chains affect sweetness and solubility. The discussion also covers maltodextrin’s place in everyday foods, its digestion into glucose, and the nutrition trade-offs of high glycemic loads. The host and guest touch on contrasting fueling strategies, including the potential for mouth-rinse effects to counter mental fatigue, and close with reflections on future food science possibilities.

Introduction: Maltodextrin and the English Channel

The episode opens by linking a seemingly mundane food ingredient, maltodextrin, to one of the world’s most demanding endurance challenges, swimming the English Channel. The host uses a vivid, first-person account of pre-mixing the powder, its powdery form curling like smoke, and the chilling reality of a 21-mile open-water crossing that can take upwards of 14 hours. The narrative frames maltodextrin as a high-power energy source essential for prolonged performance, while also inviting a broader look at how chemistry underpins everyday nutrition and athletic endurance.

"Maltodextrin is a polysaccharide, consisting of ring-shaped glucose units bonded in chains up to 17 units long." - Anna Pshawski

Maltodextrin’s chemical nature

In this segment the chemistry of maltodextrin is unpacked. Maltodextrin is described as a polysaccharide formed from glucose units, with the chain length governing sweetness, solubility, and mouthfeel. Shorter chains produce sweeter flavors and higher solubility, a property food chemists exploit to fine-tune taste, texture, and shelf life. The discussion emphasizes how chain length modulation can alter not only sensory properties but also digestive behavior, since maltodextrin is rapidly absorbed as glucose in the small intestine. The guest explains how the polymer’s structural features make it a versatile ingredient across snacks, beverages, and low-fat products, while also becoming a focal point in debates about perceived sugar content in processed foods.

Endurance fueling and energy delivery

The core of the talk centers on maltodextrin as a high-energy fuel for endurance athletics. Its rapid digestion to glucose provides a quick energy surge that supports sustained muscle activity during long swims. The guest recalls the practical realities of fueling during the Channel crossing — frequent 1-hour and 0.5-hour fueling pauses, with a crew delivering warm maltodextrin beverages from a bottle on a string while the swimmer remains in the water. The glycemic impact is highlighted: high glycemic index means rapid blood glucose spikes, which can be followed by a crash, a common challenge for endurance athletes who rely on steady energy delivery. The discussion also notes alternative fueling strategies, including higher-fat or slower-release carbohydrate sources, to flatten the energy curve and potentially improve performance over very long efforts.

"Maltodextrin has a very high glycemic index, so every time I took a drink, it induced a spike in my blood glucose levels, flooding my muscles with much needed energy." - Anna Pshawski

Controversies and future directions in sports nutrition

The episode situates maltodextrin within a broader nutrition conversation. Its digestibility and rapid absorption make it a convenient energy carrier, but the high glycemic load raises questions about sustainable energy during extended exertion and the potential for glucose crashes. The host mentions that some practitioners prefer fat-rich foods or more complex carbohydrates to achieve a steadier energy release. A notable aside covers emerging research that simply rinsing the mouth with a caffeinated maltodextrin solution, without ingestion, can counteract mental fatigue, suggesting that even the oral-sensorial aspect of carbohydrate intake may influence performance and perception. This segues into a broader contemplation of how maltodextrin could find new roles in future food design and performance nutrition, balancing energy delivery with metabolic stability.

Reflections and a look ahead

The show closes by tying maltodextrin back to everyday food chemistry and its potential evolution. The host notes that maltodextrin will likely remain a ubiquitous tool in the food industry for texture and energy delivery, while ongoing research explores optimizing its metabolic and sensory profiles and leveraging its rapid digestibility in novel formats. The invitation to listeners to suggest compounds for future episodes anchors the program in community curiosity and ongoing discovery.