Fructose co-ingestion to increase carbohydrate availability in athletes.

Cas J Fuchs,Luc J C Van Loon,Javier T Gonzalez

doi:10.1113/jp277116

Cas J Fuchs, Luc J C Van Loon + Show 1 more

Open Access

https://doi.org/10.1113/jp277116

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Abstract

Carbohydrate availability is important to maximize endurance performance during prolonged bouts of moderate‐ to high‐intensity exercise as well as for acute post‐exercise recovery. The primary form of carbohydrates that are typically ingested during and after exercise are glucose (polymers). However, intestinal glucose absorption can be limited by the capacity of the intestinal glucose transport system (SGLT1). Intestinal fructose uptake is not regulated by the same transport system, as it largely depends on GLUT5 as opposed to SGLT1 transporters. Combining the intake of glucose plus fructose can further increase total exogenous carbohydrate availability and, as such, allow higher exogenous carbohydrate oxidation rates. Ingesting a mixture of both glucose and fructose can improve endurance exercise performance compared to equivalent amounts of glucose (polymers) only. Fructose co‐ingestion can also accelerate post‐exercise (liver) glycogen repletion rates, which may be relevant when rapid (<24 h) recovery is required. Furthermore, fructose co‐ingestion can lower gastrointestinal distress when relatively large amounts of carbohydrate (>1.2 g/kg/h) are ingested during post‐exercise recovery. In conclusion, combined ingestion of fructose with glucose may be preferred over the ingestion of glucose (polymers) only to help trained athletes maximize endurance performance during prolonged moderate‐ to high‐intensity exercise sessions and accelerate post‐exercise (liver) glycogen repletion.

Highlights

Carbohydrates are a major substrate source during prolonged moderate- to high-intensity exercise (Romijn et al 1993; van Loon et al 2001)
Since intestinal fructose absorption utilises a different transport mechanism, combining the ingestion of fructose and glucose takes advantage of both transport mechanisms, thereby increasing the total capacity for carbohydrate absorption. This can be beneficial during exercise to further increase exogenous carbohydrate oxidation rates and decrease gastrointestinal discomfort when large amounts of carbohydrates are ingested, thereby improving endurance exercise performance during prolonged moderate-to-high intensity exercise
When trying to maximize performance, well-trained athletes are advised to combine the ingestion of glucose and fructose at ingestion rates of 90 g/h during prolonged (>2.5 h) moderate-to-high intensity exercise

Summary

Introduction

Carbohydrates are a major substrate source during prolonged moderate- to high-intensity exercise (Romijn et al 1993; van Loon et al 2001). The main benefits of fructose co-ingestion (vs glucose (polymers) only) during exercise are due to increased exogenous (and total) carbohydrate oxidation rates and/or less gastrointestinal discomfort, rather than preventing muscle or liver glycogen depletion.

Results

Conclusion