Jeukendrup 2017, training the gut for athletes

Review in Sports Medicine on adapting the gut to high carbohydrate intake. A high-carbohydrate diet raises the density and activity of intestinal SGLT1 transporters, increasing absorption capacity, and repeated exposure speeds gastric emptying and improves comfort. Adaptations appear within days and are substantial by about two weeks. A single carbohydrate saturates SGLT1 near 60 g/h; combining glucose with fructose raises usable intake beyond 90 g/h. Mechanistic and practical synthesis.