Addition of pectin-alginate to a carbohydrate beverage does not maintain gastrointestinal barrier function during exercise in hot-humid conditions better than carbohydrate ingestion alone

To compare the effects of consuming a 16% maltodextrin+fructose+pectin alginate (MAL+FRU+PEC+ALG) drink against a nutrient matched maltodextrin-fructose (MAL+FRU) drink on enterocyte damage and gastrointestinal permeability after cycling in hot and humid conditions. Fourteen recreational cyclists (7 men) completed three experimental trials in a randomized placebo-controlled design. Participants cycled for 90 min (45% VO2max) and completed a 15 min time-trial in hot (32°C) humid (70% relative humidity) conditions. Every 15-minutes cyclists consumed 143 mL of either (1) water; (2) MAL+FRU+PEC+ALG (90g CHO.hr/16% w/v), (3) - a ratio-matched MAL+FRU drink also (90g CHO.hr/16% w/v). Blood was sampled before and after exercise and gastrointestinal (GI) permeability determined by serum measurements of intestinal fatty acid-binding protein (IFABP) and the percent ratio of lactulose (5g) to rhamnose (2g) recovered in post-exercise urine. Compared to WATER, IFABP decreased by 349±67pg.mL-1 with MAL+FRU+PEC+ALG (p=0.007), and by 427±56pg.mL-1 with MAL+FRU (p=0.02). GI permeability was reduced in both the MAL+FRU+PEC+ALG (by 0.019±0.01, p = 0.0003) and MAL+FRU (by 0.014±0.01, p = 0.002) conditions relative to WATER. Both CHO beverages attenuated GI barrier damage to a similar extent relative to water. No metabolic, cardiovascular, thermoregulatory or performance differences were observed between the CHO beverages. Novelty bullets • Consumption of multiple-transportable CHO, with or without hydrogel properties, preserves GI barrier integrity and reduces enterocyte damage during prolonged cycling in hot-humid conditions.