Bowel function in runners after ingestion of sweeteners.

This study investigates the bowel function in outdoor runners drinking sweetened solutions both by determination of H2 in exhaled air and asking about intestinal discomfort. Twenty-two athletes with a mean age of 22 +/- 3 yrs, received 100 ml of a 10% water solution of saccharose, glucose, mannitol, and isomalt respectively, before a 60 min outdoor run training. The trial was repeated on a rest day, one week later. Samples of the exhaled air were obtained at time zero (basal) and then every 15 min for a period of 3 hrs after administration of the solutions. The H2 was detected by breath test. H2 excretion was lower during exercise. Suprabasal increments of breath hydrogen after saccharose load were significantly higher than after ingestion of mannitol (p < 0.05 between 1 and 3 hrs) and isomalt intake (p < 0.05 over 30 min). After glucose load, suprabasal increments of breath hydrogen were higher than after mannitol (p < 0.05 between 1 and 3 hrs) and isomalt (p < 0.001 between 1 and 3 hrs) ingestion. The intestinal discomfort in runners drinking sweetened solutions seems to be related to different bowel transit time.