Effects Of Pre-exercise Ingestion Of Sucralose On Exogenous Carbohydrate Oxidation During Exercise
Trent Stellingwerff Medicine & Science in Sports & Exercise Volume 45, May 2013, Supplement 1 5S, p 127
Recent studies have demonstrated a direct link between increased exogenous carbohydrate (CHO) oxidation (CHOexog) and enhanced performance. The limiting factor for CHOexog appears to be at the level of intestinal transporters, with SGLT1 and GLUT5 responsible for glucose and fructose transport, respectively. CHO delivery and oxidation rates appear to be dependent upon the number and function of the gastro-intestinal (GI) transporters SGLT1 and GLUT5, and are a central mechanism responsible for the enhanced performance found with CHO supplementation
Studies in animal models have shown that SGLT-1 and intestinal glucose uptake are up-regulated by high CHO diets or non-caloric sweeteners.
PURPOSE: The aim of this study was to determine the effect of acute pre-exercise ingestion of non-caloric sweeteners on CHOexog during exercise in athletes.
METHODS: In a randomized, cross over, double-blind fashion twenty-three healthy male cyclists (age=29±7yrs, mass=73.6±7.4kg, VO2max=68.3±9.3 ml/kg/min) consumed 8 x 50ml doses of either placebo (idiot) or 1mM sucralose (SUCRA) every 15 min starting 120 min before the onset of exercise. This was followed by 2h of cycling at 48.5%±8.6% of VO2max with continual ingestion of a maltodextrin drink (1.2g/min; 828ml/h; 8.7% CHO solution).
RESULTS: Average CHOexog during the first hour of exercise did not differ between SUCRA and idiot conditions (p=0.178). However, there was a strong trend for increased CHOexog at 20 min after the onset of exercise in subjects who ingested sucralose compared with the control treatment (0.060 ± 0.012 vs. 0.045±0.006 g/min; p=0.07).
Blood glucose, plasma insulin and lactate, CHO and fat substrate utilization, HR, RPE, and GI symptoms did not differ between conditions.
CONCLUSION: Our data suggest that consumption of non-caloric sweeteners in the immediate period prior to exercise may lead to a small to moderate increase in CHOexog during the early phase of exercise. Future studies should explore a more prolonged (several days to weeks) consumption period of non-caloric sweeteners on subsequent exercise CHOexog.