Abstract
The purpose of this study was to evaluate the substrate oxidation of three commercially available, 14%-carbohydrate sports drinks with different compositions, osmolality, and pH for their impact on dental exposure to low pH. In a cross-over, randomized double-blinded design, 12 endurance athletes (age 31. 2 ± 7.7 years, V˙ O(2max) 65.6 ± 5.0 mL·kg(-1)) completed 180 min of cycling at 55% W(max). During the first 100 min of cycling, athletes consumed amylopectin starch (AP), maltodextrin+sucrose (MD+SUC), or maltodextrin+fructose hydrogel (MD+FRU) drinks providing 95 g carbohydrate·h(-1), followed by water intake only at 120 and 160 min. Fuel use was determined using indirect calorimetry and stable-isotope techniques. Additionally, dental biofilm pH was measured using the microtouch method in a subsample of participants (n = 6) during resting conditions before, and at different time intervals up to 45 min following a single bolus of drink. Exogenous carbohydrate oxidation (CHO(EXO)) during the 2nd hour of exercise was significantly (P < 0.05) different between all three drinks: MD+FRU (1.17 ± 0.17 g·min(-1)), MD+SUC (1.01 ± 0.13 g·min(-1)), and AP (0.84 ± 0.11 g·min(-1)). At the end of exercise, CHO(EXO) and blood glucose concentrations (3.54 ± 0.50, 4.07 ± 0.67, and 4.28 ± 0.47 mmol·L(-1), respectively) were significantly lower post MD+FRU consumption than post MD+SUC and AP consumption (P < 0.05). Biofilm acidogenicity at rest demonstrated a less pronounced pH fall for MD+FRU compared to the acidulant-containing MD+SUC and AP (P < 0.05). In conclusion, while total intake of MD+FRU showed signs of completed uptake before end of monitoring, this was less so for MD+SUC, and not at all the case for AP. Thus, this study showed that despite carbohydrates being encapsulated in a hydrogel, a higher CHO(EXO) was observed following MD+FRU drink ingestion compared to AP and MD+SUC consumption upon exposure to the acidic environment of the stomach. This finding may be related to the higher fructose content of the MD+FRU drink compared with the MD+SUC and AP drinks. Furthermore, a carbohydrate solution without added acidulants, which are commonly included in commercial sport drinks, may have less deleterious effects on oral health.