Impact of an aspartame‐containing diet soft drink on postprandial metabolism

Abstract

ObjectiveNon‐nutritive sweeteners (NNS) are widely used to lower daily caloric intake. However, controversy exists concerning possible metabolic effects of NNS. We hypothesized that Diet Coke, containing aspartame, differentially affects postprandial metabolism compared to a sugar‐sweetened beverage (Coke), but not water when co‐ingested with a mixed meal.MethodsSix healthy lean (26±1% body fat) males aged 20–26 yrs completed three separate tests consisting of a mixed meal (0.4g fat, 0.8g carbohydrates, and 0.3g protein/kg FFM) with the addition of 20oz of Coca‐Cola (CC: 787±49kcal), Diet Coke (NNS: 547±49kcal), or water (CON: 547±49kcal). Resting metabolic rate was measured via indirect calorimetry and blood samples were obtained immediately before, 5, 10 and 30 min, and 1, 2 and 3 hours after meal and beverage ingestion.ResultsThere was a significant main effect of treatment on fat oxidation rate, with post hoc analysis indicating differences between effect between CC and CON (P < 0.001), and CC and NNS (P = 0.012). For all measures of fat oxidation, including total fat oxidized, area under the fat oxidation curve (AUC), and total postprandial fat oxidized, NNS and CON were significantly higher compared to CC (P < 0.05). Additionally, there was a significant main effect of treatment on the rate of carbohydrate oxidation, with post hoc testing indicating differences between CC and CON (P < 0.001), and CC and NNS (P = 0.023). All measures of carbohydrate oxidation, including total carbohydrate oxidized, carbohydrate oxidation AUC, and total postprandial carbohydrate oxidized were significantly lower during NNS and CON treatments compared to CC (P < 0.05), with no differences between NNS and CON. There were no significant differences among treatments in glucose concentrations.ConclusionDiet Coke does not impact postprandial metabolism, whereas Coca‐Cola suppresses fat oxidation and increases carbohydrate oxidation compared to Diet Coke and water.Support or Funding InformationR.C.P. was support by the University of Georgia Graduate School Georgia Research Education Award Traineeship Follows Program