This study examines the effect of popular sugar-containing carbonated beverages on the biochemical parameters of oral fluid. In an experiment conducted on a group of volunteers (n=8), the dynamics of pH and the enzymatic activity of α-amylase were assessed before and after consumption of Coca-Cola. A sharp decrease in pH to 4.62 and complete transient inactivation of the amyloclastic function of saliva were established. It was shown that the process of enzyme renaturation lags behind the rate of acid-base balance recovery, indicating a profound disruption of the primary stage of digestion.