The effect of allulose, sucralose, and xylitol on Streptococcus mutans acid production

Abstract

Background: Caries is a bacterial infection driven by a dysbiotic biofilm enriched and fueled by sugar. Frequent consumption of sugar can impart negative health effects, including caries; thus, there is increased interest in identifying less cariogenic sugar substitutes. In this study, the authors investigated the in vitro pH shift by Streptococcus mutans planktonic cells in the presence of various sugars and sugar substitutes.

Methods: S mutans UA159 cells were suspended in a potassium chloride and magnesium chloride salt solution, and acidogenesis was determined by pH drop assay after the additions of sugars (sucrose, glucose, fructose) or sugar substitutes (allulose, sucralose, xylitol). The pH of S mutans cell suspensions was recorded at 10-minute intervals for 1 hour. Planktonic cells were then challenged with glucose and pH was monitored for an additional hour.

Results: All sugars resulted in an initial pH drop to 3.5. For xylitol and sucralose, the pH drop was minimal. Allulose initially dropped to a pH of 5.4 before leveling to 5.7. In subsequent glucose challenges, all S mutans cell suspensions with sugar substitutes dropped to pH 3.5.

Conclusions: Allulose, sucralose, and xylitol did not cause a pH drop as low as sugars, and were not considered cariogenic, except for allulose potentially causing root caries. Sugar substitutes were not able to prevent a pH drop to near 3.5 after the glucose challenge indicating these substitutes are not anticariogenic in the presence of glucose.

Keywords: Streptococcus mutans; acid drop assay; allulose; caries; sucralose; sugar; xylitol.

Figure 1

Results of pH drop assay for Streptococcus mutans planktonic cells in potassium chloride and magnesium chloride salt solution with sugars. A. Control S mutans cells only (no sugar added initially, with glucose added at 60 minutes to a final concentration of 1%). B. 50 mM glucose. C. 50 mM sucrose. D. 50 mM fructose. The results are from 5 independent experiments. B: Baseline.

Figure 2

Results of pH drop assay for Streptococcus mutans planktonic cells in potassium chloride and magnesium chloride salt solution with sugar substitutes. A. 50 mM allulose. B. 50mM xylitol. C. 50 mM sucralose. D. S mutans cells only control. Glucose was added after 60 minutes to a final concentration of 1%. The results are from 5 independent experiments. B: Baseline.

Figure 3

Results of pH drop assay for Streptococcus mutans planktonic cells in potassium chloride and magnesium chloride salt solution with 50 mM, 100 mM, or 1 M (15.2%) xylitol. Glucose was added after 60 minutes to a final concentration of 1%. The results are from 3 independent experiments.