Effects of Lactobacillus casei Shirota intake on caries risk in children

Yakult is a well-known probiotic beverage consisting of a single live bacterial species, Lactobacillus casei Shirota. However, the potential cariogenic/cariostatic effects of Yakult intake among children have not been studied yet. Hence, this study aimed to investigate the clinical effects of short-term Yakult intake on oral biofilm acidogenicity, cariogenic bacterial counts, and caries risk in children.

Eighteen children, 7-11 years of age, consumed standard Yakult daily for 7 days. Prior to and after intervention, functional oral biofilm acidogenicity characterized by the Stephan curve, Lactobacillus and Streptococcus mutans counts, and caries risk were determined.

Probiotic intervention demonstrated significant increase in minimum pH from 4.88 to 5.14 (P = 0.02), 18.2% reduction in area under the Stephen curve [area under the curve (AUC)], and 29.3% decrease in pH recovery time, although these two differences were not statistically significant. No difference was observed in S. mutans and Lactobacillus counts or caries risk after intervention (all P > 0.05). However, on subgroup analysis using "reduction of AUC" to separate "responders" from the "nonresponders", the significant cariostatic effects on oral biofilm acidogenicity, among "responders", were revealed by an increase in minimum pH (P = 0.005) and a reduction in pH recovery time (P = 0.003).

There may be a potential cariostatic effect of short-term Yakult intake in reducing functional biofilm acidogenicity in children with certain oral biofilm and risk profile. Further studies may be needed to validate this probiotic effect. Quality risk assessment may be critical prior to prescribing/recommending Yakult as an adjunct caries-preventive treatment for children.