The effect of Yakult on oral health of healthy denture-wearers

Methods: Eight denture-wearers undertook a 7-week trial comprising 3 phases: one baseline; 4-week consumption of 65 ml bottle of Yakult Original per day, each containing a minimum of 3.0 x 10¹⁰ viable LcS; followed by 2-week washout period. The viability of probiotic strain LcS, total facultative and obligate Gram-negative anaerobic species, acid-producing organisms, Streptococcus mutans species and yeast in saliva, dorsal tongue and denture plaque were assessed using a range of solid selective and indicator media. Questionnaires were used to explore participants' denture cleaning habits (general questionnaire) and the impact of wearing dentures on their quality of life and well-being (modified OHIP-14) prior to and after the study completion.

Results: One male and 6 female denture-wearers completed the trial. No significant effect after four weeks of probiotic ingestion on resident microbial populations was found. LcS was temporarily present in saliva, tongue and denture plaque during the consumption phase and for up to 7 weeks of washout, but at relatively low numbers. Presence of LcS did not affect the occurrence and viability of Candida spp. Participants presented a good general knowledge of denture hygiene, and their post-study responses to modified OHIP-14 questionnaires improved.

Conclusion: Four-week consumption of Yakult Original had no effect on resident microflora in healthy denture-wearers despite temporary presence of LcS in the oral cavity. Future studies should focus on subjects at risk of oral infection, where increased proportions of ill-defined flora might be affected by consumption of Yakult.