Lactobacillus paracasei SD1, a novel probiotic, reduces mutans streptococci in human volunteers: a randomized placebo-controlled trial

Clin Oral Investig. 2014 Apr;18(3):857-62. doi: 10.1007/s00784-013-1057-5. Epub 2013 Jul 28.


Objectives: The present study investigates the effect of an oral Lactobacillus paracasei SD1 isolate on a number of salivary mutans streptococci, lactobacilli, and yeasts and to examine whether the strain could persist in the oral cavity after a short period of consumption. The potential side effect of the probiotic was also evaluated.

Material and methods: After informed consent, 40 healthy young adults were recruited and randomly assigned to either the test (A) or placebo (B) groups. Group A received milk powder contained L. paracasei SD1, and group B received standard milk powder once daily for 4 weeks. Salivary mutans streptococci, lactobacilli, and yeasts were enumerated using quantitative differential culture at the baseline and then once a week for 4 weeks after the administration period. The persistence of L. paracasei SD1 was also investigated using AP-PCR for the DNA fingerprinting.

Results: A statistically significant reduction in mutans streptococci counts occurred within group A compared to the baseline B (P < 0.05) along with a non-statistically significant reduction in yeast counts. A significant increase in lactobacilli numbers occurred in group A (P < 0.05), and the probiotic strain could be detected up to 4 weeks following cessation of dosing.

Conclusions: Our results demonstrate that short-term daily ingestion of the human-derived probiotic L. paracasei SD1 reduces the number of oral mutans streptococci.

Clinical relevance: L. paracasei SD1 may help to decrease the risk of dental caries, and this organism may be a useful probiotic organism for dairy products.

Publication types

  • Randomized Controlled Trial
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adult
  • Female
  • Humans
  • Lactobacillus / physiology*
  • Male
  • Placebos
  • Probiotics*
  • Streptococcus mutans / isolation & purification*
  • Young Adult


  • Placebos