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

Abstract

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. 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. 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. Our results demonstrate that short-term daily ingestion of the human-derived probiotic L. paracasei SD1 reduces the number of oral mutans streptococci. L. paracasei SD1 may help to decrease the risk of dental caries, and this organism may be a useful probiotic organism for dairy products.