Background and objectives: Safety is a key criterion for assessment of probiotics. The objective of this study was to evaluate safety of a new Iranian Lactobacillus paracasei IBRC-M 11110 strain as a candidate probiotic. Methods: Eighteen male and 18 female Wistar rats were divided into two experimental and a control group. The experimental groups received the bacterium at two doses of 6 × 108 CFU/day and 6× 109 CFU/day for 28 days through oral gavage. The control groups received normal saline. On day 29, blood, serum and tissue samples were taken for analysis. Results: Administration of the bacterium did not affect the general health and body weight of the rats during the study period. No significant change was observed in the blood parameters of rats in the experimental groups except for a significant decrease in mean corpuscular volume and mean corpuscular hemoglobin of male rats. Serum analysis showed a significant increase in the alanine transaminase and a significant decrease in aspartate transaminase in the experimental groups of male and female rats, respectively. In both male and female rats, a significant decrease in urea and a significant increase in creatinine were observed in the experimental groups. However, the above parameters were all within the normal range. Histopathological analysis of liver and kidney tissues also showed no abnormality. Conclusion: The results confirm that L. paracasei IBRC-M 11110 was safe in the subacute toxicity test in Wistar rats.
