Safety evaluation of Bifidobacterium breve MCC1274 via oral toxicity tests in rats

In this study, the safety of Bifidobacterium breve MCC1274, a probiotic bifidobacterial strain, was assessed by single-dose and 90-day repeated-dose oral toxicity studies. In the single-dose oral toxicity assay using 6000 mg/kg of B. breve MCC1274 corresponding to 8.4 × 1011 colony-forming unit (CFU)/kg, mortality and adverse effects were not observed. Furthermore, the administration of 1000 mg/kg of B. breve MCC1274 by oral gavage in saline for 90 days did not induce any signs of toxicity, such as changes in clinical signs, body weight (BW), food consumption, ophthalmoscopy, urinalysis, hematology, blood chemistry, organ weight, gross pathology, and histopathology compared to the control group given cornstarch in saline (10/sex/group). The no-observed-adverse-effect-level of B. breve MCC1274 in the 90-day repeated-dose toxicity study was greater than 1000 mg/kg corresponding to 1.3 × 1011 CFU/kg. Based on the findings of this study, the acceptable daily intake of B. breve MCC1274 was calculated to be 1.3...