A 90-day oral toxicity study of heat-treated Bifidobacterium longum CECT 7347 (ES1 HT) Postbiotic in rats

Probiotic organisms have a long history of safe consumption in foods and dietary supplements. Probiotics can be inactivated using a method such as heat treatment, creating more shelf stable, non-viable biotics, termed postbiotics. Heat-treated Bifidobacterium longum CECT 7347 (ES1 HT), a postbiotic derived from the probiotic strain B. longum CECT 7347 was tested in a 90-day toxicology study with 10 Wistar rats/sex/group using a study design adapted from the OECD test guideline for the 90-day repeated dose toxicology test in rodents (OECD TG 408). Heat-treated B. longum CECT 7347 (ES1 HT) was tested at a limit dose of 1000 mg/kg (5 x 10¹⁰ CFUeq/kg) body weight per day. Evaluated endpoints included detailed clinical observations, body weights, food/water consumption, grip strength, clinical chemistry, hematology, urinalysis, thyroid hormone analysis, organ weights, and histopathology. There were no treatment-related effects observed in this study. Based on the observed results, the NOAEL for heat-treated B. longum CECT 7347 (ES1 HT) in male and female Wistar rats following 90-days of repeated dose oral exposure was 5 x 10¹⁰ CFUeq/kg (1000 mg/kg limit dose) per day. These data support the safety of heat-treated B. longum CECT 7347 (ES1 HT) for food and dietary supplement applications.