A randomized clinical trial found daily supplementation with the probiotic Bifidobacterium animalis subsp lactis HN019 did not significantly improve constipation symptoms compared with a placebo. The study, published in JAMA Network Open, evaluated the effect of an 8-week probiotic intervention on CSBMs in adults with functional constipation.
Researchers conducted a triple-blind, placebo-controlled trial across five hospitals in Shanghai, China, from December 2020 to February 2022. Participants were randomized to receive either B lactis HN019 (7.0 × 10^9 colony-forming units [CFU] at study start, 4.69 × 10^9 CFU at study end) or placebo daily for eight weeks.
The primary outcome was the change in weekly CSBMs from baseline to the end of the study. At baseline, participants had a mean of 0.77 CSBMs per week. After eight weeks, the probiotic group showed an increase of 0.80 CSBMs per week, while the placebo group increased by 0.66 CSBMs per week. The difference between groups was not statistically significant.
Secondary outcomes including stool consistency, and degree of straining also showed no significant differences between the probiotic and placebo groups. However, abdominal pain and bloating reached statistical significance between the groups at the end of the study, with the probiotic group experiencing slightly lower symptoms. Fecal microbiota analysis revealed no significant changes in alpha or beta diversity between the study groups.
The trial enrolled healthy adults aged 18-70 years with functional constipation according to Rome III criteria and a body mass index <30.0. Participants were required to have ≤3 CSBMs per week at baseline. After a two-week run-in period, 229 eligible participants were randomized into the probiotic group and the placebo group. Participants recorded daily bowel habits and symptoms in electronic diaries. Fecal samples were collected at baseline and study end for microbiota analysis.
The study population had a low dietary fiber intake (mean 9 g/day), which may have contributed to constipation symptoms. A total of 11 treatment-emergent adverse events were reported: six in the probiotic group and five in the placebo group, but none were deemed related to the study treatment. No severe or serious adverse events occurred.
The authors noted several limitations, including potential impacts from COVID-19 restrictions in Shanghai during the study period. Additionally, the trial was conducted only in Shanghai, limiting its geographical scope and ethnic diversity.
Conflict of interest disclosures can be found in the study.
