Probiotics bear no effect on students’ stress

A recent randomized, double-blinded, placebo-controlled study from New Zealand showed no significant benefit of probiotics on stress levels of undergraduate students.

A total of 391 students participated in the trial and were randomly assigned to receive either the probiotic L. rhamnosus HN001 (n=197) or placebo (n=194). Interventions were taken daily over the course of one semester. Psychological outcomes were measured using the Perceived Stress Scale, State Trait Anxiety Inventory, and the WHO-5.

At baseline, the median scores for the psychological outcomes were 21 for stress, 53 for anxiety, and 13 for wellbeing. No notable changes occurred over the course of the semester, with corresponding postintervention median scores of 18, 53, and 13.

Similarly, median change values in scores did not differ between groups. Stress scores, for instance, increased by a median of 2 points in both the placebo and probiotic groups (p=0.64). A median 0-point change was reported for anxiety and wellbeing scores in both groups, as well (p=0.42 and p=0.83, respectively).

“The potential impact of COVID-19 on this research requires discussion,” the researchers said, pointing out that government-mandated restrictions led to school closures and forced online learning for university students.

While the pandemic has been shown to pose a heavy mental burden on students, no such effect was reported in the present cohort. This could be attributed to New Zealand’s relative success against COVID-19, the researchers said.

“Students may have experienced a reduction in stress before their examinations due to a significant improvement in eliminating COVID-19 from the community that resulted in a shift down to Alert Level 1 during the semester,” they added.

Future studies assessing the efficacy of probiotics in boosting student wellbeing should account for the influences of the pandemic and related restrictions, according to the researchers.