A randomized, double-blind, placebo-controlled trial investigated the effects of a four-week probiotic intervention on mood in healthy adults. The study found that daily use of a multispecies probiotic significantly reduced self-reported negative mood, with effects observed after two weeks. Daily self-reports revealed changes not captured by traditional psychological questionnaires, indicating the potential role of probiotics in mood regulation in nonclinical populations.

Source: npj Mental Health Research