A study published in Brain, Behavior, and Immunity shows that taking a probiotic supplement may help boost mood.
Researchers from the Leiden Institute of Brain and Cognition at Leiden University in the Netherlands conducted a randomized controlled trial of 40 healthy young adults who didn't have mood disorders. Half took a powdered probiotic supplement, which they dissolved in water or milk and drank nightly for four weeks. The probiotic—Ecologic Barrier (Winclove BV)—contained eight different types of bacteria, including several strains of Bifidobacterium,Lactobacillus, and Lactococcus. Some research suggests that these types of bacteria may be effective at easing anxious and depressive symptoms. The other half of participants took a powdered placebo.
Before and after the trial, the researchers tested everyone on a depression sensitivity scale, which measured levels of cognitive reactivity to sad mood—a strong marker of depression. The researchers found no difference between the two groups before the intervention began. However, after four weeks, people who took the probiotic reported significantly less reactivity to sad mood than the control group—meaning that when they were put in a sad mood, they had fewer recurrent distressing or aggressive thoughts.
The researchers noted that more studies are needed to confirm this relationship. In addition, the researchers noted that they did not include dietary measures and did not control for consumption of other probiotic products or fermented foods. Therefore, they can't exclude that the consumption of probiotics was accompanied by spontaneous dietary changes that may have indirectly accounted for the effect.