Probiotic bacteriaIn a study published just last week in Brain, Behavior and Immunity, researchers found that multispecies probiotics have an effect on mood after four weeks of supplementation.

Hippocrates stated, “All disease begins in the gut,” and there is more and more evidence and research to support this. There is definitely a gut-brain relationship between nutrition and the gut microbiome, and how they support brain health and function.

The relationship between probiotics and mood

Probiotics are essential in improving digestion and immune function. In this study, researchers investigated whether the administration of a multispecies probiotic (containing Bifidobacterium bifidum,Bifidobacterium lactisLactobacillus acidophilusLactobacillus brevisLactobacillus caseiLactobacillus salivarius, and Lactococcus lactis) had an effect on rumination (i.e., recurrent thoughts about possible causes and consequences of a person’s distress). “Rumination is one of the most predictive vulnerability markers of depression,” says psychologist and study author Laura Steenbergen. “Persistent ruminative thoughts often precede and predict episodes of depression.”

This study was blind at three levels – group allocator, participants and outcome assessor – and was placebo-controlled, randomized, and had a pre- and post-intervention assessment design. It investigated the effect of multispecies probiotic intervention on cognitive reactivity to sad mood, as well as reported symptoms of depression and anxiety. Among the 40 participants, half of the people received a placebo powder, while the other half received a muiltispecies probiotic mixture. Participants came to the lab twice: once at the beginning of the study and again four weeks later. In both occasions they filled out a questionnaire indexing sensitivity (cognitive reactivity) to depression.

Results

Participants who received the multispecies probiotics showed significantly reduced ruminative thoughts compared to the participants who received the placebo powder. These results provide the first evidence that probiotics may help reduce negative thoughts associated with sad mood. In addition, this study provides information on a cognitive mechanism that may be responsible for the positive mood effects of probiotic supplementation. Thus, probiotic supplementation may serve as adjuvant or preventive therapy for depression.

Source: Laura Steenbergen, Roberta Sellaro, Saskia van Hemert, Jos A. Bosch, Lorenza S. Colzato. A randomized controlled trial to test the effect of multispecies probiotics on cognitive reactivity to sad mood. Brain, Behavior, and Immunity, 2015; DOI: 10.1016/j.bbi.2015.04.003