Gut bacteria effect on brain function: Can probiotics help depression and anxiety?

Emerging studies have suggested that pathogenic and non-pathogenic gut bacteria might influence mood-related symptoms and even behavior in animals and humans. Recent studies illustrated  that gastrointestinal pathogens can communicate with the central nervous system and influence behavior associated with emotion, anxiety in particular, even at extremely low levels and in the absence of an immune response. Investigators have also shown that the administration of certain probiotic bacteria may support resilience and positively alter stress-related emotional behavior in animals under experimental stress. These probiotics organisms have the potential to influence mood-regulating systemic inflammatory cytokines, decrease oxidative stress and improve nutritional status when orally consumed

Patients with chronic fatigue syndrome (CFS) and other functional somatic disorders have alterations in the intestinal microbial flora. A recent study evaluated the effect of probiotic on the emotional symptoms of 39 patients with CFS. The patients were randomized to receive either 24 billion colony forming units of Lactobacillus casei strain Shirota (LcS) or a placebo daily for two months.  A significant rise in both Lactobacillus and Bifidobacteria in those taking the LcS, and there was also a significant decrease in anxiety symptoms among those taking the probiotic vs controls (p = 0.01). These results provide support to the presence of a gut-brain interface that may be mediated by microbes that reside or pass through the intestinal tract.

This preliminary research suggest the possibility that probiotics might influence anxiety and depression. The results of the present study should be a stimulus for further research about the utility of probiotics and their effects on anxiety and depression.