Probiotic therapy either with prebiotics or by itself may ease depression, according to a review of the data recently published in BMJ Nutrition Prevention & Health.1

However, the authors of the review noted that they were not able to determine the extent to which probiotic therapy could lessen symptoms of anxiety.1

Probiotics are foods containing bacteria that positively influence the gastrointestinal microbiome, whereas prebiotics are compounds that support the health of these bacteria.1

In light of the current understanding of the gut–brain axis (GBA) and its influence on our mental health, foods such as probiotics and prebiotics have been observed to have a positive effect on this relationship.1

According to the authors, the potential extent of the GBA on physiology and pathophysiology is too great to be assessed in a single study. However, they noted that due to the findings of prior studies that have focused on GBA’s effect on anxiety and depression, the current data on this area are more possible to assess.1,2

In the UK, 1.4 million people were referred for mental health issues between 2016 and 2017, showing the importance and prevalence of these issues today. Among these individuals, 53% had anxiety or stress related disorders, whereas 33% had depression.2

In order to investigate the efficacy of probiotic or pre-probiotic treatment in supporting such individuals, the researchers gathered 71 studies to assess for inclusion. Based on the criteria set by the researchers, only 7 of these studies met the requirements for the review. All 7 studies assessed at least 1 probiotic strain and 4 observed the effects of multiple strains.1,2

Among the selected studies, 12 probiotic strains were included, such as Lactobacillus acidophilus, Lactobacillus casei, and Bifidobacterium bifidium. Additionally, 1 study looked at probiotic treatment when combined with prebiotics, whereas another assessed prebiotics alone.1,2

Although there was variation in design, methods, and clinical considerations in the studies, all were able to demonstrate that probiotic supplements by themselves or with prebiotics were associated with significant reductions in symptoms of depression.1,2

All of the studies also showed that probiotic or combined pre-probiotic use was able to significantly reduce anxiety symptoms and/or clinically relevant changes in the biochemical measures of anxiety and/or depression.1,2

However, the researchers noted that limitations did exist in the review. The primary limitations of note were that all of the studies were rather short in duration and the number of participants in each was small.1,2

Due to these limitations, the authors acknowledged the need for larger studies that lasted for greater lengths of time before firm conclusions could be drawn regarding the overall effects of the treatment of probiotic or combined pre-probiotic in the management of anxiety and/or depression.1,2

Nevertheless, the authors suggested that the results of the review made clear that further investigation into the treatment was warranted.1,2

REFERENCES
  1. Noonan S, Zaveri M, Macaninch E, Martyn K. Food & mood: a review of supplementary prebiotic and probiotic interventions in the treatment of anxiety and depression in adults. BMJ Nutrition Prevention & Health. 2020;bmjnph-2019-000053. doi: 10.1136/bmjnph-2019-000053.
  2. Probiotics alone or combined with prebiotics may help ease depression [news release]. Eurekalert!; July 6, 2020. eurekalert.org/pub_releases/2020-07/b-pao070220.php. Accessed July 8, 2020.