The relationship between mental health and the intestinal microbiome is a growing area of research interest. The intestinal microbiome’s influence goes beyond the gastrointestinal tract to also impact the central nervous system via the gut-brain axis.¹

Studies suggest that the gut microbiota exerts a strong influence on mental health and that manipulation of the microbiota with probiotics could be a viable treatment option.² Probiotics have been shown to alleviate and treat symptoms in individuals with clinically diagnosed mental health conditions.^1,2,3 However, many people experience mood imbalances without qualifying for a mental health diagnosis. A recent study investigated whether this group could also benefit from a daily probiotic for mood support.

Do Probiotics Support Mood in Healthy Individuals?

A double-blind, randomised, placebo-controlled trial¹ assessed the effects of a multi-strain probiotic supplement on symptoms of depression, anxiety, and stress in 49 healthy, college-aged students who had not been clinically diagnosed with a mood/psychological disorder.

Participants (aged 18-24 years) were divided into groups and randomly assigned to take a probiotic or placebo twice daily for six weeks. The prescribed probiotic was Winclove Ecologic® Barrier (2 g/day, 2.5 x 109 CFU/g) which contains nine bacterial strains: B. bifidum W23, B. lactis W51, B. lactis W52, L. acidophilus W22, L. brevis W63, L. casei W56, L. salivarius W24, Lc. Lactis W19, and L. lactis W58.

Symptoms of depression, anxiety and stress were measured using the DASS (Depression Anxiety Stress Scale) questionnaire at baseline and after 3 and 6 weeks of supplementation. Students consumed a standard American diet and did not make changes to diet or exercise habits during the study.

The Results Are In

Six weeks’ supplementation of the Ecologic® Barrier probiotic significantly (p<0.05) improved symptoms of depression, anxiety and stress in college students without a diagnosed mental health disorder. Similar improvements were also seen in the placebo group. The placebo effect has been commonly found in neurological conditions due to the expected benefits of seeking treatment.¹

Symptoms of depression, anxiety, and stress improved by 20.4% and 18.1% in the probiotic and placebo groups, respectively (baseline to post-test). Participants taking the probiotic showed acute, immediate improvement in total DASS scores and symptoms of stress during the first three weeks, as well as between three and six weeks. In contrast, while those in the placebo group showed similar improvements from baseline to three weeks, they did not significantly improve between weeks three to six.¹

Supporting Mood with Specific Multi-Strain Probiotics

The present study found that both probiotic and placebo supplementation improved mental health after six weeks. This supports earlier research using the same multi-strain probiotic which has been shown to be effective in alleviating symptoms of depression and anxiety.^2,4

A randomised, controlled trial (RCT) demonstrated that the Ecologic® Barrier probiotic had positive effects on symptoms of depression in healthy individuals who were not diagnosed with a depressive disorder (four weeks treatment).⁴ In another RCT of 71 patients with major depressive disorder taking Ecologic® Barrier probiotic (2 g twice daily for 8 weeks), results showed a significant reduction of cognitive reactivity to sad mood, particularly in mildly to moderately depressed patients.²

In an open label trial, patients with anxiety/depression and chronic gastrointestinal (GI) symptoms took the Ecologic® Barrier probiotic for 8 weeks. Results showed significant improvements in anxiety and depression symptoms, as well as significant decreases in GI complaints and improved quality of life.⁵

Brain-Gut-Microbiome Communication

The gut microbiota may mediate effects on mental health via the gut-brain axis.² This axis consists of bidirectional communication between the central and the enteric nervous system, linking emotional and cognitive centres of the brain with peripheral intestinal functions.⁶ The vagus nerve acts as the main signalling pathway between the gut lumen and the medulla oblongata, however there are many pathways of potential communication (see Figure 1).⁷

Figure 1. Bidirectional pathways of communication between the gut-microbiota and the brain.⁷ [CCK, cholecystokinin; GLP-1, glucagon-like peptide-1; IL, interleukin; PYY, peptide YY; TNF, tumor necrosis factor; SCFA, short-chain fatty acid.]

Leaky Gut and Systemic Inflammation Have a Role to Play

The intestinal barrier plays an important role in gut-brain communication. Numerous studies have shown the link between increased systemic inflammation and depression.² Dysregulation of the intestinal barrier causes proinflammatory cytokines (e.g. IL-6 and TNF-α) to be released from enterocytes. These can cross the blood-brain barrier and interfere with neurotransmitter production and impair functioning of the hypothalamic-pituitary-adrenal (HPA) axis, contributing to mood symptoms.^1,2

The Ecologic® Barrier probiotic has been shown to strengthen the intestinal barrier and reduce low grade inflammation.⁸ The influence of probiotics on the gut-brain axis may help explain the positive impacts on mood in the current study.

Probiotics Support Mood and Mental Health

This research review provides evidence that the multi-strain Ecologic® Barrier probiotic may improve symptoms of depression, anxiety and stress in healthy individuals not diagnosed with mood disorders.

Consuming a daily probiotic may be a supportive intervention to improve mood and overall mental health and wellbeing.

References

1. Ault DL, et al. Daily ingestion of a multi-strain probiotic improves symptoms of depression, anxiety and stress. JNES. 2023;2(1):1-21.
2. Chahwan B, Kwan S, Isik A, van Hemert S, Burke C, Roberts L. Gut feelings: A randomised, triple-blind, placebo-controlled trial of probiotics for depressive symptoms. J Affect Disord. 2019;253:317-326. doi:10.1016/j.jad.2019.04.097
3. Kazemi A, Noorbala AA, Azam K, Eskandari MH, Djafarian K. Effect of probiotic and prebiotic vs placebo on psychological outcomes in patients with major depressive disorder: A randomized clinical trial. Clin Nutr. 2019;38(2):522-528. doi:10.1016/j.clnu.2018.04.010
4. Steenbergen L, Sellaro R, van Hemert S, Bosch JA, Colzato LS. A randomized controlled trial to test the effect of multi-species probiotics on cognitive reactivity to sad mood. Brain Behav Immun. 2015;48:258-264. doi:10.1016/j.bbi.2015.04.003
5. Dao VH, Hoang LB, Trinh TO, Tran TTT, Dao VL. Psychobiotics for patients with chronic gastrointestinal disorders having anxiety or depression symptoms. J Multidiscip Healthc. 2021 Jun 10;14:1395-1402. doi: 10.2147/JMDH.S312316.
6. Carabotti M, Scirocco A, Maselli MA, Severi C. The gut-brain axis: interactions between enteric microbiota, central and enteric nervous systems. Ann Gastroenterol. 2015 Apr-Jun;28(2):203-209. 
7. Cryan JF, et al. The microbiota-gut-brain axis. Physiol Rev. 2019 Oct 1;99(4):1877-2013.
8. Van Hemert S, Ormel G. Influence of the multispecies probiotic Ecologic® BARRIER on parameters of intestinal barrier function. Food Nutr Sci. 2014;5:1739.