--- title: Recent Randomized Controlled Trial Explores Link Between the Gut-Brain Axis and Depression description: A randomized trial found high-dose probiotic supplementation for four weeks was linked to improved depression scores and increases in Lactobacillus. image: https://www.casi.org/hubfs/casi/archive/friblog_0.jpg --- An **educational publication of Designs for Health** [For Practitioners →](https://www.designsforhealth.com) [![casilogoresize2-2](https://www.casi.org/hubfs/casilogoresize2-2.png)](https://www.casi.org/) [Home](https://www.casi.org/) [Science Update](https://www.casi.org/articles/tag/science-update) [Research & Education](https://www.casi.org/articles/tag/research-education) [Archive](https://www.casi.org/articles/all) Search articles Search Science Update # Recent Randomized Controlled Trial Explores Link Between the Gut-Brain Axis and Depression CA Cory Ambrose, ND, MAT Jun 24, 2022 ![Recent Randomized Controlled Trial Explores Link Between the Gut-Brain Axis and Depression](https://www.casi.org/hs-fs/hubfs/casi/archive/friblog_0.jpg?width=960) The [gut-brain axis](https://pubmed.ncbi.nlm.nih.gov/33271426/) is a biochemical signaling pathway that’s believed to influence mood and brain functioning. [Depression](https://pubmed.ncbi.nlm.nih.gov/32130662/) is a complex mental health disorder that is the second leading cause of disability globally. Microbiota-driven inflammatory responses and other alterations to the [gut microbiome](https://pubmed.ncbi.nlm.nih.gov/33271426/) have been linked to mood-related changes and psychiatric disorders including depression. A recent [clinical trial](https://pubmed.ncbi.nlm.nih.gov/35654766/) explored the impact of high-dose, short-term probiotic supplementation on parameters related to depression.  A double-blind randomized controlled trial was recently published in *Translational Psychiatry* by [Schaub and colleagues](https://pubmed.ncbi.nlm.nih.gov/35654766/) who explored the potential relationship between probiotic supplementation and clinical outcomes related to depression. The study designers aimed to investigate if short-term high-dose probiotic supplementation could impact depressive symptoms and biomarkers related to the gut microbe and [neural changes](https://pubmed.ncbi.nlm.nih.gov/35654766/). Participants were randomized to a placebo or treatment group. The treatment consisted of daily supplementation for 4 weeks with probiotic strains containing 900 billion colony-forming units (CFUs). The probiotic strains were *Streptococcus thermophilus* NCIMB 30438, *Bifidobacterium breve* NCIMB 30441, *Bifidobacterium longum* NCIMB 30435 (re-classified as *B. lactis*), *Bifidobacterium infantis* NCIMB 30436 (re-classified as *B. lactis*), *Lactobacillus acidophilus* NCIMB 30442, *Lactobacillus plantarum* NCIMB 30437, *Lactobacillus paracasei* NCIMB 30439, and *Lactobacillus delbrueckii* subsp. *Bulgaricus* NCIMB 30440 (re-classified as *L. helveticus*). Major study parameters were assessed at baseline, week 4, and 4 weeks after treatment concluded (at week 8). Depressive symptoms were assessed using the Hamilton Depression Rating Scale (HAM-D).  [Study results](https://pubmed.ncbi.nlm.nih.gov/35654766/) indicate that increases in the genus *Lactobacillus* were linked with decreases in depressive symptoms in the treatment group. In addition, according to measurements in brain activity, supplementation with probiotics was shown to change the activation of the putamen during [emotional processing](https://pubmed.ncbi.nlm.nih.gov/35654766/) and the volume of gray matter in the calcarine sulcus. Also, HAM-D scores showed continuous improvement at the study terminus and again 4 weeks after treatment concluded.    The [authors’ overall conclusion](https://pubmed.ncbi.nlm.nih.gov/35654766/) was that probiotic supplementation in the treatment group was associated with improvements in self-reported depressive symptoms based on HAM-D scores as compared to a placebo. [Probiotic supplementation](https://pubmed.ncbi.nlm.nih.gov/35654766/) was also associated with improvements in biomarkers associated with gut microbiome health, including species richness. Limitations to the study include a relatively small sample size and study duration.   Researchers continue to elucidate the complexities of the gut-brain axis and the potential health-supportive role of probiotics. While more data are needed before clinical conclusions can be made, supplementation and diets rich in probiotics may influence the gut-brain axis and help support mood health.   On this page Share [LinkedIn](https://www.linkedin.com/shareArticle?mini=true&url=https%3A%2F%2Fwww.casi.org%2Farticles%2Frecent-randomized-controlled-trial-explores-link-between-the-gut-brain-axis-and-depression) [X](https://twitter.com/intent/tweet?url=https%3A%2F%2Fwww.casi.org%2Farticles%2Frecent-randomized-controlled-trial-explores-link-between-the-gut-brain-axis-and-depression&text=Recent+Randomized+Controlled+Trial+Explores+Link+Between+the+Gut-Brain+Axis+and+Depression) [Email](mailto:?subject=Recent%20Randomized%20Controlled%20Trial%20Explores%20Link%20Between%20the%20Gut-Brain%20Axis%20and%20Depression&body=https%3A%2F%2Fwww.casi.org%2Farticles%2Frecent-randomized-controlled-trial-explores-link-between-the-gut-brain-axis-and-depression) CA ### Cory Ambrose, ND, MAT Clinical Application ## Clinical Considerations in Practice In clinical practice, practitioners considering the topics discussed above may also weigh nutrient form, delivery and formulation, alongside individual patient variability. ### Practitioner Formulation Example ![Probiotic Supreme DF™](https://cdn.sanity.io/images/lemtscrs/production-www/8eabb991e312e44332a4b025d9bb2e57cf2c4d17-2000x2000.png?w=128&h=128&fit=max&auto=format) Probiotic Supreme DF™ 15 billion CFU multi-strain probiotic blend · Caplets [Explore Formulations →](https://www.designsforhealth.com/products/probiotic-supreme) ## Continue your research #### [Research & Education How Akkermansia Supports GLP-1 Production and Metabolic Function May 27, 2026](https://www.casi.org/articles/akkermansia-supports-glp-1-production-metabolic-function) #### [Research & Education Magnesium Glycinate Chelate Buffered: A Smart Approach to Magnesium Supplementation May 21, 2026](https://www.casi.org/articles/magnesium-glycinate-chelate-buffered-a-smart-approach-to-magnesium-supplementation) #### [Research & Education Overcoming the Anaerobic Barrier: A New Approach to Probiotic Manufacturing May 12, 2026](https://www.casi.org/articles/overcoming-the-anaerobic-barrier-a-new-approach-to-probiotic-manufacturing) #### [Science Update A Case Report on a Functional GI Testing Protocol in a 35-Year-Old Female with Gastrointestinal and Joint Discomfort May 07, 2026](https://www.casi.org/articles/a-case-report-on-a-functional-gi-testing-protocol-in-a-35-year-old-female-with-gastrointestinal-and-joint-discomfort) ![casilogoresize2-2](https://www.casi.org/hubfs/casilogoresize2-2.png) An educational publication of [**Designs for Health**](https://www.designsforhealth.com). 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