Our understanding of the effect’s probiotics have on mental health is continually expanding. Research in the field of the gut-brain axis has linked psychiatric disorders, such as depression, to changes in the gastrointestinal microbiome. Several experimental methods have shown how antibiotic treatment, germ-free animal models and low diversity of faecal microbiota can negatively affect central nervous system function leading to symptoms of depression, anxiety and poor sleep.¹ Further, a growing body of evidence has shown that consumption of probiotics can improve symptoms associated with mood and anxiety disorders through activity of the gut-brain axis. However, up until now the effects of probiotics in patients diagnosed with major depressive disorder (MDD) had not been thoroughly examined.¹ 

Dosing recommendations

• Clinically effective dose: 
  • Multi-strain probiotic containing Lactobacillus helveticus (R0052), Bifidobacterium longum (R0175), Lactobacillus casei (R0215), and Bifidobacterium bifidum (R0071) at a dose of at least 3 billion colony forming units (CFUs) per day. ^1,2 
• Duration: 4-8 weeks. 
• Form: multistrain probiotic formulation. 
• Drug interactions: no known interactions, separate from medications by approximately two hours. 
• Safe dosing: upper level of safety for probiotics has not yet been established. 

In an open-label pilot study, 10 treatment-naïve patients with diagnosed MDD were given a probiotic supplement containing L. helveticus (R0052) and B. longum (R0175) at a dose of 3 billion CFUs per day for 8 weeks. Clinical symptoms of depression, anxiety, sleep, and anhedonia (inability to feel pleasure) were measured using a variety of clinical scales and self-report questionnaires. Data was collected at baseline, week 4 and week 8.¹ 

After 8 weeks of probiotic treatment participants reported significant improvements in clinical symptoms of depression, anhedonia (Figure 1) and anxiety (Figure 2), which were seen as early as week 4 and were sustained at week 8. Significant improvements in subjective sleep quality were observed by week 8 (Figure 2). No side effects or adverse effects were reported with probiotic supplementation.

Inhibition of two Clostridioides difficile (C. difficile) strains by multi-strain synbiotics 

Another important aspect of probiotic use is maintaining a healthy microbiome. One mechanism by which probiotics help to achieve this is via the inhibition of pathogenic bacteria, reducing the need for antibiotic therapy. This is of particular importance due to the growing issue of multidrug resistant bacteria such as Clostridioides (C.) difficile.² 

Administration of pro or synbiotics have been suggested for the management of diarrhoea, especially in cases caused by C. difficile. In an in vitro study by Sommermeyer et al. 2021, researches set out to investigate the growth inhibitory effects of a variety of probiotic supplements on quinolone-resistant and multidrug resistant C. difficile strains. Two different strains were examined to address the predominance of antibiotic resistance. 

Antimicrobial susceptibility of the C. difficile strains 

Antibiotic susceptibility testing revealed C. difficile (ATCC® 9689™) resistance against the quinolone’s ciprofloxacin and moxifloxacin while C. difficile (No. 644) exhibited a multidrug resistance profile against quinolones, clindamycin, erythromycin, and imipenem (Table 1).

Inhibition of C. difficile strains by various probiotic microorganisms 

Growth of both C. difficile strains were significantly inhibited by the multistrain synbiotic preparation containing L. casei (R0215), B. bifidum (R0071) and B. longum (R0175) [Figure 3. multistrain synbiotic B]. Inhibition of C. difficile by the multistrain synbiotics were significantly stronger (p <0.05) compared to all other tested products.²

Conclusion

 

Evidence continues to emerge on the beneficial effects of probiotic supplementation on a variety of health parameters including gastrointestinal health and mental wellbeing. The findings discussed suggest a role for specific probiotic strains in alleviating symptoms of depression and anxiety while improving sleep quality. Additional research proposes that multistrain synbiotics can be considered as an interventional option for diarrhoea caused by C. difficile. Taken together, this research helps solidify the use of probiotic supplementation containing a minimum of 3 billion CFUs per day to support multiple aspects of patient health including central nervous system function and reducing the incidence of gastrointestinal infections. 

References 

1. Wallace CJ, Milev RV. The efficacy, safety, and tolerability of probiotics on depression: Clinical results from an open-label pilot study. Front Psychiatry. 2021;12:132. 

2. Sommermeyer H, Pituch HM et al. Inhibition of Quinolone-and Multi-Drug-Resistant Clostridioides Difficile Strains by Multi Strain Synbiotics—An Option for Diarrhea Management in Nursing Facilities. Int J Environ Res Public Health. 2021;18(11):5871.