Do Probiotics Affect Mental Health?

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Written by Consensus
5 min read

Do probiotics affect mental health?

Check out this answer from Consensus:

Overall, the evidence suggests that probiotics can have a positive impact on mental health, particularly in reducing symptoms of depression and anxiety and improving cognitive function and mood. These benefits are likely mediated through reductions in inflammation and oxidative stress. However, the extent of these effects can vary depending on the population studied and the specific probiotic strains used. Further research is needed to clarify the clinical significance and optimize the use of probiotics for mental health.

The potential impact of probiotics on mental health has garnered significant interest in recent years. Probiotics, which are live microorganisms that provide health benefits when consumed in adequate amounts, are thought to influence mental health through the gut-brain axis. This synthesis examines the evidence from multiple research studies to determine whether probiotics can affect mental health outcomes such as depression, anxiety, and cognitive function.

Key Insights

  • Improvement in Depression and Anxiety Symptoms:
    • Probiotic supplementation has been shown to reduce symptoms of depression and anxiety in various populations, including patients with psychiatric disorders and healthy individuals .
    • Specific studies have demonstrated significant reductions in depression scores (e.g., Hamilton Depression Rating Scale) and anxiety symptoms following probiotic intake .
  • Impact on Cognitive Function and Mood:
    • Probiotics have been found to improve cognitive function and mood in older adults, with notable improvements in mental flexibility and stress reduction.
    • Some studies suggest that probiotics can enhance psychological well-being and reduce psychiatric distress, although the effects may be modest.
  • Reduction in Inflammatory and Oxidative Stress Markers:
    • Probiotic supplementation has been associated with a decrease in biomarkers of inflammation (e.g., C-reactive protein, interleukin-10) and oxidative stress (e.g., malondialdehyde) .
    • These reductions in inflammatory and oxidative stress markers may contribute to the observed improvements in mental health .
  • Effectiveness in Specific Populations:
    • Probiotics have shown beneficial effects on mental health parameters in women with polycystic ovary syndrome (PCOS) when co-supplemented with vitamin D or selenium .
    • In perinatal women, probiotics have been found to reduce anxiety symptoms, although the evidence for reducing depression is less conclusive.
  • Variability in Results:
    • While many studies report positive effects of probiotics on mental health, some meta-analyses indicate that the overall impact may be small or not statistically significant, particularly in healthy individuals .
    • Differences in probiotic strains, dosages, and study designs contribute to the variability in findings.

 

 

Do probiotics affect mental health?

Hannah Wardill has answered Uncertain

An expert from University of Adelaide in Gastroenterology, Microbiome

I would absolutely like to echo the answers of the other experts here, reiterating that while there is a convincing body of evidence that has been accumulated from animal studies, our understanding of this complex phenomenon in humans remains a little superficial. A meta-analysis was recently published on this topic, which included 19 individual studies of healthy individuals as well as people with a variety of mood disturbances, including major depressive disorder.

They found that in the healthy population, there was no overall significance for the use of probiotics in elevating mood. Similarly, in all the mood disturbances evaluated there was no benefit seen with probiotics. However in people with major depressive disorder, probiotics had a significant benefit. In all cases, probiotic formulations with multiple strains had the best efficacy, suggesting that it may not all be about a specific microbe, but rather having a diverse and thriving microbial community to support brain health. As such, eating a balanced diet full of fruit and vegetables and combining it with the psychosocial benefit of exercise may be a more holistic way of improving mood.

Meta-analysis: https://www.ncbi.nlm.nih.gov/pubmed/31563280

 

Do probiotics affect mental health?

Paul Forsythe has answered Unlikely

An expert from McMaster University in Immunology, Behavioural Science

The idea that probiotics might affect mental health comes from animal studies which have demonstrated that certain strains of bacteria can modulate the behaviour of mice and rats in a similar way to known antidepressant and anxiolytic drugs 10.1186/s12916-016-0604-8;  10.1111/bph.14127. Similarly, there is evidence from animal studies that probiotics can protect against detrimental effects of early-life challenges on neurodevelopment 10.1016/j.neuroscience.2018.01.060 . However, to date, there is no convincing evidence to suggest that probiotics can improve any mental health disorder in humans.

 

Do probiotics affect mental health?

In my view, this is an interesting topic that deserves far more research before we can draw a conclusion. Preclinical studies and several anecdotal reports in patients show that there could be a link between mental health and dysbiosis, and therefore probiotics (but also prebiotics, see doi: 10.1136/gpsych-2019-100056) might be able to equilibrate gut microbiota, mucosal barrier and improve intestinal health. This may reduce the level of systemic inflammation that might contribute to mental disorders. However, good quality clinical studies are still scarce, with low number of patients, and many confounders.

 

Do probiotics affect mental health?

Possibly, but we have no definitive studies.  All the studies so far published are small scale.

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