Probiotics for mood
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Probiotics for Mood: A Comprehensive Review
Introduction to Probiotics and Mood
Probiotics, live microorganisms that provide health benefits when consumed in adequate amounts, have been increasingly studied for their potential impact on mental health. The gut-brain axis, a bidirectional communication system between the gut microbiota and the brain, is believed to play a crucial role in this interaction. This article synthesizes current research on the effects of probiotics on mood, particularly focusing on depression and anxiety.
Probiotics and Depression
Clinical Trials and Meta-Analyses
Several studies have investigated the impact of probiotics on depressive symptoms. A meta-analysis of 10 clinical trials involving 1,349 patients found no significant difference in mood between the probiotic and placebo groups overall. However, subgroup analysis revealed significant improvements in individuals with mild to moderate depressive symptoms 2. Another meta-analysis of 34 controlled clinical trials reported small but significant effects of probiotics on depression, with a more substantial impact observed in clinical samples compared to community samples 7.
Specific Strains and Their Effects
Different strains of probiotics have been tested for their efficacy in alleviating depressive symptoms. For instance, a study involving treatment-naïve patients with Major Depressive Disorder (MDD) showed significant improvements in depressive symptoms after an 8-week supplementation with Lactobacillus helveticus R0052 and Bifidobacterium longum R0175 6. Another study found that a multispecies probiotic reduced depression scores by 50% in individuals with moderate depression 5.
Probiotics and Anxiety
General Findings
The relationship between probiotics and anxiety has also been explored, though the results are mixed. A systematic review and meta-analysis of controlled clinical trials found that probiotics could significantly reduce depression scores but did not show a significant effect on anxiety scores 8. Similarly, another meta-analysis reported small but significant effects of probiotics on anxiety, with a more pronounced effect in clinical samples 7.
Stress and Cognitive Reactivity
Probiotics have been shown to reduce cognitive reactivity to sad mood, a marker of vulnerability to depression. A study involving healthy participants found that a 4-week multispecies probiotic intervention significantly reduced overall cognitive reactivity to sad mood, particularly rumination and aggressive thoughts 4. Additionally, probiotics have been associated with improved mood and reduced stress in healthy individuals under stress conditions 10.
Probiotics and Overall Psychological Well-being
Mood and Sleep Quality
Probiotics have been linked to improvements in various aspects of psychological well-being, including mood and sleep quality. A study involving healthy volunteers reported significant improvements in mood, including reductions in depressive mood state, anger, and fatigue, as well as enhanced sleep quality after 6 weeks of probiotic supplementation 3. Another study found that probiotics promoted mental flexibility and alleviated stress in healthy older adults, along with changes in gut microbiota 1.
Emotional Processing
Probiotics may also influence emotional processing. A study on depressed volunteers found that probiotic intake increased accuracy in identifying emotional expressions and reduced reward learning, suggesting a unique mechanism of action compared to conventional antidepressants 5.
Conclusion
The current body of research suggests that probiotics have the potential to improve mood, particularly in individuals with mild to moderate depressive symptoms. While the effects on anxiety are less clear, probiotics appear to offer some benefits in reducing stress and improving overall psychological well-being. However, more high-quality, large-scale studies are needed to fully understand the therapeutic potential of probiotics for mood disorders.
Sources and full results
Most relevant research papers on this topic
Probiotic Supplementation Improves Cognitive Function and Mood with Changes in Gut Microbiota in Community-Dwelling Older Adults: A Randomized, Double-Blind, Placebo-Controlled, Multicenter Trial
Probiotics improve mental flexibility and reduce stress in healthy older adults, while also causing changes in gut microbiota.
RCT
Highly CitedA meta-analysis of the use of probiotics to alleviate depressive symptoms.
Probiotic supplementation has an overall insignificant effect on mood, with potential improvements for individuals with mild to moderate depressive symptoms.
Meta-Analysis
Rigorous JournalHighly CitedEffects of Probiotics on Cognitive Reactivity, Mood, and Sleep Quality
Probiotics administration improves psychological well-being by reducing depressive mood state, anger, and fatigue, and improving sleep quality in healthy individuals.
RCTHighly CitedA randomized controlled trial to test the effect of multispecies probiotics on cognitive reactivity to sad mood
Probiotic supplementation may help reduce negative thoughts associated with sad mood, warranting further research as a potential preventive strategy for depression.
RCTRigorous JournalHighly CitedMultispecies probiotic administration reduces emotional salience and improves mood in subjects with moderate depression: a randomised, double-blind, placebo-controlled study
Probiotic supplementation improves mood and reduces emotional salience in individuals with moderate depression, but its effects on emotional processing and cognition remain unclear.
RCTRigorous JournalThe Efficacy, Safety, and Tolerability of Probiotics on Depression: Clinical Results From an Open-Label Pilot Study
Probiotics can improve depression symptoms and sleep quality in treatment-nave, moderately depressed patients without causing side effects.
RCTHighly CitedPrebiotics and probiotics for depression and anxiety: A systematic review and meta-analysis of controlled clinical trials
Probiotics show small but significant effects on depression and anxiety, with larger effects observed in clinical/medical samples.
Meta-AnalysisHighly CitedEffects of Probiotics on Depressive or Anxiety Variables in Healthy Participants Under Stress Conditions or With a Depressive or Anxiety Diagnosis: A Meta-Analysis of Randomized Controlled Trials
Probiotics may alleviate depressive symptoms in patients with depression or anxiety disorders, but their effectiveness in reducing anxiety remains insufficient.
Meta-AnalysisHighly CitedEffect of Probiotics on Psychiatric Symptoms and Central Nervous System Functions in Human Health and Disease: A Systematic Review and Meta-Analysis
Probiotics show potential in improving psychiatric symptoms and central nervous system function, but more research is needed to determine their specific effects and potential benefits.
Meta-Analysis
Very Rigorous JournalProbiotics and Subclinical Psychological Symptoms in Healthy Participants: A Systematic Review and Meta-Analysis.
Probiotic consumption may have a positive effect on psychological symptoms of depression, anxiety, and perceived stress in healthy human volunteers.
Meta-AnalysisHighly Cited