Probiotics for Brain Health: Can They Boost Your Mood?

observational-study PMID: 32300799

Quick Summary: A recent study found that probiotics may improve mental flexibility and reduce stress in older adults. The research showed that taking specific probiotics for 12 weeks led to positive changes in the gut and brain health.

Probiotics and Brain Health: What the Research Found

This study looked at how probiotics affect the brain and mood of older adults. The researchers found that taking a daily probiotic supplement for three months:

Improved Mental Flexibility: Participants showed better results on tests of mental agility.

Reduced Stress: Stress levels decreased in those taking the probiotics.

Positive Gut Changes: The probiotics changed the types of bacteria in the gut, which is linked to brain health.

Study Details

Who was studied: 63 healthy adults, aged 65 and older, living in the community.

How long: The study lasted for 12 weeks (about 3 months).

What they took: Participants took either a daily probiotic supplement containing Bifidobacterium bifidum BGN4 and Bifidobacterium longum BORI, or a placebo (a "dummy" pill).

What This Means For You

This research suggests that probiotics could be a helpful addition to your routine if you're looking to support your brain health and manage stress as you age. Here's what you can consider:

Talk to your doctor: Before starting any new supplement, especially if you have existing health conditions.

Look for specific strains: The study used Bifidobacterium bifidum BGN4 and Bifidobacterium longum BORI. Not all probiotics are the same!

Consider your gut health: Probiotics work by changing the bacteria in your gut. A healthy gut is linked to a healthy brain.

Study Limitations

It's important to keep these points in mind:

Small study: The study only included 63 people, so more research is needed.

Short time frame: The study lasted only 3 months. We don't know the long-term effects.

Specific probiotics: The results apply only to the specific probiotic strains used in the study.

More research needed: While promising, this study doesn't prove that probiotics cause these benefits, only that they are linked.

Key Findings

Probiotic supplementation (Bifidobacterium bifidum BGN4 and Bifidobacterium longum BORI) for 12 weeks in healthy older adults (≥65 years) significantly reduced inflammation-associated gut bacteria (p < 0.05), improved mental flexibility (measured via the Consortium to Establish a Registry for Alzheimer's disease test), lowered stress scores (p < 0.05), and increased serum brain-derived neurotrophic factor (BDNF) levels (p < 0.05). A negative correlation between specific gut microbes (Eubacterium, Clostridiales) and BDNF was observed only in the probiotics group (Spearman’s RS = -0.37 to -0.39, p < 0.05).

Study Design

This was a randomized, double-blind, placebo-controlled multicenter trial conducted in 2021. Sixty-three community-dwelling older adults were assigned to either a placebo or probiotics group. The intervention lasted 12 weeks, with gut microbiota analyzed via 16S rRNA sequencing and cognitive/mood outcomes assessed using standardized tools (e.g., Geriatric Depression Scale, Positive Affect and Negative Affect Schedule).

Dosage & Administration

Participants consumed 1×10⁹ CFU/day of a probiotic blend containing B. bifidum BGN4 and B. longum BORI. The supplement was administered as freeze-dried powder in capsules, taken once daily. The placebo group received identical capsules without active bacteria.

Results & Efficacy

Gut microbiota: Probiotics reduced inflammation-linked bacterial abundance (e.g., Eubacterium, Clostridiales) compared to placebo (p < 0.05).
Cognitive function: Probiotics group showed greater improvement in mental flexibility (p < 0.05), though no significant differences were reported for overall cognition.
Mood: Stress scores decreased significantly in the probiotics group (p < 0.05), but no changes in depression or life satisfaction were observed.
BDNF: Serum BDNF levels increased in the probiotics group (vs. placebo, p < 0.05), with a negative correlation between BDNF and certain gut microbes (RS = -0.37 to -0.39).

Limitations

Small sample size: Only 63 participants (31 probiotics, 32 placebo), limiting generalizability.
Short duration: 12-week intervention may not capture long-term effects or sustainability of benefits.
Single probiotic combination: Results apply only to the specific strains tested (B. bifidum BGN4 and B. longum BORI).
Observational design: While an RCT, the study’s focus on correlations between gut microbes and BDNF does not establish causality.
Lack of mechanistic data: How probiotics influence BDNF or cognition remains unexplored.

Clinical Relevance

This trial suggests that probiotics may support mental flexibility and stress reduction in healthy older adults, potentially through gut microbiota modulation and increased BDNF. For supplement users, these findings highlight the value of strain-specific probiotics as part of a dietary strategy to maintain cognitive and emotional health in aging. However, the modest sample size and short duration warrant further research to confirm efficacy and explore optimal dosing, duration, and strain combinations. Clinicians might consider probiotics as a low-risk intervention for stress management in seniors, though individual variability in gut-brain axis responses should be acknowledged.

Note: The study did not report effect sizes or confidence intervals, focusing instead on p-values and correlation coefficients. Demographics (e.g., gender, baseline health metrics) were not detailed in the provided summary.