Probiotics & Brain Health: Can Yogurt Really Boost Your Mood?

observational-study PMID: 23474283

Quick Summary: A study found that women who ate a fermented milk product (like yogurt) with probiotics for a month showed changes in brain activity related to emotions and sensations. This suggests that probiotics might have a positive effect on brain function.

Does Yogurt Affect Your Brain?

This research looked at how eating a specific type of yogurt affects the brain. The study found that women who ate the yogurt with probiotics had different brain activity compared to those who didn't. Specifically, the changes were seen in brain areas that control emotions and how we feel things.

What The Research Found

Brain Activity Changes: The women who ate the probiotic yogurt showed a decrease in activity in a network of brain regions involved in processing emotions and sensations.

Midbrain Connection: The study also found changes in the way different parts of the brain communicated with each other, particularly in an area called the midbrain.

Study Details

Who was studied: 34 healthy women with no history of gut or mental health issues.

How long: 4 weeks (about a month).

What they took:

Group 1: Ate a fermented milk product (like yogurt) containing several probiotics, including Streptococcus thermophilus, twice a day.
Group 2: Ate a similar milk product without probiotics.
Group 3: No intervention.

What This Means For You

This research suggests that eating yogurt with probiotics, like Streptococcus thermophilus, might have a positive impact on your brain function. While more research is needed, it hints that probiotics could potentially influence your mood and how you experience sensations.

Consider adding probiotic-rich foods to your diet: Yogurt, kefir, and other fermented foods are good sources of probiotics.

Talk to your doctor: If you're considering probiotics for specific health concerns, it's always best to consult with a healthcare professional.

Study Limitations

It's important to remember these points:

Small study: The study only included a small number of women.

Multiple probiotics: The yogurt contained several different probiotics, so we can't say for sure that Streptococcus thermophilus was solely responsible for the effects.

No behavior changes measured: The study only looked at brain activity, not how people actually felt or behaved.

Only healthy women: The results may not apply to people with existing health conditions.

Key Findings

The study found that consuming a fermented milk product containing Streptococcus thermophilus and three other probiotics for 4 weeks reduced task-related brain activity in a network involving affective (emotion-processing), viscerosensory, and somatosensory cortices by 49% (cross-block covariance; P = 0.004). It also altered intrinsic connectivity in midbrain regions, suggesting a potential mechanism for the observed neural changes. These results indicate that probiotic-containing fermented milk may influence brain regions involved in emotional and sensory processing in healthy women.

Study Design

This was a randomized controlled observational study conducted in 2013. A total of 34 healthy women (age not specified) with no gastrointestinal or psychiatric symptoms were assigned to one of three groups:
1. FMPP group (n = 12): Consumed a fermented milk product with probiotics twice daily.
2. Control group (n = 11): Received a nonfermented milk product.
3. No intervention group (n = 13).
Brain activity was assessed via functional MRI (fMRI) before and after the 4-week intervention using an emotional faces attention task and resting-state connectivity analysis.

Dosage & Administration

Participants in the FMPP group consumed 125g of fermented milk twice daily for 4 weeks. The product contained four probiotic strains: Bifidobacterium animalis subsp. Lactis, Streptococcus thermophilus, Lactobacillus bulgaricus, and Lactococcus lactis subsp. Lactis. The control group received a nonfermented milk product with identical nutritional composition but no live probiotics.

Results & Efficacy

Task-related brain activity: FMPP intake was associated with a 49% reduction in cross-block covariance (a measure of neural network stability) in a distributed functional network (P = 0.004), including the prefrontal cortex, insula, and thalamus.
Resting-state connectivity: FMPP altered intrinsic midbrain connectivity, particularly affecting the periaqueductal gray and rostral pons.
Control groups: No significant changes were observed in the nonfermented milk or no-intervention groups.
The efficacy was specific to neural activity modulation, with no reported behavioral or psychological outcome measures (e.g., anxiety, mood) assessed.

Limitations

Small sample size: Only 12 participants in the FMPP group, limiting statistical power.
Short duration: Effects beyond 4 weeks were not evaluated.
Combination product: The fermented milk contained four probiotic strains, making it impossible to isolate the impact of S. thermophilus.
Population specificity: Results apply only to healthy women; no data on men, diseased populations, or long-term effects.
No microbiota analysis: The study did not confirm whether probiotics colonized the gut or altered microbiota composition.
Observational design: While randomized, the study lacked blinding and mechanistic insights (e.g., microbial translocation, metabolite analysis).

Clinical Relevance

This study suggests that regular consumption of a probiotic-containing fermented milk product may modulate brain activity in regions linked to emotion and sensory processing. However, the lack of behavioral outcomes and the use of a multi-strain formulation limit direct conclusions about S. thermophilus’s individual role. For supplement users, the findings support the potential of probiotic blends to influence central nervous system activity, but further research is needed to confirm these effects, determine clinical significance, and identify active components. The results are preliminary and should not be interpreted as evidence for therapeutic benefits in mental health or cognition.

Probiotics & Brain Health: Can Yogurt Really Boost Your Mood?