This Specific Probiotic Improves Mood & Sleep In Older Adults, New Study Finds
Gut health and brain health are closely connected (thanks to the gut-brain axis). Research continues to show that a healthy and diverse microbiome is linked to better mental health, whereas dysbiosis (an imbalance of good to bad bacteria) can negatively impact your mood. Now, scientists are zeroing in on which specific probiotic strains might actually move the needle.
A new clinical trial1 tested one lesser-known strain in older adults and found measurable improvements in mood, sleep, and digestion after just eight weeks. Here's what you need to know.
About the study
The goal of this trial was to determine whether supplementing with Pediococcus acidilactici PA53 could improve emotional well-being in healthy older adults by shifting their gut microbiota. This strain was selected for its ability to survive stomach acid and colonize the gut, advantages over more commonly studied probiotics like Lactobacillus or Bifidobacterium, particularly in aging populations where microbial diversity naturally declines.
Seventy-five healthy adults aged 55 to 70 were randomized into a probiotic group (30 billion CFU of PA53 a day) or a placebo group for eight weeks. Researchers measured gut bacteria composition, blood inflammatory markers, and validated scales for happiness, sleep, GI symptoms, and stress at baseline and week 8.
Eight weeks of supplementation improved mood, sleep, and gut comfort
Participants taking PA53 reported feeling measurably happier (12.7% improvement on a validated happiness scale). Sleep quality improved by 23%, with participants falling asleep more easily and sleeping more soundly. Digestive comfort improved too, with GI symptom scores dropping by nearly 10%, and stool consistency moved toward a healthier range.
Stress scores trended downward in the probiotic group, but the change wasn't statistically significant on its own (though the group did perform significantly better than placebo on this measure).
On the inflammation front, two markers tied to chronic low-grade inflammation (IL-6 and TNF-α) dropped significantly, while IL-25, a cytokine that helps regulate immune balance, increased. Several beneficial gut bacteria also grew meaningfully, including genera associated with gut barrier health and anti-inflammatory activity.
Why the gut-brain connection may explain these results
The mood and sleep improvements tracked closely with the microbiome and inflammatory changes, pointing to the gut-brain connection as the likely mechanism.
PA53 appears to strengthen the intestinal lining by supporting tight junction proteins, the structures that keep inflammatory compounds from leaking into the bloodstream. The strain also produces short-chain fatty acids and converts tryptophan into compounds that can cross the blood-brain barrier and help reduce neuroinflammation.
The study's authors note these are early findings, and more research is needed to confirm long-term effects.
RELATED READ: 2 Easy Daily Habits That Support Your Gut Microbiome
What to look for in a probiotic if gut-brain health is your goal
PA53 isn't widely available as a standalone supplement yet, but the findings offer useful guidance:
- Strain specificity matters: The benefits of probiotics are strain specific. Look for products that list the full strain designation on the label. Here's the one we like best for overall gut health and bloat support if you're looking for a place to start.
- Feed your beneficial bacteria: The genera that increased in this trial thrive on dietary fiber (vegetables, legumes, and whole grains). Prebiotic fibers help good gut microbes flourish and are worth adding alongside any probiotic.
- Support the axis from both directions: The gut-brain connection is bidirectional, so consistent sleep hygiene and stress management complement what a probiotic can do.
As always, consult a healthcare provider before starting a new supplement.
The takeaway
Probiotics impact so much more than gut health. The right ones may even lift your mood and support better sleep. While these findings are preliminary, they add to growing evidence that targeting the gut microbiome may support emotional well-being as we age.
