Data published in Frontiers in Nutrition indicated that a single dose of the postbiotic was associated with an increase in relaxation-associated brain alpha activity and improved parasympathetic nervous system activity, the body’s “rest and digest” mode that helps to stress, reduce heart rate and build resilience.
Additional data from an intestinal cell model revealed increases in serotonin secretion, which supported a mechanism implicating the gut-brain axis.
“Although further research is required to elucidate the underlying mechanisms, the concurrent modulation of cortical alpha activity, parasympathetic indices, and stress-related subjective measures suggests the relevance of gut-brain communication in these effects,” wrote the researchers.
“These findings suggest that heat-treated CP2305 could be a promising functional food ingredient that supports mental health, while highlighting the importance of extension in future studies.”
The microbiota-gut-brain axis
The ‘microbiota-gut-brain axis,’ a bidirectional interaction between the GI tract and the nervous system and implicates the ability of specific strains to produce key neurotransmitters like GABA, serotonin and dopamine.
The new study is said to be the first clinical study to examine the effects of postbiotics on alpha oscillatory activity in the brain.
“Even probiotics have not been found to have such capacity, except for Bifidobacterium longum (B. longum) 1714, making CP2305 an interesting strain for brain activity modulation,” wrote the Japan-based researchers. “While these two studies share the finding of post-stress alpha power enhancement, they differ in terms of bacterial viability, intervention duration, and stress modality.”
Study details
Twenty-eight health people aged between 20 and 44 were recruited for the double-blind, randomized, crossover, placebo-controlled study. The participants consumed either a single dose of the CP2305 postbiotic (10 billion cells) or placebo in two separate trial sessions, separated by at least three days (the washout period). Mental state was assessed during each session using the visual analog scale (VAS) and Profile of Mood States, 2nd edition (POMS2), and alpha activity was measured by EEG (electroencephalography).
The results showed that the postbiotic was associated with significant increases from baseline for alpha activity, compared with the placebo.
Significant improvements were also recorded for parasympathetic nervous system activity, according to measures of heart rate variability, in the heat-treated CP2305 intervention, compared to placebo.
CP2305 consumption was also associated with greater improvements in mental stress VAS and POMS2 tension–anxiety scores, compared with the placebo.
An additional in vitro cell study measuring serotonin (5-HT) secretion levels following heat-treated CP2305 administration showed higher extracellular 5-HT levels, indicative of a gut-brain mechanism.
“In addition to increasing sample size, future studies may help minimize avoidable data loss and potential bias by further standardizing data acquisition procedures and refining pre-assessment and screening procedures,” wrote the researchers.
“The elucidation of the mechanisms by which heat-treated CP2305 modulates brain oscillatory activity is an important next step. Additionally, a recent study showed that alpha power is linked to working memory. Ingredients that increase alpha power may have attractive benefits, such as improved working memory, and are therefore promising for future applications.”
Source: Frontiers in Nutrition, 2026, Volume 13, doi: 10.3389/fnut.2026.1796729. “Effects of heat-treated Lactobacillus gasseri CP2305 on brain oscillatory activity and mental stress in healthy adults: a double-blind, randomized, crossover, placebo-controlled trial”. Authors: R. Tanihiro, et al.
