Data published in Brain, Behavior, and Immunity indicated that daily consumption of encapsulated and non-encapsulated Lacticaseibacillus rhamnosus HN001 for six weeks produced distinct benefits on brain connectivity and grey matter volume in older adults, compared to placebo.
“This pioneering study compares the brain-related health effects of two distinct probiotic formulations of the same probiotic strain,” wrote researchers led by Dr. Julia Rode from Örebro University in Sweden.
“It is also the first to investigate the effects of probiotics on brain function in an elderly population using objective neuroimaging techniques, including magnetic resonance spectroscopy (MRS) to assess neurotransmitter levels.”
Gut-brain axis
The microbiota-gut-brain axis, the bidirectional interaction between the GI tract and the nervous system, is gaining increasing attention from researchers and the public, with a 2021 survey by FMCG Gurus revealing that 45% of consumers associated probiotics with cognitive health. The axis implicates the ability of specific strains to produce key neurotransmitters like GABA (gamma-aminobutyric acid), serotonin and dopamine, or their precursors.
The new study included 87 community-dwelling people between the ages of 60 and 80 who were randomly assigned to receive six billion CFUs per day of encapsulated or non-encapsulated L. rhamnosus HN001 or placebo for six weeks. The interventions were all provided by Cork-based AnaBio Technologies, and the micro-encapsulation technology is described as a “food-grade plant-based protein coating designed to protect the probiotic bacteria in the acidic environment of the stomach, leading to sustained release by gastrointestinal proteolytic enzymes.”
Functional Magnetic Resonance Imaging (fMRI) was used to assess potential impacts of the probiotic interventions on brain connectivity.
“Interestingly, there were distinct differences in connectivity comparing the encapsulated vs the non-encapsulated probiotic,” wrote Dr. Rode and her co-workers. “Overall, it seems that the encapsulated probiotic compared to placebo revealed altered connectivity between regions involved in visual perception and processing whereas the non-encapsulated probiotic compared to placebo affected the connectivity of regions involved in visual processing, language, memory as well as emotional regulation.”
When the researchers compared the results for the encapsulated versus non-encapsulated probiotics, they found that differences in brain connectivity between the groups for regions involved in visual processing, perception and memory.
Additional analysis showed that striatum levels of the neurotransmitter GABA (gamma-aminobutyric acid), circulating BDNF (brain-derived neurotrophic factor) or glutamate were not different between the groups. Alterations in neurotransmitters in the striatum region of the brain have previously been associated with aging, the researchers stated.
Cognitive function, measured using a battery of tests, revealed significant effects on processing speed, but no changes were recorded for measures of depression, perceived stress and sleep quality.
Release site vs dose
Commenting on the differences between the benefits observed in the probiotic groups, the researchers noted that given the interventions affected different brain circuitries, it appears unlikely that this is just a dose effect linked to more of the encapsulated probiotic reaching the appropriate site of action.
Encapsulation could lead to release of the probiotic later in the intestine, in this case the colon, which has a higher relative abundance of microbiota, and this may result in the larger production of neurotrophic factors by the microbiota.
“Given global population aging and the approximation that 15% of community-dwelling elderly suffer from mild cognitive impairment, strategies to promote healthy aging by maintaining brain health (i.e., cognitive function and mood balance) are warranted,” the researchers wrote.
“The findings from the present study suggest that supplementation with Lacticaseibacillus rhamnosus HN001 in apparently healthy older adults impacts resting state functional connectivity and grey matter volume and that encapsulation differentially affects these effects. As changes in resting state fMRI and grey matter volume have been shown to be associated with clinical diagnoses such as cognitive impairment and Alzheimer’s disease, or depression, the fact that probiotics can modulate these parameters highlights their potential in impacting disease pathology.”
Source: Brain, Behavior, and Immunity, 2025, Volume 130, 106113. doi: 10.1016/j.bbi.2025.106113. “Micro-encapsulation differentially impacts probiotic effects on brain structure and function in an elderly population – A randomised placebo-controlled trial”. Authors: J. Rode, et al.
