Memory or mood? Why probiotic capsules and powders may affect the brain differently

Intervention effects on resting state functional connectivity superimposed on a standard brain template in MNI space, visualized in the coronal, sagittal and axial plane. Credit: Brain, Behavior, and Immunity (2025). DOI: 10.1016/j.bbi.2025.106113

How you take probiotics can affect their impact on the brain. A study from Örebro University points to new possibilities for personalized approaches, depending on whether the primary aim is, for example, to improve memory or reduce depression. The research is published in the journal Brain, Behavior, and Immunity.

“Personally, I didn’t think it would make much difference how we consume probiotics. Our study shows that memory and concentration can change if the probiotic powder is encapsulated, whereas powder that is not encapsulated has a greater effect on mental health, such as anxiety, depression and similar conditions,” says Julia Rode, researcher in biomedicine at Örebro University, whose particular focus is on the connection between the gut and the brain.

Probiotics are good bacteria that contribute to brain health and are usually consumed through food or functional drinks. How the bacteria are prepared plays a major role in storage and shelf life, and they also behave differently in the intestinal tract, which affects the brain. Encapsulated powder can be compared to baking powder, which also comes in different forms. The coating allows it to remain active longer and not react immediately, for example, with dough. In the same way, encapsulated powder means that a larger proportion of the good bacteria reach further into the gut.

“We saw that the form had different effects on the brain. It’s not that one form is better than the other—it depends entirely on what the individual needs to strengthen. Different preparation methods are useful in different situations,” explains Rode.

An increasing number of studies show that the gut microbiota affects the brain and, in turn, how we age. In the study conducted at Örebro University, participants were given probiotics in different forms, and the effects on the brain were examined using magnetic resonance imaging (MRI), brain function tests, and questionnaires.

The study is the first to be conducted in healthy older adults and to compare different methods of preparing probiotics. There are a small number of previous studies that demonstrate a link between the gut and the brain using magnetic resonance imaging (MRI or “brain scanner”).

“Probiotics are beneficial for brain function, and with data from this study, we can hopefully contribute further to our understanding of how probiotics can be consumed, for example, to cope with stressful periods,” says Rode.

About the study

A total of 87 people aged 60–80 participated in the study. They were given either microencapsulated or non-encapsulated probiotic bacteria from the same strain and at the same dose. A control group received a placebo with no effect to compare results.

The results showed clear differences in the brain’s functional connections, depending on how the probiotics were taken. The results reinforce the connection between the gut and the brain—the so-called gut-brain axis—and how it can contribute to healthier aging. The form of the powder had different effects on brain function:

1. Encapsulated powder affected cognition, including memory, focus, attention and orientation.
2. Non-encapsulated powder affected mental health, which may influence low mood, anxiety and depression.

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