Prebiotics May Boost Brain Health, Study Suggests

Researchers are exploring how gut health may influence brain function. A recent study discovered that certain dietary additions could potentially elevate brain GABA levels, which play a role in calming the mind. This work could open avenues for treating neurological disorders.

Gut-Brain Connection Explored

GABA, or gamma-aminobutyric acid, is a crucial amino acid that acts as an inhibitory neurotransmitter within the brain. Low levels are linked to conditions like depression and epilepsy. Scientists have been examining the link between gut health, mental well-being, and how specific foods might affect the brain.

In trials conducted on mice, researchers investigated whether brain GABA levels could be enhanced through dietary changes. The goal was to modulate gut bacteria to bypass the blood-brain barrier. The results were published in npj Science of Food in April 2025.

While the gut-brain connection is not novel, it is gaining attention. The study aimed to clarify the direct communication between the two systems: can increased gut-derived GABA directly lead to increased brain GABA levels?

Researchers found a direct link among gut GABA, brain GABA, and the gut microbiota during mouse trials. There are no conclusive results, however, as to whether gut microbiota-derived GABA can cross the blood-brain barrier to increase brain GABA. Further studies point to other possible pathways to increase brain GABA, such as through the Vagus nerve or hormonal pathways.

“Our study suggests that prebiotics have the ability to prevent or treat those brain diseases by increasing brain GABA levels via promoting gut GABA production through modulating gut microbiota.”

—Thunatchaporn Kumrungsee, Study Corresponding Author, Associate Professor at Hiroshima University’s Graduate School of Integrated Sciences for Life

The research team discovered that fructo-oligosaccharides (FOS) and enzymes derived from Aspergillus, like lipase and protease, elevated brain GABA levels in mice. FOS showed a significant increase in brain GABA in both the cortex and hippocampus, areas where GABA reduces excitability and promotes calmness. Additionally, FOS and enzyme supplementation increased homocarnosine levels in the hippocampus.

Food factors such as prebiotics and fungi-derived enzymes with prebiotic-liked effects have an ability to increase brain GABA and homocarnosine, a GABA-containing brain-specific peptide, which can possibly in turn enhance brain health through gut microbiota modulation, said Kumrungsee.

Homocarnosine has links to similar brain diseases. According to a prior study by Kumrungsee, homocarnosine-deficient mice showed depression-like behaviors and hyperactivity.

Despite a lack of proof of direct gut microbiota-derived GABA increases in the brain, the study indicates that prebiotic consumption may boost brain GABA levels. Further research is needed to understand the exact mechanisms by which the gut influences the brain. Ultimately, researchers hope to determine if the prebiotic treatments from this study can treat GABA-related conditions, such as epilepsy and depression.

According to the National Institute of Mental Health, in 2022, an estimated 28.3 million adults in the United States had a major depressive episode Source.

Study Contributors

Researchers contributing to this work included Jason D. Braga, Norihisa Kato, Noriyuki Yanaka, and Thanutchaporn Kumrungsee from the Program of Food and AgriLife Science at Hiroshima University. Also contributing were Jason D. Braga from the Institute of Food Science and Technology at Cavite State University, Yongshou Yang from the School of Life Sciences at Anhui University, and Kyoichi Nishio, Masasumi Okada, Manabu Kuroda, and Shotaro Yamaguchi from Amano Enzyme Inc.

This research was funded by the Japanese Society of Functional Fermented Foods and Enzyme Supplements, the Danone Institute of Japan Foundation research grant, the Japanese Ministry of Education, Culture, Sports, Science and Technology, and Amano Enzyme Inc.