The Effect of Oral GABA on the Nervous System: Potential for Therapeutic Intervention

Gamma-aminobutyric acid (GABA), the primary inhibitory neurotransmitter in the central nervous system (CNS), plays a pivotal role in maintaining the delicate balance between inhibitory and excitatory neurotransmission. Dysregulation of the excitatory/inhibitory balance is implicated in various neurological and psychiatric disorders, emphasizing the critical role of GABA in disease-free brain function. The review examines the intricate interplay between the gut–brain axis and CNS function. The potential impact of dietary GABA on the brain, either by traversing the blood–brain barrier (BBB) or indirectly through the gut–brain axis, is explored. While traditional beliefs questioned GABA’s ability to cross the BBB, recent research challenges this notion, proposing specific transporter systems facilitating GABA passage. Animal studies provide some evidence that small amounts of GABA can cross the BBB but there is a lack of human data to support the role of transporter-mediated GABA entry into the brain. This review also explores GABA-containing food supplements, investigating their impact on brain activity and functions. The potential benefits of GABA supplementation on pain management and sleep quality are highlighted, supported by alterations in electroencephalography (EEG) brain responses following oral GABA intake. The comprehensive overview encompasses GABA’s sources in the diet, including brown rice, soy, adzuki beans, and fermented foods. GABA’s presence in various foods and supplements, its association with gut microbiota, and its potential as a therapeutic strategy for neurological disorders are thoroughly examined. The articles were retrieved through a systematic review of the databases: OVID, SCOPUS, and PubMed (keywords “GABA”, “oral GABA“, “sleep”, “cognition”, “neurodegenerative”, “blood-brain barrier”, “gut microbiota”, “supplements” and “therapeutic”, and by searching reference sections from identified studies and review articles). This review presents the relevant literature available on the topic and discusses the mechanisms, effects, and hypotheses that suggest oral GABA benefits range from neuroprotection to blood pressure control. The literature suggests that oral intake of GABA affects the brain illustrated by changes in EEG scans and cognitive performance, with evidence showing that GABA can have beneficial effects for multiple age groups and conditions. The potential clinical and research implications of utilizing GABA supplementation are vast, spanning a spectrum of diseases ranging from neurodegeneration to blood pressure regulation. Importantly, recommendations for the use of oral GABA should consider the dosage, formulation, and duration of treatment as well as potential side effects. Effects of GABA need to be more thoroughly investigated in robust clinical trials to validate efficacy to progress the development of alternative treatments for a variety of disorders.