Efficacy and Safety of Low-Dose Gamma-Aminobutyric Acid From Unpolished Rice Germ as a Health Functional Food for Promoting Sleep: A Randomized, Double-Blind, Placebo-Controlled Trial.

Gamma-aminobutyric acid (GABA)-enriched fermented foods have the potential to ame-liorate insomnia because of their inhibitory action on the central nervous system. 1 As functional foods, they are safe for oral intake, easily accessible, and can relieve anxiety and elevate mood. 2 We previously demonstrated that 4 weeks of natural GABA extracts (300 mg daily) can improve both subjective sleep quality and objective sleep efficacy. 3 Natural-GABA treatment reduced sleep latency and improved sleep questionnaire scores. However, two out of forty patients complained of abdominal discomfort, and one patient complained of headache after receiving the natural-GABA treatment. Also, since insomnia often requires long-term ther-apy, the adverse effects may have been underestimated. Accordingly, in the present study we explored whether low-dose natural GABA (75 mg) is as effective in improving sleep quality and sleep efficacy as is high-dose natural GABA (300 mg), and without adverse events. This study performed a double-blind, randomized, placebo-controlled trial of low-dose natural GABA (75 mg) in patients with insomnia. The study design was equivalent to that of our previous study. 3 The primary outcome was the changes in overnight polysomnogra-phy (PSG) sleep latency and sleep efficacy between baseline and after 4 weeks in the GABA-treatment population. The secondary endpoints were changes in other PSG parameters and sleep questionnaire scores between baseline and 4 weeks. Differences between the study groups at baseline were assessed using either the chi-square or Fisher’s exact test for categorical data, and the t -test for continuous data. Changes from baseline to 4 weeks after treatment in each treatment group were determined using the Wilcoxon signed-rank test.