Effect of Single Oral Coingestion of GABA and Malic Acid on Postprandial GLP-1, Glucose, and Insulin Responses in Healthy Volunteers: A Randomized, Double-Blind, Placebo-Controlled, Crossover Study.

SCOPE: This study examines whether coingestion of γ-aminobutyric acid (GABA) and malic acid (MA) before meals enhances glucagon-like peptide-1 (GLP-1) secretion, and which affects subsequent insulin and glycemic responses in humans. METHODS AND RESULTS: Initially, a murine enteroendocrine STC-1 cell line is used to verify coadministration of GABA and MA synergistically induces GLP-1 secretion. Next, 22 healthy adults are given water (50 mL) containing 400 mg GABA and 400 mg MA (Test), or only 400 mg citric acid (CA) (Placebo) 20 min before meal tolerance test (MTT). Interval blood samples are taken postprandially over 180 min to determine GLP-1, insulin, and glucose responses. By comparison to preload of Placebo, preload of Test significantly increases plasma GLP-1 (total/active) levels (incremental area under the curve by 1.2- and 1.6-fold), respectively. However, there are no significant differences in postprandial blood glucose and insulin. CONCLUSION: Coingestion of GABA and MA before meals enhances postprandial GLP-1 secretion. Future studies should explore optimal dosage regimens to find the efficacy of the mixture on insulin and glycemic response.

Effect of cooked white rice with high ß-glucan barley on appetite and energy intake in healthy Japanese subjects: a randomized controlled trial.

White rice is a dominant grain-based food in Japan, but excess intake of polished rice may cause obesity. Barley is a grain-based food, similar to white rice, but it has the potential to control appetite and reduce energy intake. We investigated the effect of cooked white rice with high ß-glucan barley on appetite and energy intake. The study was conducted as a randomized crossover design with twenty-one healthy Japanese women [mean ± standard deviation body mass index (BMI) 23.3 ± 0.7 kg/m(2)]. Subjects consumed a breakfast of cooked white rice with high ß-glucan barley (BAR) or white rice (WR), followed by an ad libitum lunch and dinner. Energy intake was measured at the lunch and the dinner using plate waste. Subjects' perception scores on hunger, fullness, satiety, and prospective food consumption were assessed using a visual analogue scale (VAS) before and after the breakfast, lunch and dinner. BAR significantly reduced the VAS scores of hunger and prospective food consumption, and increased fullness before lunch compared to WR (P = 0.032, 0.019 and 0.038, respectively). Energy intake at lunch and the cumulative energy intake (lunch + dinner) subsequent to BAR consumption were significantly lower than WR (P = 0.035 and 0.021, respectively). BAR was able to modulate appetite and reduce energy intake. The combination of white rice with high ß-glucan barley could play a beneficial role in preventing and treating obesity and other obesity-related metabolic diseases.