Acute Effects of Hom Pathum and Tubtim Chumphae Rice Jellies on Glycemic Response, Endurance Performance, and Oxidative Stress in Healthy Adults: A Randomized Crossover Study

Thai rice varieties, including Hom Pathum (Pathumthani fragrant rice) and Tubtim Chumphae rice, contain bioactive compounds with potential antioxidant properties. In this study, their acute effects on glycemic response, cardiac autonomic function, endurance performance, and oxidative stress were investigated in healthy adults. In a randomized crossover design, two independent cohorts of healthy adults were enrolled. A total of 50 participants completed two separate experiments (n = 25 per experiment), in which they consumed 140 g of control jelly, Hom Pathum rice jelly, and Tubtim Chumphae rice jelly in a randomized order on separate occasions. In Experiment 1, blood glucose (BG) was measured at baseline and every 30 min for 120 min, while insulin concentrations were assessed at baseline and after 120 min. In Experiment 2, participants performed treadmill exercise at 60% VO2peak to volitional exhaustion, and exercise-induced oxidative stress was evaluated following exercise. Postprandial BG responses differed significantly among interventions. At 30 min, BG concentrations were lower following Hom Pathum and Tubtim Chumphae rice jellies compared with the control jelly (p < 0.001 and p = 0.002, respectively), and these reductions were maintained between 60 and 120 min, with Tubtim Chumphae rice generally demonstrating greater glycemic attenuation (p < 0.05). The BG area under the curve was significantly lower following both rice jellies than following the control jelly (p ≤ 0.005). No significant differences were observed in insulin concentrations, HOMA indices, heart rate variability, or blood pressure among interventions. Both rice jellies improved endurance performance compared with the control condition (p < 0.05), whereas post-exercise malondialdehyde concentrations were significantly reduced only following Tubtim Chumphae rice consumption (p = 0.049). These findings suggest that acute consumption of Thai rice-based jellies, particularly Tubtim Chumphae rice jelly, may attenuate postprandial glycemic responses and enhance endurance performance, with Tubtim Chumphae rice additionally demonstrating potential to reduce exercise-induced oxidative stress. However, these findings reflect short-term physiological responses in healthy adults and should be interpreted cautiously pending further mechanistic and long-term investigations.