Hydrogen-rich water has been shown to improve quality of life by enhancing mood, stress responsiveness, and autonomic regulation. The effects of hydrogen-rich jelly (HRJ) on autonomic responses during postural transition remain unclear. This double-blind, randomized, placebo-controlled crossover trial aimed to investigate the effects of HRJ on heart rate variability (HRV) indices in 50 healthy adults (21 males; mean age, 44.2 ± 11.3 years). HRJ (30–40 ppm, 10 g) was orally administered at 24 h, 1.5 h, and immediately before testing. The study protocol was approved by the Institutional Review Board of the Keio University School of Medicine (approval number: 20231194).HRV was continuously recorded during an orthostatic loading protocol consisting of four sequential 1-min phases: rest (seated baseline), stand-up (immediately after transitioning to standing), standing (sustained upright posture), and resitting (immediately after returning to sitting). We measured the coefficient of variation of the R–R interval (CVRR), low-frequency, high-frequency, and low-frequency-to-high-frequency (L/H) ratio components. Values for each posture were adjusted based on those at rest. Among the 48 participants with complete data under both conditions, HRJ intake resulted in a significantly lower CVRR during the stand-up phase (mean difference, −0.46; p = 0.047) and significantly lower L/H ratio during the resitting phase (mean difference, −1.51; p = 0.027). No significant differences were observed between the rest and standing phases. Our study suggests that HRJ intake modulates autonomic fluctuations during postural transitions.

This work was supported by Shinryo Co., Ltd. Dr. Katsumata received funding from this corporation. However, the company was not involved in the data analysis or manuscript writing. The other authors declare no conflicts of interest.

UMIN000053818

This work was supported by Shinryo Co., Ltd. However, this corporation was not involved in the study design, data collection, data analysis, or manuscript preparation.

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The study protocol was approved by the Institutional Review Board of the Keio University School of Medicine (approval number: 20231193) .

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All data from this study are presented in this manuscript or available from the corresponding author upon reasonable request.