Natural reduced water alters circulating immune-related protein profiles in healthy middle-aged adults: An exploratory proteomic analysis

Background Natural reduced water (NRW) possesses immunomodulatory properties; however, its underlying molecular mechanisms remain unclear. Aim We aim to investigate the effects of continuous NRW consumption on the plasma protein profiles of healthy middle-aged adults. Methods Forty-four middle-aged adults were randomly assigned to consume either NRW (Hita Tenryosui ® water) or tap water (1 L/day) for 6 months in a double-blind design. To evaluate group differences in protein expression, a linear mixed-effects model was applied. Paired t -tests were performed to evaluate within-group changes using a lenient threshold ( p < 0.1). Gene ontology enrichment analysis was performed for proteins that showed significant changes. Summary Six months of NRW consumption did not provide confirmatory evidence of statistically significant changes in plasma protein profiles compared with tap water in healthy middle-aged adults. Exploratory pathway analyses suggested possible differences in immune-related biological processes between the NRW and tap water groups. These findings should be interpreted as hypothesis-generating rather than definitive evidence of an intervention effect. Larger, adequately powered studies with prespecified proteomic endpoints are needed to validate these findings and determine their potential relevance to human health. The trial was registered with a clinical trials registry (registration number: UMIN000050462).