Hydrogen-rich water antioxidant effect on Nrf2 and lung in smoke-exposed rats: a randomized controlled trial

BACKGROUND: Cigarette smoke contains harmful free radicals and ROS, leading to proinflammatory cytokine activation and lung damage. This study aimed to determine the antioxidant effect of hydrogen-rich water (HRW) on the lungs of mice exposed to cigarette smoke for 28 days.METHODS: This study used 20 rats, divided into four groups (N.=5): control 1 ([CI] distilled water + normal air), control 2 ([CII] distilled water + cigarette smoke), treatment group 1 ([TGI]; HRW 5 mL/day + cigarette smoke), and treatment group 2 ([TGII]; HRW 5 mL twice/day + cigarette smoke). HRW/distilled water was administered orally 30 minutes before smoke exposure. Cigarette smoke exposure was once daily for 28 days using 5 cigarettes. Afterward, the right lung was examined for nuclear factor-erythroid 2-related factor 2 (Nrf2) levels via ELISA, and the left lung was used for histopathological examination.RESULTS: The results showed that administration of HRW could increase Nrf2 levels induced by exposure to cigarette smoke - there was a statistically significant difference (P<0.05). Histopathological examination showed that administering HRW 5 mL once per day could reduce the degree of lung inflammation caused by exposure to cigarette smoke in the TGI group (P=0.119), but it was not significantly different. Significant results were seen in the TGII group (P=0.041) who were given HRW 5 mL twice a day.CONCLUSIONS: HRW has an antioxidant effect on lungs exposed to cigarette smoke and is related to the total volume of HRW consumed per day.