Environmental Heat Stress Modulates Systemic Redox Homeostasis: A Longitudinal marker Analysis in Healthy Adults

Against the backdrop of more frequent extreme heat events driven by climate change and urbanization, clarifying the physiological effects of environmental heat exposure—particularly its impact on redox homeostasis in healthy populations—and identifying biomarkers for early heat-induced stress detection have become urgent public health priorities. This longitudinal study enrolled 330 healthy volunteers from four cities in Hubei Province (China), with fasting serum samples collected in March (mild temperatures) and August (high temperatures) to measure and analyze six redox markers: nitrite (NO₂⁻), nitrate (NO₃⁻), oxidized glutathione (GSSG), malondialdehyde (MDA), and total antioxidant capacity (assessed via FRAP and ABTS assays). High-temperature exposure significantly disrupted redox balance, characterized by decreased nitric oxide bioavailability, elevated lipid peroxidation, and enhanced serum antioxidant activity. Among the measured markers, MDA exhibited the most sensitive and consistent response to heat stress, with little interference from age or sex—supporting its potential as a reliable indicator for evaluating heat-induced oxidative damage. These insights may contribute to reducing health risks linked to extreme heat exposure.