Seasonal summer stress affects systemic redox homeostasis: a longitudinal marker analysis in healthy adults

As global climate change and urbanization accelerate, summer heat waves are becoming more frequent and intense, posing an increasing threat to human health. However, previous studies have predominantly focused on the impact of summer high temperatures on people with pre-existing diseases, with few reports investigating their effects on healthy individuals. Redox balance is a core foundation of human health and is closely linked to changes in ambient temperature.

The present study enrolled 330 healthy volunteers from four cities in Hubei Province, China. Fasting serum samples were collected during spring (mild temperatures) and summer (high temperatures), and the levels of six redox markers were measured and analyzed: nitrite (NO₂ ^-), nitrate (NO₃ ^-), oxidized glutathione (GSSG), malondialdehyde (MDA), and total antioxidant capacity.

The results revealed that under natural summer stress, systemic redox homeostasis in healthy individuals is significantly perturbed, characterized by reduced nitric oxide bioavailability, elevated lipid peroxidation, and enhanced serum antioxidant activity. Notably, MDA was the most sensitive biomarker in response to natural summer stress, with minimal interference from age or sex, suggesting its potential as a reliable biomarker for oxidative damage induced by natural summer stress in healthy individuals.

Furthermore, significant methodological biases may arise if the seasonal variations in serum MDA levels are not taken into account when researching in this area. These findings provide a novel direction for investigating the impacts of high summer temperatures on health and may lay the foundation for guiding public health practices.