Reactive oxygen species (ROS), such as superoxide and hydrogen peroxide, are highly reactive molecules primarily produced as byproducts of cellular metabolism by mitochondria and NADPH oxidases. ROS play a paradoxical "double-edged sword" role in human biology, acting as crucial regulators of both health and disease.

The Dual Role of ROS At low to moderate concentrations, ROS function as vital signaling molecules that maintain cellular homeostasis, a state termed "oxidative eustress". They regulate essential physiological processes, including cell proliferation, cellular differentiation, immune responses, and autophagy. This adaptive, protective cellular response to mild oxidative exposure is known as hormesis.

However, when ROS production overwhelms the body's antioxidant defense systems, it causes "oxidative distress" or oxidative s ...