From molecular mechanisms to translational applications: a parallel assessment of green and black tea modulation of oxidative stress.

Oxidative stress, driven by an imbalance between reactive oxygen species (ROS) and antioxidant defenses, is a key contributor to aging and chronic diseases such as cancer, cardiovascular disorders, and neurodegenerative conditions. Green and black tea contain polyphenolic compounds that exhibit potent antioxidant and anti-inflammatory activities. This review parallelly compares the different molecular mechanisms by which black and green tea regulate oxidative stress, including direct ROS scavenging, activation of endogenous antioxidant pathways (e.g., Nrf2/ARE), inhibition of pro-oxidant enzymes and inflammatory signaling, metal ion chelation, mitochondrial protection, and modulation of autophagy and metabolic reprogramming. Comparative analysis highlights the unique roles of green and black tea in oxidative stress regulation, supported in vitro, in vivo, and clinical evidence. This review underscores the promise of tea polyphenols as natural antioxidants for preventing and managing oxidative stress-related diseases, while emphasizing the need for precision dosing and targeted interventions to optimize their clinical utility.