Abstract

Oxidative stress, resulting from an imbalance between the production of reactive oxygen and nitrogen species 
(ROS/RNS) and the capacity of endogenous antioxidant defenses, is a central driver of cellular dysfunction, 
immune dysregulation, and chronic disease. Phytochemicals, a diverse group of bioactive compounds found in 
fruits, vegetables, herbs, and spices, have emerged as potent regulators of oxidative stress. These compounds not 
only directly scavenge reactive species but also modulate key signaling networks involved in antioxidant defense, 
inflammation, apoptosis, and immune response. Through activation of redox-sensitive transcription factors such as 
nuclear factor erythroid 2–related factor 2 (Nrf2) and inhibition of pro-oxidant enzymes, phytochemicals enhance 
cellular antioxidative capacity and support immune cell function. This review synthesizes current knowledge on 
the molecular mechanisms by which phytochemicals regulate oxidative stress and explores the implications for 
immune regulation and cellular defense. We highlight evidence linking dietary phytochemicals to improved 
immune homeostasis and disease resistance, discuss their effects on chronic inflammation and cellular signaling 
pathways, and examine challenges in clinical translation, including bioavailability and individualized responses. 
Understanding how phytochemicals modulate oxidative stress and immunity provides valuable insights into their 
potential as therapeutic agents and nutritional interventions in health maintenance and disease prevention.