Glutathione, the body’s most important intracellular antioxidant, plays a far-reaching role in the immune system that goes beyond simply neutralizing oxidative stress. As a crucial player in nutritional immunity, glutathione helps regulate nutrient competition between the host and pathogens, ensuring that pathogens are deprived of essential nutrients, like cysteine, that are critical for their survival. Through its involvement in redox signaling, cytokine production, and immune cell activation, glutathione contributes to immune resilience, particularly under nutrient-limited conditions.