In a randomized, double-blind study of post-COVID adults, a single 50 mg dose of a plant-based supplement reduced mitochondrial, iNOS, and NOX2-driven oxidative stress more broadly than 1000 mg vitamin C. It also increased bioavailable nitric oxide, unlike vitamin C. Both reduced TNFα-induced ROS. Results suggest stronger antioxidant and immune-support effects with the plant-based blend during recovery.