RAW Nutrition Peak O2 is a non-stimulant performance supplement designed to support oxygen utilization, endurance, and work capacity rather than short-lived energy spikes. Built around the clinically studied PeakO2® mushroom blend, it targets fatigue at its source by helping athletes sustain output, delay lactate buildup, and perform longer at higher workloads. This in-depth review breaks down the science, supplement facts, real-world training benefits, and who Peak O2 is best for, from bodybuilders and hybrid athletes to endurance-focused trainees. If you train hard, value consistency, and want better performance without relying on stimulants, Peak O2 offers a smart, understated edge.