Optimum Nutrition Micronized Creatine is Industry-leading creatine monohydrate with consistent quality, micronization, and Informed Sport testing. Glanbia positions this product at approximately $15/month at the standard 5 g/day dose. This review covers what's in the bottle, how it compares to peer brands, and whether it justifies its price.

Creatine is a naturally occurring compound synthesized in the liver, kidneys, and pancreas from arginine, glycine, and methionine. About 95% of body creatine resides in skeletal muscle, with the remainder in brain, heart, and other high-energy tissues. Dietary creatine comes primarily from red meat and fish (~1 g/day in omnivores; near-zero in vegans).

Inside cells, creatine is phosphorylated to phosphocreatine (PCr), which serves as a rapid ATP-regeneration system. During short, high-intensity efforts (1–10 seconds), the ATP–PCr system is the dominant energy supplier. Creatine supplementation increases muscle PCr stores by 10–40%, improving repeat-effort performance, strength, and lean mass gains over weeks of consistent training.

Beyond muscle, creatine has well-documented brain effects. The brain uses creatine for cognitive demands and during stress (sleep deprivation, hypoxia, mental fatigue). Vegetarians, vegans, women, and older adults have consistently shown the largest cognitive benefits — likely because their baseline brain creatine is lower. Therapeutic uses are emerging in depression, ADHD, traumatic brain injury, and Parkinson's disease as adjunctive support.

Creatine monohydrate is the gold standard form — over 1,000 published studies, ~99% absorption, and the lowest cost-per-effective-dose of any major supplement. The patented Creapure form (manufactured in Germany by AlzChem) is the most-tested creatine raw material globally and is used by premium brands. Other forms (HCl, buffered Kre-Alkalyn, ethyl ester, magnesium chelate, liquid, gummies) marketed as "more bioavailable" or "less bloating" do not have evidence supporting superiority over monohydrate; they typically cost 2–5× more for equivalent or inferior effect.