According to a meta-research review published in the journal Nutrients and reported by NutraIngredients, only 0.9% of 343 randomized controlled trials on oral creatine supplementation directly discussed bioavailability — a gap that researchers say leaves marketing claims about "enhanced" creatine formulations scientifically unsupported.
The analysis, conducted by authors from the University of Split in Croatia and Jagiellonian University Medical College in Poland, drew from 357 reports in MEDLINE and Embase covering trials published between 1994 and 2023. Creatine monohydrate remained the dominant intervention at 275 trials (80.2%), yet 53 reports (15.5%) failed to specify the chemical form used at all.
The Reporting Deficit
Bioavailability was mentioned in only 38 reports (11.1%). Four trials (1.2%) reported specific measures intended to enhance it. Five trials (1.5%) compared more than one creatine formulation; only three addressed bioavailability, and those comparisons were frequently compromised by non-equimolar dosing — a methodological artifact that makes direct efficacy claims between formulations untenable.
The problem runs deeper at the formulation level: solubility-enhanced variants such as creatine citrate and creatine pyruvate deliver creatine alongside another nutrient with independent ergogenic properties, yet control groups rarely account for the non-creatine component. PEGylation strategies — attaching creatine to polyethylene glycol to extend half-life and solubility — were flagged as promising but "often underrepresented in RCTs."
The Cognitive Blind Spot
Of the 343 RCTs reviewed, only two targeted brain creatine concentrations rather than muscle uptake. The authors identify this as the most understudied research area in the creatine literature — a notable omission given the explicit interest in creatine's role in supporting cognitive health and the absence of pharmacokinetic bridging between peripheral and central measures.
The review's operational recommendations are explicit: future trials must report the exact chemical formulation used, incorporate pharmacokinetic endpoints such as circulatory creatine concentration, and apply non-equimolar dosing when evaluating alternative products. Without these changes, "enhanced bioavailability" remains a marketing distinction rather than a clinical one.
What This Changes for Cognitive Performance
For practitioners and self-experimenters tracking measurable cognitive outcomes, the evidence hierarchy is now clearer. Creatine monohydrate retains the trial base. Any move to a novel formulation should require independent pharmacokinetic data — serum or plasma creatine curves, time-to-peak, area-under-the-curve — before it earns a place in a stack. Vendor brochures do not count as endpoints.
The same evidentiary standard is now being applied across the broader cognitive enhancement landscape, from nootropic formulations to AI-driven platforms reshaping how students engage with learning. When the mechanism cannot be measured against the claim, the claim remains provisional.