Creatine

Creatine is the most thoroughly studied supplement in sports science, and the evidence covers considerably more ground than gym performance. Here is what verified research shows, where Verhoeven's analysis adds interpretive color, and where genuine uncertainty remains.

Muscle and body composition

The scale going up after you start creatine is mostly water. A 2025 washout RCT by Desai et al. found no lean-body-mass advantage from creatine over 12 weeks of training once water was accounted for (p=0.71); the initial +0.51 kg gain (p=0.03) was fluid [1]. That finding, taken alone, would suggest creatine is a glorified sponge. The full picture is more nuanced. A 1999 biopsy study by Volek et al. measured actual muscle fiber cross-sectional area and found creatine produced significantly greater fiber growth than placebo across all fiber types (Type I: 35% vs 11%; Type IIA: 36% vs 15%; Type IIAB: 35% vs 6%) [2]. At the meta-analytic level, the Chilibeck 2017 meta-analysis found creatine combined with resistance training adds roughly 1.4 kg of real lean mass [3]. Taken together: the acute scale signal is water inflation, but modest real hypertrophy accumulates across months of training.

Cognition and the brain

Creatine's reputation as a brain booster rests largely on a single meta-analysis (Prokopidis et al. 2023, SMD 0.29, p=0.02). That result is formally contested. A published Letter by Eckert and Pascher 2023 raised the same methodological double-counting critique that analyst Nicolas Verhoeven had independently flagged [4]. The general memory claim is not supported by clean evidence.

What is supported, narrowly: creatine helped performance on an executive task under extreme sleep deprivation in the McMorris trial [5]. Separately, the Gordji-Nejad 2024 study supports a cognitive benefit specifically during sleep-deprivation stress [6]. Darren Candow, a researcher who has published extensively on creatine, frames the brain benefit as a stress-state and aging effect, not a general cognitive enhancer [7]. The blood-brain barrier is part of the problem: astrocytes lack the creatine transporter, making brain delivery harder than muscle delivery.

On dosing, Verhoeven's analysis suggests 5 g/day appears sufficient for muscle, while roughly 20 g/day may be needed to meaningfully raise brain creatine [8]. Verhoeven himself cautions that the evidence showing 20 g beats 5 g for the brain is "not strong" [8].

Depression

A 2026 RCT found that combining creatine with gut bacteria reduced depression scores (HAM-D) versus placebo in diagnosed MDD patients [9]. The proposed mechanism is specific: MDD patients show reduced creatine in blood and CSF, with evidence that gut microbiome composition (particularly Bifidobacterium species) gates intestinal creatine absorption via the Slc6a8 transporter [9]. A 2025 meta-analysis of 11 RCTs found a pooled SMD of -0.34 (95% CI -0.68, -0.00), translating to roughly 2.2 HAM-D points, below the 3.0-point minimal clinically important difference threshold; remission odds ratio was 3.60 across three trials, though heterogeneity was high (I²=71.3%) and GRADE certainty was rated low [10]. Verhoeven's analysis shows that every positive study enrolled clinically diagnosed, treatment-resistant MDD patients who were already on medication; null studies used Parkinson's, stroke, or healthy populations [11]. Creatine as a standalone mood intervention in healthy people is not supported.

Hair loss and kidneys

A 12-week double-blind RCT (Lak 2025, n=45) directly measured hair count and density and found no effect from creatine on any hair metric [12]. DHT/free-testosterone ratio shifted within the creatine group but identically in the placebo group; DHT itself did not rise [12]. The long-circulating DHT fear traces back to a 2009 biomarker study that never measured actual hair loss. People with androgenic alopecia genetics were not separately enrolled, so a small residual question remains for that group specifically, though no evidence points toward harm [13].

Creatine raises blood creatinine and lowers calculated eGFR, which looks alarming on a standard lab panel. A 2020 DB-RCT (Vilar Neto et al.) confirmed those changes but found kidney injury markers (KIM-1, MCP-1), urea, protein, and albumin all remained normal [14]. The eGFR drop is an artifact: more creatine in the body means more spontaneous conversion to creatinine, which inflates the molecule the eGFR formula uses as its proxy. Kidney function itself is intact. The ISSN position stand concurs, and safety data extend to 30 g/day over five years [15].

Cancer association

A large NHANES analysis (n=25,879, 2007-2018-11 years) found higher dietary creatine intake was inversely associated with cancer incidence: roughly 10.7 per 100 persons in the lowest intake quartile versus 9.2 in the highest [16]. Verhoeven's analysis explicitly labels this "encouraging but weak; no strong conclusions warranted" because dietary creatine tracks tightly with meat consumption, and total meat and energy intake were not controlled [17]. Confounding is substantial; causation is not established.

Where the evidence is contested

Muscle: water weight or real hypertrophy? Desai et al. 2025 found no lean-mass benefit on DEXA after correcting for water [1]. Volek et al. 1999 found real fiber-level hypertrophy by biopsy [2], and Chilibeck's meta-analysis found a small but real lean-mass gain across trials [3]. The studies are not necessarily contradictory: DEXA early in supplementation captures water inflation, masking modest structural gains that accumulate over longer periods. Both signals appear real.

Cognition: meaningful effect or methodological artifact? The Prokopidis 2023 meta-analysis reported a positive memory effect (SMD 0.29) [18]. Eckert and Pascher 2023 published a formal rebuttal identifying double-counting in the analysis [4]. The narrow sleep-deprivation benefit has cleaner support [5, 6], but general cognitive improvement in healthy, rested adults is not currently supported by uncontested evidence [19].

References

1. Desai et al. 2025, Nutrients 17(6):1081 — creatine washout LBM RCT · PubMed 40292479
2. Volek et al. 1999, Med Sci Sports Exerc — creatine + RT, muscle-fibre hypertrophy (biopsy) · PubMed 10449017
3. Chilibeck et al. 2017 — creatine+RT lean mass meta (older) · PubMed 29138605
4. Eckert & Pascher 2023 — Letter: double-counting in Prokopidis meta-analysis · PubMed 36644917
5. McMorris et al. 2006 — creatine, sleep deprivation & cognition · PubMed 17046034
6. Gordji-Nejad 2024, Sci Rep — creatine & sleep-dep cognition · PubMed 38418540
7. FoundMyFitness podcast — Rhonda Patrick × Darren Candow on creatine
8. Physionic — "Creatine Expert uncovers why 5 grams isn't Enough!" (video 06)
9. Lu et al. 2026 (Cell Metab) — creatine + gut microbiome + MDD; Slc6a8/Bifidobacterium mechanism; embedded RCT (creatine + B. adolescentis) · PubMed 41923613
10. Eckert et al. 2025 (Br J Nutr) — creatine depression meta-analysis; 11 RCTs, n=1,093; SMD −0.34 (borderline); ~2.2 HAM-D pts (below 3.0 MCID);… · PubMed 41189312
11. Physionic creatine video 01 — depression + gut microbiome
12. Lak et al. 2025 (JISSN) — creatine hair loss RCT (n=45, 12wk DB-RCT); null across all hair metrics; DHT/free-T ratio shift same in placebo · PubMed 40265319
13. Physionic creatine video 03 — hair loss RCT + DHT
14. Vilar Neto et al. 2020 (Toxicol Res) — creatine 3g/5g × 35d RCT; creatinine↑ + eGFR↓ confirmed as false positives; KIM-1/MCP-1/urea/protein all normal · PubMed 32670557
15. Kreider et al. 2017 — ISSN creatine position stand · PubMed 28615996
16. Jiang et al. 2025 (Front Nutr) — NHANES dietary creatine + cancer (n=25,879, 11yr); inverse association at highest quartile; heavy confounding… · PubMed 39867555
17. Physionic creatine video 04 — cancer risk (NHANES retrospective)
18. Prokopidis et al. 2023, Nutrition Reviews — creatine & memory meta-analysis (disputed)
19. 2024 systematic review — creatine cognition (skeptical) · PubMed 38582412