The fastest backup battery your muscles and brain have. It's the best-supported supplement on this site.
Mechanisms, studies and evidence grades for each claim above.
Phosphocreatine donates a phosphate group to ADP via creatine kinase, regenerating ATP faster than glycolysis or oxidative phosphorylation can. That's why it matters most for short, high-intensity efforts (roughly under 3 minutes) rather than endurance output. It also shuttles high-energy phosphate from mitochondria to where ATP is used in the cell. The body makes about 1 g/day from glycine, arginine and methionine (via SAMe, which makes creatine synthesis a large consumer of methyl groups; see Methionine). Meat and fish supply roughly another 1 g/day. Muscle holds ~95% of the body's creatine, but the brain, heart, retina and testes also rely on it. Supplementing raises muscle stores by roughly 20–40%, most in people starting low.
This is one of the most replicated findings in sports nutrition. A meta-analysis of 53 RCTs (1,138 participants) found creatine improved upper-body strength (bench and chest press) regardless of age, sex, training status or dosing protocol.1 Companion analyses by the same group show the same for lower-body strength. The effect is moderate per session, but it adds up over months because each workout is a bit more productive. (Strong)
↑ back to summaryA meta-analysis of 22 RCTs in 721 older adults (mean age 57–70) doing resistance training found creatine added 1.37 kg of lean mass over placebo, along with greater chest-press and leg-press strength.2 Losing muscle is one of the strongest predictors of frailty and death in old age. Creatine plus lifting is one of the few interventions that reliably pushes the other way. (Strong — for creatine with training; creatine alone does little)
↑ back to summaryThe brain uses about 20% of the body's energy and runs its own creatine–phosphocreatine buffer. Evidence that supplementing helps:
The pattern is clear: creatine helps the brain most when its energy supply is under strain. (Moderate — small RCTs, consistent in the groups that are low or stressed)
↑ back to summaryIn 52 women with major depression starting escitalopram, adding 5 g/day creatine produced significantly greater improvement on the Hamilton Depression scale than placebo, starting as early as week 2 and holding through week 8.6 Brain-imaging follow-up by the same group linked this to changes in frontal energy metabolism. The trial involved women only, and it hasn't been replicated at scale. (Moderate — one well-designed RCT)
↑ back to summaryHair: in one study of 20 college rugby players, 3 weeks of creatine raised dihydrotestosterone (DHT) by 56% during loading and kept it 40% above baseline during maintenance. Testosterone didn't change.8 No study has shown actual hair loss, and this single result hasn't been replicated, but men prone to male-pattern baldness may reasonably want to watch for it. Water weight: 1–2 kg is typical in the first weeks. The water is inside muscle cells, not under the skin. Stomach: GI upset mainly occurs with large single doses.
↑ back to summaryCreatine's energy buffer isn't just for muscle and brain. Any cell under heavy, fluctuating energy demand can use it, and that includes both the immune cells that attack a tumor and the tumor cells themselves. The mouse literature has found both effects:
The only human data is one cross-sectional NHANES analysis. In 25,879 US adults, each standard-deviation increase in dietary creatine intake was associated with 5% lower odds of having ever had cancer (OR 0.95, 95% CI 0.91–0.99).13 That's a weak association, and it can't show cause and effect. Dietary creatine is really a marker of meat and fish intake, and it measures cancer at the same moment it measures diet, so people already diagnosed may have changed how they eat. (Early — no human trial has tested creatine for cancer in either direction)
Bottom line: creatine may help the immune system attack a primary tumor and may also help cancer cells survive once they spread. These mouse findings don't say which effect wins in people. For healthy people this is no reason to start or stop creatine, and the decades of human safety data show no cancer signal. For someone with active cancer, especially colorectal or breast cancer, or on immunotherapy, it's a question for the oncologist. The same "energy and antioxidant support don't pick sides" logic is on the NAC page, and it fits the Cancer paper's metabolic framing.
↑ back to summarySkin fibroblasts use the creatine kinase system too, and energy supply declines in aging skin. In cultured human fibroblasts, creatine increased collagen gene expression and procollagen production.14,15 In the clinical part of the study, 43 men applied a face cream containing creatine, guarana extract and glycerol for 6 weeks. Jowl sagging, crow's feet, under-eye wrinkles and eye bags all improved compared with their own baseline.14 A companion study found a folic acid plus creatine cream improved firmness in mature skin.15
The limits are significant. Both papers come out of Beiersdorf's R&D department in Hamburg, and Beiersdorf sells creatine creams under the Nivea brand. There was no placebo-cream control, so glycerol (a humectant that plumps skin on its own), guarana, the moisturizing base and the placebo effect can't be separated from creatine. And it was a cream: nothing here shows that oral creatine reaches the skin or changes it. (Early — in-vitro plus one uncontrolled, industry-run cream study; no evidence for oral creatine)
↑ back to summaryTwo posts from 28 September 2026: Dalton (@Outdoctrination, "Biomolecular Engineer", sells paid consultations) on skin and cancer risk, and Daniel Tawfik (@dantawfik, molecular biologist from UCLA, founder of gethealthspan.com) summarizing the UCLA dendritic-cell paper. Each claim was checked against the primary paper.
| Claim | What the literature shows | Does it hold up? |
|---|---|---|
| "People using a creatine face product showed improvements in multiple wrinkles / sagging metrics" (Dalton) | True as reported. 43 men, 6 weeks, a cream with creatine, guarana and glycerol, measured against their own baseline with no placebo cream. The study came from Beiersdorf (Nivea) R&D.14 | Holds for the cream, weakly. It says nothing about the oral powder most readers take. A reply to Dalton asked whether mixing monohydrate into a cream would work; nobody has tested that either. |
| "Creatine was shown to stimulate collagen production in skin cells" (Dalton) | Yes, in cultured fibroblasts and collagen gels.14,15 | In a dish. A plausible mechanism, but not evidence of anything in a living person's skin. |
| "Creatine is strongly linked to a decreased risk of getting cancer" (Dalton's quoted thread) | NHANES cross-sectional study: 5% lower odds per SD of dietary creatine, a confidence interval that nearly touches 1 (0.91–0.99), and no supplement data.13 | Overstated. It's a weak link, not a strong one; it measures meat intake, not supplements; and it can't separate cause from reverse causation. |
| "Pretty much any nutrient can 'stimulate cancer cells'" (Dalton, answering a reply) | Creatine has specific mouse evidence of promoting metastasis through its own pathways (GATM, SLC6A8, creatine kinase B).11,12 | A deflection. The replier was pointing at a real, creatine-specific literature that neither post mentions. |
| Creatine "powers the immune cells that direct your body's cancer-fighting response" (Tawfik) | Accurately describes the UCLA findings: CrT knockout, the ATP mechanism, the human-cell experiments, and B16 melanoma growth slowed.9 | Holds in mice. A fair headline for the biology, and Tawfik lists the limits (one tumor model, young mice, transplanted tumors). |
| "Mice received either regular drinking water or water supplemented with creatine" (Tawfik) | The paper's methods say daily intraperitoneal injection of 10.5 mg creatine.9 | Wrong. That matters for translation. Injection skips the gut, so "oral creatine did this" is not what was shown. |
| "When the researchers depleted dendritic cells, creatine supplementation no longer suppressed tumor growth" (Tawfik) | I found no dendritic-cell depletion experiment in the paper's text or methods. The dendritic-cell link rests on the knockout and on correlations in tumor tissue. | Not in the paper. This is the post's strongest causal claim, and it appears to have been invented. The whole summary reads like an AI-generated writeup. |
| Doses "within the range commonly used by athletes (3–5 g/day)" (Tawfik) | 10.5 mg/day in a ~20 g mouse is ~500 mg/kg. Scaled by body-surface area, that's roughly 40 mg/kg, or about 3 g/day for a 70 kg human. | Roughly right, but for injected creatine in animals whose diet has none, which isn't the same as oral creatine on top of a meat-containing diet. |
| "Previous studies... showed creatine enhances CD8 T cell function" (Tawfik) | Correct: Di Biase et al. 2019, from the same UCLA lab.10 | Holds, though it's the same group, not independent replication. The metastasis papers go unmentioned. |
Verdict: neither post changes how to use creatine. It remains the best-supported supplement on this site for muscle, aging and brain, at 3–5 g/day. The skin claim applies only to a cream. The cancer story is interesting mouse biology that points both ways, and both posts told only the flattering half.
↑ back to summaryRewritten Sep 2026 from the earlier stub, and now listed on both the Nutrients and Supplements indexes. All references were checked against PubMed. Refs 9–15 were added on 28 Sep 2026 for the X-claims section; the UCLA paper's dosing (injection, 10.5 mg/day) and the absence of a dendritic-cell depletion experiment were checked against its full text on PubMed Central. The summary of Loo 2015 (ref 12) comes from the paper as it's usually described; its abstract wasn't re-read in this pass. The Kreider position stand's authors include people with supplement-industry consulting ties, as the paper discloses. The creatine-content-of-food, 20–40% muscle-store and 10 g brain-dose figures have no numbered citation yet. This page also answers the Metabolic Health hub's TODO about promoting creatine: the evidence supports treating it as the top-tier supplement.