Study analysis · Nature communications · 2026
Your muscle-building supplement might be helping cancer spread, new study reveals.
Creatine supplements made cancer spread more in mice and made human platelets hyperactive, which could help cancer cells travel through the blood.
Overview
What the study found
The study in plain English — the bottom line, every takeaway we extracted, and what to do with them.
In simple terms
This study looked at whether taking creatine could make cancer spread faster. They tested it in mice and in a small group of people. In people, they only looked at changes in blood cells after taking creatine, not whether cancer actually spread. So we can't say for sure that creatine causes cancer to spread in people—we only have clues from mice and some changes in blood.
What’s the bottom line?
Creatine is a supplement many people take for muscle building. This study found that in mice, taking creatine made cancer more likely to spread to other parts of the body. It also made human blood platelets more active, which could help cancer cells travel through blood.
How strong is this study?
The study was done carefully in mice, with special genetic tricks to understand the mechanism. But the human part was not as well-controlled: there was no comparison group of people not taking creatine, and the researchers knew what they were giving. That means other factors could have influenced the results, so we shouldn't trust the human findings too much without more studies.
0 / 100
- COI disclosureconflicts of interest not disclosed
- Data availabilitydata not shared
- Code availabilitycode not shared
19 / 100
- Randomizationnot randomized
- Blindingblinding unclear
- Control group+15/15
- Sample sizeno sample size reported
- Follow-upno follow-up reported
100 / 100
23 / 100
- P-values+15/15
- Effect sizeno effect size reported
- Confidence intervalsno confidence intervals
- Pre-registrationnot pre-registered
Each component is scored out of 100 and then capped by the study design — a case series cannot reach the ceiling a randomised trial can, however well it is reported.
Where it sits
RCT reviewsReviews of RCTs (Meta-analyses)
Max 100Randomized TrialsRandomized Trials
Max 90Reviews of Cohort StudiesReviews of Cohort Studies
Max 85Cohort StudiesCohort Studies
Max 72Reviews of Case-Control StudiesReviews of Case-Control Studies
Max 63Case-Control StudiesCase-Control Studies
Max 58Cross-Sectional & Case SeriesCross-Sectional & Case Series
Max 50Expert OpinionExpert Opinion
Max 532 / 100
Probability of being correct
Snapshots of a population at a single point in time, or descriptions of small groups. Can identify correlations and prevalence, but cannot determine cause and effect.
This design cannot establish causation — the findings describe an association, not a cause. This study combines animal experiments and a non-randomized human intervention study without a control group. The human study is a before-after design, which cannot establish causation due to lack of randomization and blinding, and potential confounding factors. Animal studies provide mechanistic evidence but cannot directly establish causation in humans.
No Conflicts
No conflicts of interest identified
No conflicts of interest declared; study funded by government and academic grants; authors have no competing interests.
Funders
The study appears to be independently conducted with no industry funding or competing interests.
Key takeaways
- 01
Mice given creatine had more cancer spread (metastasis) and died sooner.
- 02
Human volunteers taking creatine had more active platelets.
- 03
This could mean people with cancer should avoid creatine supplements, but more research is needed.
Surprising findings
- Creatine promotes metastasis not by affecting tumor cells directly, but by activating platelets indirectly.Most people assume supplements either help or harm directly, but this shows an indirect effect through blood cells. Plus, creatine is usually seen as safe.
- Genetic or pharmacological blockade of the creatine pathway in megakaryocytes prevented metastasis in mice.This means that by blocking creatine's effect on platelets, cancer spread was stopped, suggesting a potential new anti-metastatic strategy.
Practical takeaways
If you have cancer or a strong family history, consider avoiding creatine supplements until more research is done.
This study is in mice and short-term human platelet measures, not long-term cancer outcomes in humans.
medium confidenceTalks to your doctor before taking creatine if you have any risk factors for cancer.
The study only looked at healthy volunteers and mice; no direct human cancer data.
high confidenceWhy this study matters
Creatine boosts cancer spread in mice
Mice given human-equivalent doses of creatine had significantly more tumor metastases and shorter survival. The effect was seen across multiple mouse models of cancer.
Creatine is one of the most popular supplements, used by millions to build muscle. This finding suggests a potential hidden risk for people with undiagnosed cancer.
The platelet connection
Creatine made platelets hyperactive by upregulating an enzyme called CKB in megakaryocytes, which then activated STAT5B signaling. This made platelets stickier and more likely to help cancer cells metastasize.
Most people think creatine works only on muscles, but this shows it directly affects blood cells in a way that could promote cancer spread.
Also happens in humans
Healthy volunteers who took creatine supplements showed increased platelet aggregation and activation markers in their blood, suggesting the same mechanism could increase metastasis risk in humans.
This moves the finding beyond mice to real people, making it relevant to anyone who takes creatine or knows someone who does.
Want the whole report?
Detailed mode opens the full scientific breakdown — every score component, the methodology, conflicts of interest, the evidence analysis behind each claim, and the raw study data.
Overview
What the study found
The study in plain English — the bottom line, every takeaway we extracted, and what to do with them.
Not medical advice. For informational purposes only. Always consult a healthcare professional. Terms
Creatine is a supplement many people take for muscle building. This study found that in mice, taking creatine made cancer more likely to spread to other parts of the body. It also made human blood platelets more active, which could help cancer cells travel through blood.
Research results
Mice given creatine had more cancer spread (metastasis) and died sooner. Human volunteers taking creatine had more active platelets.
What this means - more context
This could mean people with cancer should avoid creatine supplements, but more research is needed.
To investigate whether exogenous creatine supplementation promotes tumor metastasis and the underlying mechanism.
Creatine supplementation increases tumor metastasis in multiple mouse models and platelet hyperactivity in healthy humans. Mechanistically, creatine upregulates megakaryocyte creatine kinase B (CKB), leading to non-canonical STAT5B phosphorylation, which activates platelet functional genes and promotes hyperactive platelets. Genetic or pharmacological blockade of this pathway prevents metastasis.
Methods Used
Mouse models of metastasis (e.g., intravenous injection of tumor cells) with or without creatine supplementation; genetic knockout of Slc6a8 or Stat5b in megakaryocytes; pharmacological inhibition of STAT5; human volunteer supplementation study with platelet function assays.
Main Finding
Creatine supplementation at human-equivalent doses increases metastatic dissemination and reduces survival in mice, and induces hyperactive peripheral platelets in healthy volunteers, via megakaryocyte CKB-STAT5B signaling.
Confidence Level
High; supported by multiple in vivo mouse models, genetic and pharmacological loss-of-function experiments, and human data.
Study Flags
Red Flags
- •Human part has small sample size (not specified but likely)
- •Mouse models may not fully recapitulate human cancer
- •Only studied short-term, long-term effects unknown
Surprising Findings
Creatine promotes metastasis not by affecting tumor cells directly, but by activating platelets indirectly.
Most people assume supplements either help or harm directly, but this shows an indirect effect through blood cells. Plus, creatine is usually seen as safe.
Practical Takeaways
If you have cancer or a strong family history, consider avoiding creatine supplements until more research is done.
RCT reviewsReviews of RCTs (Meta-analyses)
Max 100Randomized TrialsRandomized Trials
Max 90Reviews of Cohort StudiesReviews of Cohort Studies
Max 85Cohort StudiesCohort Studies
Max 72Reviews of Case-Control StudiesReviews of Case-Control Studies
Max 63Case-Control StudiesCase-Control Studies
Max 58Cross-Sectional & Case SeriesCross-Sectional & Case Series
Max 50Expert OpinionExpert Opinion
Max 532 / 100
Probability of being correct
Snapshots of a population at a single point in time, or descriptions of small groups. Can identify correlations and prevalence, but cannot determine cause and effect.
Human Cross-Sectional
Subject
Lower probability
on the GRADE evidence scale
This study looked at whether taking creatine could make cancer spread faster. They tested it in mice and in a small group of people. In people, they only looked at changes in blood cells after taking creatine, not whether cancer actually spread. So we can't say for sure that creatine causes cancer to spread in people—we only have clues from mice and some changes in blood.
No conflicts of interest were detected in this study. No score impact.
Strengths
- Use of multiple mouse models with genetic knockouts and pharmacological inhibition to explore mechanism.
- Animal experiments include controls and demonstrate specificity.
- Human data provides some translational insight.
Weaknesses
- Human study is non-randomized, unblinded, and lacks a control group.
- Sample size for human component is not reported, likely small.
- Primary outcome in humans (platelet hyperactivity) is a surrogate marker, not clinical metastasis.
Methodology
Evidence Keywords
Statistical Reporting
Not medical advice. For informational purposes only. Always consult a healthcare professional. Terms
Creatine is a supplement many people take for muscle building. This study found that in mice, taking creatine made cancer more likely to spread to other parts of the body. It also made human blood platelets more active, which could help cancer cells travel through blood.
Research results
Mice given creatine had more cancer spread (metastasis) and died sooner. Human volunteers taking creatine had more active platelets.
What this means - more context
This could mean people with cancer should avoid creatine supplements, but more research is needed.
To investigate whether exogenous creatine supplementation promotes tumor metastasis and the underlying mechanism.
Creatine supplementation increases tumor metastasis in multiple mouse models and platelet hyperactivity in healthy humans. Mechanistically, creatine upregulates megakaryocyte creatine kinase B (CKB), leading to non-canonical STAT5B phosphorylation, which activates platelet functional genes and promotes hyperactive platelets. Genetic or pharmacological blockade of this pathway prevents metastasis.
Methods Used
Mouse models of metastasis (e.g., intravenous injection of tumor cells) with or without creatine supplementation; genetic knockout of Slc6a8 or Stat5b in megakaryocytes; pharmacological inhibition of STAT5; human volunteer supplementation study with platelet function assays.
Main Finding
Creatine supplementation at human-equivalent doses increases metastatic dissemination and reduces survival in mice, and induces hyperactive peripheral platelets in healthy volunteers, via megakaryocyte CKB-STAT5B signaling.
Confidence Level
High; supported by multiple in vivo mouse models, genetic and pharmacological loss-of-function experiments, and human data.
Study Flags
Red Flags
- •Human part has small sample size (not specified but likely)
- •Mouse models may not fully recapitulate human cancer
- •Only studied short-term, long-term effects unknown
Surprising Findings
Creatine promotes metastasis not by affecting tumor cells directly, but by activating platelets indirectly.
Most people assume supplements either help or harm directly, but this shows an indirect effect through blood cells. Plus, creatine is usually seen as safe.
Practical Takeaways
If you have cancer or a strong family history, consider avoiding creatine supplements until more research is done.
RCT reviewsReviews of RCTs (Meta-analyses)
Max 100Randomized TrialsRandomized Trials
Max 90Reviews of Cohort StudiesReviews of Cohort Studies
Max 85Cohort StudiesCohort Studies
Max 72Reviews of Case-Control StudiesReviews of Case-Control Studies
Max 63Case-Control StudiesCase-Control Studies
Max 58Cross-Sectional & Case SeriesCross-Sectional & Case Series
Max 50Expert OpinionExpert Opinion
Max 532 / 100
Probability of being correct
Snapshots of a population at a single point in time, or descriptions of small groups. Can identify correlations and prevalence, but cannot determine cause and effect.
Human Cross-Sectional
Subject
Lower probability
on the GRADE evidence scale
This study looked at whether taking creatine could make cancer spread faster. They tested it in mice and in a small group of people. In people, they only looked at changes in blood cells after taking creatine, not whether cancer actually spread. So we can't say for sure that creatine causes cancer to spread in people—we only have clues from mice and some changes in blood.
No conflicts of interest were detected in this study. No score impact.
Strengths
- Use of multiple mouse models with genetic knockouts and pharmacological inhibition to explore mechanism.
- Animal experiments include controls and demonstrate specificity.
- Human data provides some translational insight.
Weaknesses
- Human study is non-randomized, unblinded, and lacks a control group.
- Sample size for human component is not reported, likely small.
- Primary outcome in humans (platelet hyperactivity) is a surrogate marker, not clinical metastasis.
Methodology
Evidence Keywords
Statistical Reporting
Scoring
How strong is this study?
The study was done carefully in mice, with special genetic tricks to understand the mechanism. But the human part was not as well-controlled: there was no comparison group of people not taking creatine, and the researchers knew what they were giving. That means other factors could have influenced the results, so we shouldn't trust the human findings too much without more studies.
0 / 100
- COI disclosureconflicts of interest not disclosed
- Data availabilitydata not shared
- Code availabilitycode not shared
19 / 100
- Randomizationnot randomized
- Blindingblinding unclear
- Control group+15/15
- Sample sizeno sample size reported
- Follow-upno follow-up reported
100 / 100
23 / 100
- P-values+15/15
- Effect sizeno effect size reported
- Confidence intervalsno confidence intervals
- Pre-registrationnot pre-registered
Each component is scored out of 100 and then capped by the study design — a case series cannot reach the ceiling a randomised trial can, however well it is reported.
Where it sits
RCT reviewsReviews of RCTs (Meta-analyses)
Max 100Randomized TrialsRandomized Trials
Max 90Reviews of Cohort StudiesReviews of Cohort Studies
Max 85Cohort StudiesCohort Studies
Max 72Reviews of Case-Control StudiesReviews of Case-Control Studies
Max 63Case-Control StudiesCase-Control Studies
Max 58Cross-Sectional & Case SeriesCross-Sectional & Case Series
Max 50Expert OpinionExpert Opinion
Max 532 / 100
Probability of being correct
Snapshots of a population at a single point in time, or descriptions of small groups. Can identify correlations and prevalence, but cannot determine cause and effect.
This design cannot establish causation — the findings describe an association, not a cause. This study combines animal experiments and a non-randomized human intervention study without a control group. The human study is a before-after design, which cannot establish causation due to lack of randomization and blinding, and potential confounding factors. Animal studies provide mechanistic evidence but cannot directly establish causation in humans.
No Conflicts
No conflicts of interest identified
No conflicts of interest declared; study funded by government and academic grants; authors have no competing interests.
Funders
The study appears to be independently conducted with no industry funding or competing interests.
Standing
Who’s using this study?
The videos and claims on this site that lean on this study, and the researchers who wrote it.
1 video from Dr. William Wallace cite this study, drawing 2 claims from it.