Creatine has once again been dragged into supplement court, shoved into a metal folding chair beneath a flickering fluorescent bulb, and accused of crimes serious enough to make your tub quietly reconsider its legal representation.

For years, the usual charges were almost quaint:

Kidney destruction.

Dehydration.

Muscle cramps.

Hair loss.

The occasional claim that creatine will make your liver pack a suitcase, leave town, and start a new life under an assumed name in Witness Protection.

This time, however, the accusation is much heavier.

Creatine May Spread Cancer?

That sentence has enough emotional nitroglycerin stuffed inside it to send the entire fitness internet sprinting toward the nearest dumpster with a scoop in one hand and a GoPro in the other.

Before you fire your creatine into the backyard with a medieval trebuchet, let’s examine what the researchers actually found.

Mouse Data

A new study published in Nature Communications reported that supplemental creatine increased metastasis across several mouse cancer models involving melanoma, colorectal cancer, lung cancer, and breast cancer.

One melanoma experiment also showed shorter survival.

That deserves your attention.

It does not require you to run naked through Costco screaming that micronized monohydrate has joined an international crime syndicate.

The researchers traced the effect to megakaryocytes, the giant bone-marrow cells responsible for making platelets.

Platelets are normally the emergency road crew of your circulatory system. Slice your finger while opening a protein-powder package with a steak knife because apparently scissors are an insult to your ancestors, and platelets help plug the damage.

Useful little things.

Cancer, however, is very good at taking normal biology, stealing the keys, and using it for deeply unpleasant purposes.

Circulating tumor cells face a hostile trip through the bloodstream. Immune cells are looking for them. Mechanical forces are battering them around. Distant tissues are not exactly rolling out a welcome mat and handing them a complimentary cocktail.

Platelets can help.

They may surround tumor cells, shield them from immune detection, protect them from mechanical stress, and assist them in attaching to new tissue.

In this study, creatine increased signaling through a pathway involving creatine kinase B and STAT5B inside megakaryocytes. The resulting platelets became more reactive.

Creatine did not appear to create the cancer.

Instead, the data suggest it may have upgraded the escape vehicle for cancer cells already attempting to travel through the body.

Think less “creatine built the criminal” and more “creatine may have installed tinted windows, reinforced doors, and a suspiciously powerful engine in the getaway car.”

When the researchers disrupted this signaling pathway genetically or pharmacologically, the increase in platelet activity and metastasis was prevented in the mice.

That matters.

This was not one lonely mouse licking fruit-punch creatine off the laboratory floor while a graduate student updated LinkedIn.

The investigators used several cancer models, mechanistic experiments, genetic interventions, platelet testing, and pathway inhibition.

There is a real biological signal here.

Hooooman Data

This is the point where the headline climbs into a monster truck while the actual human evidence follows several miles behind on a child’s tricycle with one training wheel missing.

The human portion included eleven healthy adults.

They took 20 grams of creatine per day for 14 days.

After supplementation, some measures of platelet aggregation and adhesion increased.

Interesting?

Yes.

Proof that creatine makes human cancer spread?

Not even remotely.

The participants were healthy and cancer-free.

Researchers did not track tumor growth in humans.

Metastasis was measured only in mice.

Here is what happened next.

The scientists removed platelets from the volunteers and injected those platelets into immunodeficient mice alongside mouse melanoma cells.

Mice receiving platelets collected after creatine supplementation developed more lung metastases than those receiving platelets collected beforehand.

Read that sequence carefully because this is where nuance usually gets mugged behind a gas station and left without its wallet.

Healthy humans took creatine.

Their platelets were removed.

Those platelets were transferred into immunodeficient mice.

Mouse melanoma cells were also injected.

Metastasis was then measured in the mice.

That is a clever translational experiment.

It is not a clinical trial showing that creatine accelerated cancer in eleven people.

Anyone presenting it that way has taken the scientific method, duct-taped it to the hood of a Dodge Charger, and driven directly through a roadside billboard.

Actual Data

Creatine supplementation increased some measures of platelet reactivity in a very small group of healthy adults.

Platelets collected after supplementation promoted more metastasis when transferred into a specific mouse model.

A substantial series of experiments identified a plausible megakaryocyte CKB–STAT5B pathway that may explain the effect.

That is the finding.

No incense or screaming skull graphic need for the supplement executive slipping a suitcase of cash under the laboratory door.

Just an interesting and potentially important mechanism that now requires much better human research.

What The Paper Did NOT Show

This study did not demonstrate that creatine causes cancer in humans.

Cancer incidence was never measured.

Patients with active disease were not given creatine and followed for progression.

Researchers did not test long-term use of a typical maintenance dose such as 3–5 grams per day.

The experiment also cannot tell us whether a healthy lifter taking creatine faces any meaningful increase in cancer risk.

Mechanism does not automatically become outcome.

You can identify a pathway, map the signaling, watch the molecules dance beneath laboratory lights, and still have no idea whether the effect produces meaningful harm in an intact human being over months or years.

Biology is not a clean plumbing diagram.

It is a bar fight inside a power plant during a thunderstorm.

Every cell type has its own agenda, feedback loops start yelling over one another, hormones kick open side doors, and the immune system is wandering around with a clipboard trying to decide who gets removed from the building.

A mechanism can be real while the practical human effect remains tiny, context-dependent, or nonexistent.

At the same time, dismissing the study because it involved mice would be equally lazy.

This is not permission to slap the paper out of someone’s hand and yell, “Rodents!” as though you have completed peer review.

The work is mechanistically serious.

It raises a legitimate question about creatine, platelets, and metastatic biology.

That question now needs to be tested in people who actually have the disease, under clinically relevant conditions, with appropriate doses and meaningful outcomes.

Stop Creatine?

For a healthy lifter, this study does not provide enough evidence to panic-dump your creatine, bury it behind the garage, or perform a Viking funeral using your favorite shaker bottle.

My interpretation is far less dramatic:

This is a credible mechanistic warning signal based on this one study described above.

It is not proof that creatine causes cancer or accelerates metastasis in humans.

Someone with active cancer, metastatic disease, or ongoing oncology treatment has a different risk calculation than a healthy person trying to gain three pounds of muscle and finally deadlift without looking like a folding lawn chair.

In that setting, creatine belongs in a direct conversation with the oncology team, not a GooRoo from IG.

A YouTube thumbnail featuring four red arrows, a glowing tumor, and a man clutching his face like he just watched his accountant turn into a cobra is not a substitute for medical guidance.

For everyone else, keep the finding in perspective.

Do not ignore it.

Refuse to inflate it.

Science lives in the narrow, uncomfortable corridor between blind reassurance and full-volume panic.

That corridor is not flashy.

Nobody goes viral by standing there calmly holding a clipboard.

Unfortunately, it is where the truth usually lives.

The Complete Creatine Manual

Creatine has spent decades being blamed for dehydration, cramps, kidney damage, hair loss, and whatever other charge wandered into the supplement courthouse wearing mirrored sunglasses.

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Much love,

Dr. Mike

Reference

Xie, S., Chen, R., Sun, X., Ni, X., Wu, Y., Cai, L., Chen, Y., Lin, S., Rao, M., Chen, L., Li, Y., Xu, Y., Chen, M., Zhang, D., Zhu, S., Yang, L., Liu, W., Zuo, J., & Yang, Y. (2026). Exogenous creatine supplementation promotes tumor metastasis via megakaryocyte creatine kinase B–STAT5B signaling. Nature Communications. https://doi.org/10.1038/s41467-026-74639-z

Side note from Nature on this one "We are providing an unedited version of this manuscript to give early access to its findings. Before final publication, the manuscript will undergo further editing. Please note there may be errors present which affect the content, and all legal disclaimers apply."

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Mike T Nelson CISSN, CSCS, MSME, PhD
Associate Professor, Carrick Institute
Owner, Extreme Human Performance, LLC
Editorial Board Member, STRONG Fitness Mag

Mike T Nelson is a PhD and not a physician or registered dietitian. The contents of this email should not be taken as medical advice. It is not intended to diagnose, treat, cure, or prevent any health problem - nor is it intended to replace the advice of a physician. Always consult your physician or qualified health professional on any matters regarding your health.

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