A new preprint’s headline linking creatine to tumor metastasis overstates the evidence, experts said, stressing there is no proof creatine causes cancer in humans.
The study used mouse experiments and an 11-person human arm in which healthy volunteers took 20 g/day for two weeks; researchers reported “hyperactive” platelets that appeared to aid metastasis.
Susan Hewlings said the metastasis model was artificial because cancer cells were injected directly into mice’s bloodstreams, while the human sample was small, healthy and given a dose above typical long-term use.
Experts said the paper adds mechanistic insight but does not overturn creatine’s broader safety record, which includes years of use and prior reviews supporting safety in healthy adults.
They said the findings may warrant caution for people with a history of cancer and could inform clinician advice, but not broad claims that creatine drives tumor growth.