The potential links between creatine and cancer are unclear. In general, evidence from in vitro studies and from studies conducted in animals suggests that creatine may have both cancer-suppressive and cancer-promoting properties.[1]
For example, in mouse models, both creatine and cyclocreatine (a synthetic analog of creatine) have been reported to slow down the rate of growth of subcutaneously implanted tumors.[2][3][4][5][6][7] The potential antitumor effects of cyclocreatine may require the presence of creatine kinase, through which cyclocreatine is converted to phosphocyclocreatine, which, in turn, potentially acts as an energy depleter by trapping ATP that has been released from the cell’s mitochondria or transported into the cell from outside, thereby limiting cancer cell proliferation.[4] However, because the expression of creatine kinase can vary widely depending on the type of tumor, the potential antitumor effects of cyclocreatine may also vary accordingly.[8] The potential antitumor properties of supplemental creatine may be related to its effects on cellular acidosis, inflammation, and oxidative stress,[5][7] as well as on the regulation of antitumor killer T cell immunity.[9]
On the other hand, findings from some studies suggest that creatine may promote invasion and metastasis of certain types of cancer — including colorectal cancer, breast cancer, and pancreatic cancer — through its energy-buffering properties and modulation of cell signaling.[10][11][12]
It’s important to highlight that the above findings are from in vitro and animal research, so their applicability to humans is currently unclear.
The limited available research in humans seems to suggest a potential protective role of creatine against cancer. Specifically, according to a 2023 cross-sectional study that was performed using data from 7,344 US adults who participated in the 2017–2020 National Health and Nutrition Examination Survey (NHANES), a higher intake of dietary creatine was associated with a lower risk of cancer or malignancy, with a 1% reduction in cancer risk for every additional milligram of creatine per kilogram of body mass consumed daily.[13] Moreover, in a 2006 randomized controlled trial, supplementation with creatine in people with colorectal cancer who were undergoing chemotherapy had no effect on muscle mass, muscle function, or quality of life, but improved biomarkers of nutritional status in a subsample of participants that were undergoing less aggressive chemotherapy.[14]
Overall, the available evidence from in vitro and animal studies suggests that creatine may suppress primary tumor growth, but promote invasion and metastasis of some types of tumor, with limited research in humans linking dietary creatine to a lower risk of cancer as well as to some minor protective effects in people undergoing mild chemotherapy for colorectal cancer.