Wait, should I be worried about creatine now?

A deep dive into the research about cancer risk

Jun 24, 2025

I’ve always been wary of recommending supplements because:
1. I’m not a doctor or a nutritionist, so I don’t feel it’s my place.
2. Everyone’s biology is different, so blanket advice is rarely helpful.
3. There are so many conflicting opinions out there (between dieticians and medical professionals - never mind the mad influencers) that it can be hard to know what or whom to believe.

However, one supplement that I do feel comfortable recommending, as you know because I’ve mentioned it many times, is creatine.

Doctors and nutritionists that I respect have long sung its praises for improving energy, muscle strength, bone density and cognitive function - from Dr Federica Amati to Emma Bardwell to Dr Jenna Macciochi. So I felt on safe ground recommending it to you.

BUT when I shared an Instagram post about going on a Spanish retreat to celebrate the launch of Artah’s Essential Creatine (I know, it’s a tough job), I received a flurry of DMs from women who have been through breast cancer treatment and had heard that creatine can increase cancer risk. One even said her oncologist had warned against it.

Eeeeeek, obviously I don’t want to recommend anything that might increase cancer risk. I immediately put these concerns to Rhian Stephenson, nutritionist and founder of Artah, who did extensive research while working on the launch.

(Academic research lingo ahead 📣 please bear with me!)

“A large analysis of US adults (over 25,000 participants) actually found a significant negative association between dietary creatine intake and cancer risk,” says Rhian. “For every standard deviation increase in creatine intake, cancer risk decreased by about 5%.”

So, if creatine intake is associated with a lower risk of cancer, then where did this concern come from?

“Early concerns suggested that creatine supplementation might increase cancer risk by promoting the formation of carcinogenic heterocyclic amines (HCAs), which are mutagenic compounds,” she explains. “But a well-controlled human study specifically tested whether low or high doses of creatine, taken acutely or chronically, increased HCA formation. The results showed that creatine supplementation did not increase the production of these carcinogenic compounds in healthy subjects. Instead, dietary factors were found to be the main contributors to HCA formation.”

Those are the human studies, but there was one animal study that may have alarmed oncologists.

“One mouse study reported that creatine promoted liver metastasis in models of colorectal and breast cancer, highlighting the need for more nuanced understanding of context-dependent effect,” she says. “But it's important to understand trial dosages, because the mice were fed with food pellets containing 5% creatine by weight. When scaled to human-equivalent doses, this would correspond to approximately 560g per day for a 70kg adult - vastly higher than the recommended 3–10g per day for humans.”

Not only that, but other studies in mice have shown that creatine supplementation can enhance anti-tumour immunity. Mice given creatine were better able to suppress melanoma and colon cancer tumour growth and, in some cases, creatine combined with immunotherapy led to long-term protection against recurrence.

“Overall, current evidence does not support a cancer-promoting effect of creatine in humans, and some data suggest a possible protective effect,” Rhian summarises. “That being said, I would never advise someone with active or metastatic cancer to take creatine, nor any general supplement, unless they're working with an oncologist and nutritionist who specialise in cancer and integrated treatment protocols. There’s some evidence that creatine supplementation may have complementary effects with cancer treatment in preclinical models, but more research is needed to clarify its safety and efficacy in cancer patients.”