Creatine Supplementation After a Cancer Diagnosis: What Do We Know?

Every time you scroll through social media, someone’s talking about protein (and yes, protein is important but don’t forget about fiber!) and now, creatine is everywhere too. Let’s break down the data- what we know and don’t know - and whether it is safe to take for people who have been diagnosed with cancer.

Creatine is a naturally occurring substance that is derived from three amino acids (methionine, glycine and arginine). The majority (95%) of it is stored in skeletal muscle (remainder is stored in the brain, testes and kidneys). In your muscles, roughly two-thirds of creatine is stored as phosphocreatine, which acts as a quick energy source to help recharge your muscles during short bursts of intense activity. Phosphocreatine provides phosphate for ATP, your body’s main energy currency, which is essential for muscle function. Supplementing with creatine can speed up the resynthesis of phosphocreatine, potentially improving strength and performance by helping your muscles recover faster between activity bursts.

In terms of diet, creatine is primarily found in red meat and fish—though in smaller amounts than what you’d get from supplements. There’s growing interest in creatine supplementation for vegans and vegetarians (who typically consume less dietary creatine), as well as for women, who also tend to have lower intake overall.

If you’re considering a supplement, the recommended form is creatine monohydrate. Other formulations exist, but they tend to be more expensive, may contain impurities, and haven’t been shown to offer additional benefits. Some people may experience temporary side effects like weight gain or bloating from water retention. Less commonly reported side effects include muscle cramping, GI upset, headaches, and nausea—but these aren’t consistently observed. Creatine supplements aren’t recommended for individuals with kidney disease, liver disease, or high blood pressure. It’s worth noting that up to one-third of people do not respond to creatine supplementation and will not increase creatine stores in muscle.

Who should take creatine?

The goal here isn’t to tell you whether or not you need it, but to share some of the existing data if you have been wondering whether you should take creatine. As always, check in with your health care team before starting any new supplement. Most of the current research on creatine comes from studies in athletes—primarily male athletes. A recent systematic review showed that overall, the evidence was inconclusive regarding the impact of creatine supplementation on performance in physically active women. Part of the challenge is that these studies vary widely in terms of populations, dosages, supplementation protocols, and levels of athletic ability, making it hard to draw strong conclusions. Some studies show improved strength and performance; others do not (and remember, creatine has been significantly understudied in females).

The decline in estrogen during menopause can contribute to declines in muscle mass, bone density, and strength. It has been suggested that creatine supplementation may help counter some of these effects. Studies have shown that creatine is more effective when it is combined with resistance training in postmenopausal women in terms of muscle mass, strength and functional performance. There’s a lot of interest on whether creatine can impact bone density and here the data is mixed as well. A study looking at two years of creatine supplementation and exercise in postmenopausal women had no effect on bone density but did show improvements in certain geometric properties at the proximal femur which can be indicators of bone strength. There is some concern that creatine can lead to an overestimation of lean body mass on DEXA scans due to increased water retention in muscles, potentially skewing body composition results (some recommend holding creatine supplements briefly before a DEXA scan).

There is also some evidence that creatine supplementation may have a small benefit on mood and cognitive performance, although more research and robust data is needed.

What about creatine and cancer?

There is not a lot of data on this topic. A very small study of 19 patients with breast cancer showed that seven days of creatine supplementation does not influence muscular performance. There is an ongoing study about a 16 week resistance training program in patients with breast cancer +/- creatine supplementation and I think this will be very helpful data once we have it. The THRIVE study is another ongoing trial looking at the benefit of exercise and creatine supplementation. A recent small study in prostate cancer did not show a benefit from creatine supplementation.

An article published in 2022 in the Journal, Trends in Cell Biology, titled “The two sides of creatine in cancer” discusses preclinical data in cell lines and mouse models where creatine helped suppressed cancer cell growth in some but also may have promoted cancer progression and metastasis in others. The data is clearly conflicting but we must remember that these are not human trials, we don’t know how supplementation would contribute to this (because our bodies already make creatine), what appropriate dosing is, and there are so many other confounding factors.

A recent study suggested that people who consume more creatine through their diet (this could have included people taking supplements) might have a lower risk of cancer. However, we need to be cautious when interpreting these study results. The researchers estimated creatine intake based on how much meat and fish people said they ate, and then asked if they had ever been diagnosed with cancer. But people with cancer may already be eating less red meat due to health recommendations, like those from the American Cancer Society, which could make it look like they had lower creatine intake—even if the lower intake came after their diagnosis.

What’s the bottom line?

Creatine is not for everyone but based on the data, it might be helpful for some people, particularly when combined with resistance training. Whether or not it’s right for you depends on your personal goals, health history and lifestyle. I recommend talking to your health care team before starting any supplements to make sure there is no potential harm. While there’s no strong evidence showing harm in people with cancer, data on benefits is still limited, and more studies are underway.

Let me know your questions on this topic! Do you take a creatine supplement? What has been your experience with it?