This study has investigated an interesting question that few other studies have explored in humans: does creatine intake affect cancer risk?

On one hand, it would not be surprising if higher creatine consumption — quantified in this study via meat intake — was associated with an increased risk of cancer. This is because red and processed meats are major sources of creatine and a number of studies have found that a higher intake of these foods is associated with a higher risk of cancer.^[1]

However, creatine is also found in other meats, including poultry and fish. And in most cohort studies, when the analyses are adjusted for important health behaviors like physical activity, smoking, and alcohol consumption, there is typically no association between intake of animal foods generally, or poultry or fish specifically, and cancer mortality.^[1]^[2]^[3]^[4]

The researchers in the summarized study also adjusted for several important potential confounders and found an interesting association: higher creatine intake (again, as obtained from meat) was associated with a reduced odds of having cancer. However, it is important to note that the summarized study examined the risk of having been diagnosed with cancer, versus many of the previous large studies that investigated cancer mortality (i.e., dying from cancer).

Only one other study specifically investigated creatine intake and its association with cancer. Like the summarized study, it used a cross-sectional design and a population that was both similar but partially the same. The participants were part of the 2017–2020 NHANES study, whereas the summarized study included participants from the 2007–2018 NHANES. The researchers reported a similar relationship to the summarized study, in which higher consumption of creatine was associated with a lower odds of cancer. Specifically, the participants in the top 50th percentile of creatine consumption group had an 18% lower odds of having cancer compared to the participants in the bottom 50th percentile of creatine consumption.^[5]

Although few studies have explored creatine intake and cancer specifically, there have been a great many studies on creatine supplementation that assessed other outcomes, and some of these studies involved very high dosages (e.g., up to 30 g/day) and long durations (e.g., 5 years). A variety of populations have been examined, from participants with no apparent health conditions to participants with health conditions like diabetes and arthritis, and from infants to older adults. None of these studies have reported an difference in cancer risk in participants who were taking creatine compared to participants who weren't, although most studies were likely too short and had too few participants and to detect a difference in cancer rates.^[6]

One subgroup finding in the summarized study that is worth mentioning was that creatine had a relationship to cancer in participants older than age 51, whereas this relationship was not found in participants who were below that age threshold. Creatine intake might be associated with less cancer in older adults because older adults tend to have a lower dietary intake of creatine and protein, lower physical activity levels, and muscle loss. These factors are often associated with an increased risk of a number of health conditions and mortality risks.^[7]^[8]^[9] Fortunately, meta-analyses of randomized controlled trials with creatine supplementation and resistance training tend to find increased muscle mass and strength in older adults.^[10]^[11]^[12]^[13] It’s also possible that younger participants had such a low prevalence of cancer that the study was underpowered to detect an association of creatine with cancer in this age group.

There is some evidence from animal research that creatine might affect cancer risk, but the findings are decidedly mixed. For more on this topic, check out the FAQ on the Examine creatine page: Does creatine cause cancer?

One study in rats found that high-dose creatine supplementation slowed tumor growth,^[14] perhaps by supporting methylation pathways. Similarly, a study in mice also found that creatine slowed tumor growth, seemingly by improving the function of anticancer immune cells.^[15] Conversely, studies in mice with breast cancer and colorectal cancer found that creatine increased cancer metastasis and worsened survival,^[16] which might be due to creatine increasing cancer cell energy reserves.^[17]^[18] However, given the limitations of extrapolating from rodent research, whether these findings translate into humans is very uncertain.

One curious aspect of the summarized study is the fact that creatine intakes seemed to be fairly low compared to the dosages often given in clinical trials. The group who consumed the most creatine was estimated to be consuming only 0.24 grams per day. This is in contrast to how creatine is commonly supplemented at dosages of 3 to 5 grams per day, or 5 to 10 grams per day in larger people.^[6] Because creatine intake was very low, there could be a variable other than the creatine in meat that was having an effect on cancer risk.

Although meat provides a small amount of creatine, it also contains a variety of other nutrients that can affect health, like protein, vitamin B12, iron, zinc, and some of the B vitamins. And because this study included the consumption of fish and shellfish, creatine could have been a marker for a higher intake of nutrients like selenium, omega-3 fatty acids, and vitamin D. It’s possible that achieving adequate intake of these nutrients was actually responsible for the difference in cancer prevalence, but research is not definitive.

Does creatine intake affect cancer risk? Original paper