Creatine: What Is Known About Muscles, Kidneys, and Promises for the Brain

Creatine can contribute to performance in short, intense efforts, particularly as part of strength training. It does not replace training, adequate nutrition, or sleep, and is not a general treatment for fatigue. Whether it suits you is a separate question from whether studies have found an average benefit.

The distinction matters in blood tests too. A review of creatine and kidney health, published on July 27, 2026, in International Urology and Nephrology, included 26 studies with 1,036 participants. Researchers found increased creatinine and a decrease in filtration estimates based on it, but no significant change in filtration measured using an external marker. This finding requires medical interpretation, not dismissal of an abnormal result.

What creatine does, and what it does not

According to the US National Institutes of Health's Office of Dietary Supplements, NIH, the body produces creatine itself and also obtains it from meat and fish. In muscle, it helps rapidly replenish ATP, a molecule cells use to supply energy.

This explains the activity in which its benefit is better established: repeated, short, high-intensity efforts. It does not mean that every activity improves equally or that someone who does not exercise will achieve the same results as a participant in a strength program.

Creatine is not an anabolic steroid, as clarified in the International Society of Sports Nutrition's 2021 review, nor is it protein. Protein supplies building blocks for bodily processes, so discussing a supplement does not replace examining meals. Further reading: how to include protein when you have no appetite.

Strength training is the context, not a minor detail

A meta-analysis published in Nutrients in 2024 found an average strength benefit in adults under 50 who combined creatine with resistance training. Results vary between studies and people; they do not promise a particular rate of progress or change in appearance.

A measured increase in lean mass is also not necessarily the same as an increase in muscle itself. Such measurements include water, and creatine can cause water retention and weight gain. A rapid weight change therefore does not prove new muscle was built at the same rate.

Before attributing all progress to the supplement, ask what the training program looks like. Is it consistent? Is the load appropriate? Is there enough rest and food? These are basic questions even for someone who chooses not to use a supplement at all.

Women and older adults: do not transfer results between groups

Most participants in the 2024 meta-analysis were men. With less data on women, caution is appropriate when estimating the effect size for them. This does not prove that women cannot benefit, but neither does it support a special promise for women.

Studies in older adults mainly examined creatine alongside activity and resistance training. A review published in European Review of Aging and Physical Activity in 2025 found a strength benefit, but the body-fat-percentage finding was not stable in sensitivity analysis, and there was no significant benefit in bone density.

This does not offer a shortcut to preventing falls, replacing rehabilitation, or treating loss of function. Particularly in older age, underlying conditions and medications matter. What was studied in healthy people who exercise should not automatically be assumed suitable for everyone.

Creatine and creatinine: similar names, different roles

Creatinine is a breakdown product used, among other things, to estimate kidney function. Creatine consumption can affect its level and therefore calculations based on it. The blood-test number alone does not explain what happened to the kidney.

A review published in BMC Nephrology in November 2025 found a small creatinine increase without a significant change in the filtration rate examined in the studies. The July 2026 review clarified why distinguishing between assessment methods matters. Both have limitations involving follow-up duration, populations, and measurement methods.

This does not mean creatine is "always safe," or that every creatinine increase was caused by it. Tell your doctor about supplements before testing and when interpreting results. The doctor will decide whether further tests are needed; do not dismiss an abnormal result or change treatment yourself.

The brain: a research field, not a proven promise

A meta-analysis published in Frontiers in Nutrition in 2024 and corrected in 2025 found signals of benefit in some cognitive measures, but not consistent improvement in every domain. Certainty varies, and results depend on the included studies and tasks.

In a November 2024 opinion, EFSA concluded that a causal relationship sufficient to substantiate the cognitive-improvement claim under review had not been established. The two works differ in their questions and assessment methods, but together they provide good reason to avoid promises of improved memory or dementia prevention.

A finding in one area of thinking does not prove an effect on everyday functioning over years. Someone experiencing memory decline or unusual fatigue needs an appropriate evaluation, rather than assuming a supplement studied in others will solve the problem.

Who needs a professional conversation before use

Kidney disease, unclear kidney function, diabetes, pregnancy, or breastfeeding require prior consultation. So do adolescence and taking diabetes medication or several regular medications together. Cleveland Clinic emphasizes reviewing underlying conditions, goals, medications, and supplements before deciding.

Digestive side effects, including nausea or diarrhea, can also occur. They should not be accepted as a necessary price of training. If symptoms appear, contact a professional to assess the connection and next steps. This article provides no dosing instructions or personal usage plan.

Product quality is a separate question from the ingredient's effectiveness. In the United States, NIH explains, supplements do not receive premarket approval for efficacy the way drugs do. According to its information sheet, sports supplements may contain ingredients that are not properly declared. Independent quality testing can reduce uncertainty about contents, but does not prove the product will benefit you and is not equivalent to approval of a drug's efficacy. Further reading: questions to ask before buying dietary supplements.

Ultimately, the useful conversation is not "which supplement is best," but what the goal is, what is already being done to achieve it, and what suits your health. Alongside that planning, strength training with a sensitive gut is part of the broader picture of sustainable activity.

This is general news information and is not a substitute for personal advice from a doctor or dietitian.