Creatine Beyond the Gym: Strength, Brain and Healthy Aging

One of the most-studied supplements in sports nutrition

Creatine monohydrate has more than 25 years of research behind it and one of the strongest safety and efficacy records of any supplement (Rawson, GSSI Sports Science Exchange 2018; ISSN position stand). It is a compound your muscles and brain use to regenerate energy (ATP). More than 500 peer-reviewed publications have examined it (Antonio 2021), and the International Society of Sports Nutrition’s position stand describes both short-term and long-term use, up to 30 g a day for five years in some studies, as safe and well tolerated in healthy people and in a range of patient groups.

How it works, in plain words. Every muscle contraction and every nerve impulse spends ATP, and the cell has only a few seconds’ worth on hand. Creatine, stored as phosphocreatine, hands a phosphate back to spent ATP almost instantly. It is the fastest energy buffer the body has, but a small one, enough for seconds of all-out effort. The body makes some creatine itself and gets the rest from meat and fish, which is why vegetarians and vegans tend to start with lower stores. Supplementing raises muscle creatine by roughly 20 percent, most in people who start low, and more slowly tops up the brain pool.

What it reliably does: strength and muscle

Combined with resistance training, creatine reliably increases strength, power, and lean muscle mass, with the clearest effects over training blocks of 12 weeks or more. It is most useful for short, high-intensity efforts such as lifting and sprinting.

The effect size is modest but consistent. A meta-analysis of 22 randomized trials in 721 older adults (mean ages 57 to 70) who lifted two to three days a week for 7 to 52 weeks found that adding creatine produced 1.37 kg more lean tissue than placebo, with small extra gains in chest-press and leg-press strength (Chilibeck 2017). In younger lifters the position stand summarises the same pattern: better repeated high-intensity performance, so more work done per session, so larger training adaptations over time. Creatine does not build muscle by itself; it lets you train slightly harder. The broader picture of what drives muscle growth is covered in how to build muscle.

The expanding story: brain and aging

Newer research points beyond muscle. Brain creatine levels can be raised with supplementation, and studies suggest benefits for memory and mental fatigue, especially under stress or sleep deprivation (cognition RCT). In older adults, creatine combined with exercise shows promise for preserving muscle and physical function (older-adults review) - an active area of healthy-aging research.

The key trials, with their limits:

• Rae 2003. 45 young vegetarian adults took 5 g a day for six weeks in a double-blind crossover. Working memory (backward digit span) and reasoning (Raven’s matrices) improved significantly (Rae 2003). This is the study most creatine-and-brain claims trace back to.
• Sandkuhler 2023, the largest trial so far. 123 adults, about half vegetarian, took 5 g a day for six weeks in a preregistered crossover using the same two tests. The result was a small benefit at best: borderline on digit span (p = 0.064), none on Raven’s, none on eight exploratory tests. Vegetarians did not benefit more than omnivores, and side effects were reported four times as often on creatine as on placebo (Sandkuhler 2023).
• Sleep deprivation, single dose. In a 2024 imaging study, a single large dose of creatine monohydrate (0.35 g per kg of body weight, roughly 25 g for a 70 kg adult) taken at the start of a 21-hour sleep-deprivation night improved processing speed and cognitive performance at 3 to 7.5 hours, alongside measurable changes in brain energy markers on MR spectroscopy (Gordji-Nejad 2024). It is a single-dose mechanistic experiment using an amount far above normal supplementation, not a protocol.
• Memory meta-analysis. Pooling eight randomized trials, creatine improved memory measures overall (standardized mean difference 0.29). The effect was concentrated in adults aged 66 to 76 (SMD 0.88) and absent in 11-to-31-year-olds (SMD 0.03), across doses of about 2 to 20 g a day and durations of 5 days to 24 weeks (Prokopidis 2023). A published letter later argued the analysis double-counted some data, which may have inflated the result (Eckert 2023).
• Older adults and function. A 2025 meta-analysis of 20 trials and 1,093 older adults found creatine plus exercise training raised one-repetition-maximum strength by about 2 kg and lowered body-fat percentage by about half a point compared with exercise plus placebo, with no effect on bone mineral density (Sharifian 2025).

A fuller look at the cognition trials is in creatine and cognition.

Which form: monohydrate vs branded forms

Creatine monohydrate is the form used in nearly every study above. A 2022 critical review of the “novel forms” sold as upgrades concluded that monohydrate remains the only source with substantial evidence of bioavailability, efficacy and safety, and that the marketed alternatives were either less bioavailable, less effective, more expensive, or simply under-studied (Kreider 2022). Monohydrate is also the form professional societies recommend and the one approved as a food ingredient in major markets.

Who responds most, and who may not

• Older adults. The memory meta-analysis found its effect in the 66-to-76 age group and none in younger participants, and the two older-adult meta-analyses show consistent lean-mass and strength gains when creatine is added to training.
• Vegetarians and vegans. Lower baseline stores make a bigger rise plausible, and the classic 2003 trial was done entirely in vegetarians. But the 2023 trial, with 123 participants, found no extra benefit in vegetarians, so consider this unsettled.
• The sleep-deprived. The single-dose study points this way, but it is one experiment with a very large dose.
• People whose stores are already high. The largest rises occur in people who start low, so heavy meat eaters have less to gain.
• Women. The 2021 expert review finds accumulating evidence of benefit in females across the lifespan, with little to no side effects, and no basis for the idea that creatine only works in men.

Dosing and safety

• The approach used in most studies: 3 to 5 g per day, every day; timing does not matter much. A “loading” phase is optional and can cause stomach upset. In the research, loading (around 20 g a day for about 5 days) raised muscle creatine fastest; 3 to 5 g a day reached a similar level in about four weeks.
• The only consistent side effect is slight water-weight gain. Despite old myths, controlled studies show no kidney or liver harm in healthy people at recommended doses. A 2019 systematic review and meta-analysis of renal outcomes concluded that creatine did not induce kidney damage at the doses and durations studied (de Souza e Silva 2019).
• A practical wrinkle: creatine breaks down into creatinine, the marker used in routine kidney blood tests, so supplementation can nudge that number up without any change in kidney function. Tell the clinician ordering the test.
• Hair loss, dehydration and cramping are common worries; the 2021 expert review found that the evidence does not support any of them.
• If you have kidney disease, check with a doctor first.

Who should talk to a clinician before using it: anyone with kidney disease or a single kidney, people taking medicines that affect the kidneys (some anti-inflammatories, diuretics, certain blood-pressure drugs), anyone under 18, and anyone pregnant or breastfeeding, where safety data are thin. The guide to reading a supplement study explains why single small trials, like several of the brain studies above, should not be read as settled.

Where the evidence is weak

The strength data are solid. The brain data are promising but thin: the largest trial found a borderline effect, the main meta-analysis has a published statistical critique, the older-adult memory subgroup rests on few trials with high heterogeneity, and the sleep-deprivation result came from a single very large dose in one experiment. Nothing here concerns any diagnosed condition; those are separate research questions.

Bottom line

Creatine is cheap, safe, and genuinely effective for strength — and the brain and healthy-aging evidence is increasingly interesting. Across the trials, 3 to 5 g of plain creatine monohydrate a day was the standard amount, and the evidence base behind it is among the strongest for any supplement. Expect a real but modest edge in the gym, a possible small edge in memory if you are older or short on sleep, and skip the branded forms.