Creatine Beyond the Gym: What the Trials Show

What creatine is and where yours comes from

Creatine is a nitrogen-containing compound your body makes, mostly in the liver, kidneys, and pancreas, out of three amino acids: glycine, arginine, and methionine. Synthesis covers roughly half of what you use each day. Diet covers most of the rest, and the dietary half comes almost entirely from animal tissue.

A mixed diet with fish, poultry, and meat in it provides about half of daily creatine needs. In practice that means somewhere around 1 to 2 grams a day from food, and the number moves with how much animal food you eat. People on vegetarian or vegan diets have lower muscle creatine stores at baseline, which is one reason supplementation studies in vegetarians tend to show bigger effects than the same studies in omnivores.

About 95% of the body's creatine sits in skeletal muscle. The rest is in brain, heart, and other tissue, and that distribution is why the brain research exists at all.

What the sports evidence supports

The reference document here is the 2017 International Society of Sports Nutrition position stand, authored by Kreider and colleagues and published in the Journal of the International Society of Sports Nutrition. Its core claims aren't subtle.

Creatine monohydrate is described as the most effective ergogenic nutritional supplement currently available for increasing high-intensity exercise capacity and lean body mass during training. Monohydrate is also called the most extensively studied and clinically effective form, and the position stand states plainly that no alternative form has been shown to be superior. That covers hydrochloride, ethyl ester, the buffered variants, and the rest of the alphabet.

On dosing, there are two routes. The fast one is about 0.3 grams per kilogram per day for 5 to 7 days, split into four servings, then 3 to 5 grams a day to hold the elevated stores. The slow one is 3 to 5 grams a day from the start, which raises muscle creatine over roughly three to four weeks. Both end up in the same place. Loading buys you about three weeks and costs you a week of gastrointestinal complaints that some people find unpleasant enough to quit over. Timing barely matters next to consistency. Creatine works through saturation, not through anything that happens in the hour after you swallow it, so rest days count.

Who paid for the position stand

The funding line says support to prepare the manuscript was provided by the Council for Responsible Nutrition, the US dietary supplement industry trade association. It also says the senior author prepared the update at that organization's request.

The competing interests section is long. The first author is a co-founder of the ISSN, has received industry-funded grants to run creatine research, serves as a scientific and legal consultant, and is a university-approved scientific advisor for a supplement company. A second author works for a contract research organization that's received grants from companies selling creatine, and sits on an advisory board for a brand that sells it. Several others report consulting or speaking income from the sports nutrition industry.

None of that means the performance findings are wrong. The ergogenic effect of creatine monohydrate is among the most replicated results in sports nutrition, and it predates this document by decades. What it does mean is that the most enthusiastic framing of the evidence comes from a document with industry money behind it, and the parts of that document reaching past sport into general health deserve a harder look than they usually get.

Looking past muscle: what the cognition trials measured

Two meta-analyses drive most of the brain claims, and the one you'll see quoted most is Prokopidis and colleagues, published in Nutrition Reviews in 2022. It screened 23 randomized controlled trials, included 10 in the systematic review, and put 8 into the meta-analysis. Pooled across those, creatine improved memory measures against placebo with a standardized mean difference of 0.29 and a 95% confidence interval of 0.04 to 0.53. Heterogeneity was high at 66%.

The subgroup result is where it gets interesting. In adults aged 66 to 76 the effect size was 0.88, confidence interval 0.22 to 1.55. In participants aged 11 to 31 it was 0.03, with an interval spanning zero. Dose didn't appear to matter across roughly 2.2 to 20 grams a day, and neither did duration across 5 days to 24 weeks. A separate meta-analysis covering 16 trials and 492 participants, ages 20.8 to 76.4, reported improvements in memory (SMD 0.31), attention time (SMD minus 0.31), and processing speed (SMD minus 0.51), with no significant effect on overall cognitive function or executive function. The review summarizing it rated the evidence moderate for memory and low for everything else.

That rating matters. Moderate and low aren't the same as established.

Where the cognition evidence is contested

In 2023, Nutrition Reviews published a letter from Eckert and Pascher titled, in part, "Double-counting due to inadequate statistics leads to false-positive findings." The target was the Prokopidis meta-analysis, and the argument was that the analysis handled multiple outcomes from the same trials in a way that inflated the apparent effect.

We're not in a position to adjudicate a statistical dispute, and neither is the marketing copy built on top of it. What a reader can reasonably take away is that the memory finding isn't settled, it comes from a small number of small trials, and there's an active published critique against it. If you see a product page quoting "creatine improves memory" without the confidence interval, it's quoting the version that survived the fewest checks.

There's also a mechanistic result worth knowing. In one study of older adults, 20 grams a day for 8 weeks raised total brain creatine by about 11%, measured directly. That's the clearest evidence that oral creatine reaches the brain at all, and it came at four times the maintenance dose.

The most consistent non-gym finding is in older adults

The strongest material outside sport isn't about cognition on its own. It's about creatine combined with resistance training in older adults.

A 2025 narrative review concludes that supplementation in that population, particularly alongside exercise training, improves lean body mass, muscle hypertrophy and strength, bone area and density, functional capacity, glucose metabolism, and memory retention. The framing matters. Creatine isn't doing the work of the training. It's making the training do slightly more. There's a related result that fits the same logic. Vegetarians taking 5 grams a day for six weeks improved working memory in one trial, which is what you'd predict if you start lower and have more room to move.

What the safety data actually covers

The position stand states there's no scientific evidence that short or long term use of creatine monohydrate has detrimental effects in otherwise healthy individuals at recommended doses. It also notes that clinical populations have taken 0.3 to 0.8 grams per kilogram per day, which is 21 to 56 grams a day for a 70 kilogram person, for years without clinically significant or serious adverse events.

The kidney question comes up because creatine breaks down into creatinine, and creatinine is the marker clinicians read kidney function from on a blood panel. Taking creatine raises serum creatinine. That's a measurement artifact of the supplement rather than evidence of kidney damage, and it's worth telling your clinician you supplement before a blood test so the number gets read correctly.

The longest direct safety evidence in older adults is thin. One two year trial in people with Parkinson disease using 4 grams a day found an increase in serum creatinine and no change in other kidney function markers. That's reassuring, and it's small. It isn't the same as a decade of data. Body weight goes up by roughly 1 to 2 kilograms in the first week or two. That's intracellular water, it's the expected consequence of muscle creatine saturation, and it isn't fat. If you weigh in for a sport with weight classes, plan around it.

Who should be careful

People with existing kidney disease should talk to their clinical team before supplementing. Not because harm has been shown, but because the research in that population is limited and the clearance question is real.

There's a specific drug interaction list worth checking. A 2025 review indexing creatine against a drug interaction database names pemetrexed, entecavir, cimetidine, trimethoprim, and probenecid as drugs whose serum levels may rise alongside it. If you take any of those, raise it with a pharmacist.

Data in pregnancy and breastfeeding aren't sufficient to make a call either way. Most clinicians recommend against supplemental doses in those periods for that reason, not because harm has been demonstrated.

What we cannot tell you

We can't tell you creatine treats anything. The position stand lists potential therapeutic applications in neurodegenerative disease, diabetes, and muscle wasting conditions as areas for further research, and in Parkinson disease specifically, early trials suggested short term symptomatic benefit while longer trials found no effect on disease progression.

We can't tell you which product to buy. We don't review branded products. The one quality issue specific to this category is that monohydrate is what the trials used, it's the cheapest form, and the expensive alternatives haven't been shown to beat it. Third party testing matters in a category with this much contract manufacturing behind it. We can't tell you the memory findings will hold. There's a published critique arguing they don't, and the trials behind them are small.

What this file can do is tell you which claims come from replicated trials, which come from a single meta-analysis with an active dispute attached, and how much of the safety picture has actually been measured.

Frequently asked questions

Do I need to load?

No. Loading saturates muscle in about a week instead of three to four weeks, and plenty of people find 20 grams a day unpleasant enough to stop. Stopping gets you nothing.

Does creatine hurt your kidneys?

In healthy people the evidence doesn't support that. Serum creatinine rises because creatine breaks down into it, so bloodwork looks different without the kidneys working differently. Existing kidney disease is a different situation and needs a clinician.

Is monohydrate really better than the expensive forms?

The position stand says monohydrate is the most extensively studied and clinically effective form and that no alternative has been shown superior. The alternatives cost more and have less behind them.

Will it help me think better?

The pooled trial data show a small improvement in memory measures, concentrated in adults over 65. The effect in younger adults was close to zero, and a published letter argues the analysis behind the headline finding was flawed.

How much weight will I gain?

Around 1 to 2 kilograms in the first couple of weeks, mostly intracellular water in muscle. It isn't fat, and it doesn't keep climbing.

Should I take it on rest days?

Yes. It works through saturation, so the dose that matters is the one you take every day.

Is it safe long term?

The data support safety at recommended doses, and clinical populations have used much higher doses for years under observation. The clean long term trials in older adults are few, so anything past a couple of years is thinly measured.

I eat a plant based diet. Does that change anything?

Probably. Lower baseline muscle creatine means more room to move, and trials in vegetarians have shown larger effects than equivalent trials in omnivores.

Does caffeine cancel it out?

One older study suggested high dose caffeine might blunt the ergogenic effect. The evidence is weak, and the practical answer is to take them at different times if it worries you.

---

This article is for general information only and does not constitute medical advice. Statements about dietary supplements have not been evaluated by the Food and Drug Administration and are not intended to diagnose, treat, cure, or prevent any disease. Talk with your health care provider before starting any supplement, especially if you take medication or have a kidney condition.

Sources

• International Society of Sports Nutrition position stand: safety and efficacy of creatine supplementation (Kreider et al., 2017)
• Creatine monohydrate supplementation for older adults and clinical populations (2025 review)
• Effects of creatine supplementation on memory in healthy individuals: systematic review and meta-analysis (Prokopidis et al., 2022)
• Creatine supplementation and exercise in aging: the muscle-brain axis (Frontiers in Nutrition, 2025)