Creatine and its effects: what the evidence supports for muscle and brain

You read three sentences about creatine online, and all three contradict each other. The first says it is almost as strong as doping. The second says it destroys your kidneys. The third says it makes you puffy and soft.

All three sentences come from people who mean well. And all three, exactly as they stand, are not what the data support.

Creatine is one of the most thoroughly studied dietary supplements we have. The expert group of the International Society of Sports Nutrition speaks of more than 500 peer reviewed publications on this single molecule. For comparison: with most products on the shelf we are talking about a handful of small studies.

That is exactly why an honest look is worth it here. Not to convince you. But so that you know what you are actually deciding about.

Creatine is not a muscle product. It is an emergency battery.

Picture a sprint over 30 metres. Or the moment you rip a heavy box up off the floor. Or that last repetition where suddenly nothing moves any more.

In those seconds something very special happens in your muscle cells. They burn ATP, the energy currency of the body. And the ATP supply inside the cell is tiny. It only lasts a few seconds of maximum work.

So why do you not collapse after two seconds? Because there is a second store sitting right next to it.

Part of the creatine in your cell is bound to a phosphate group. That is called phosphocreatine. When ATP is used up, phosphocreatine can hand over its phosphate group in a flash and make ATP again from it. No detour through oxygen, no detour through sugar. Direct.

Think of an emergency battery behind the wall socket. The main grid delivers continuously, but it needs a moment to start. The battery bridges exactly the seconds in between. That is precisely the role of phosphocreatine.

And now you know why creatine barely matters for marathon runners and matters quite a lot for sprints, jumps and strength training.

Where creatine comes from: liver, plate, and what has shifted

Creatine is not a foreign substance. Your body makes it itself, every day, without you doing anything for it.

The building blocks are three amino acids: glycine, arginine and methionine. Liver, kidneys and pancreas put roughly one gram per day together from them. The rest comes through food, above all through meat and fish. On a mixed diet the intake is roughly in the same range.

Around 95 percent of the creatine in the body sits in skeletal muscle. A smaller share sits in the brain, in the heart and in the retina. Every day part of it decays spontaneously to creatinine and is excreted through the kidney. That amount has to be replaced, otherwise the stores drop.

With that, the first honest consequence is clear: whoever regularly eats good animal foods has already covered a relevant part of this intake.

And still, the question of topping up is more justified today than it was fifty years ago. Not because supplements are fashionable, but because the conditions have shifted.

The share of meat in the diet is falling in many households, for good reasons. Vegetarian and vegan ways of eating are clearly more common. Both are a legitimate decision, but it changes creatine intake, because plants contain practically no creatine.

On top of that, heavily processed foods deliver a lot of energy and little nutrient density. It is also discussed whether chronic stress, environmental exposures and some medications can raise the consumption of protective and building substances. That is not specific to creatine, it holds for the whole field. The data on this are heterogeneous and in part methodologically disputed, and I would rather name that than skip over it.

And now you know why the most sensible first question is not “how much do I take”, but “what does my plate actually look like”.

Muscle and strength: what the meta-analyses show and what they do not

Now to the part most people care about. And here I would rather be precise than enthusiastic.

Creatine belongs to the few dietary supplements where several independent meta-analyses point in the same direction. It is just that the direction is more differentiated than advertising copy suggests.

It gets especially interesting in people who are not 25. Because from around midlife on we lose muscle mass continuously, and that is not a cosmetic question. Muscle mass is connected with fall risk, metabolism and independence.

And now you know why I do not find creatine most exciting in twenty year olds, but in people from midlife on who start taking their muscles seriously.

Monohydrate, expensive forms and the loading phase question

On the shelf you now find creatine hydrochloride, buffered creatine, creatine ethyl ester, creatine malate and a dozen further variants. They cost two to four times as much. And they promise better absorption.

A sober look at the literature gives a different picture.

The vast majority of studies that exist on creatine were done with creatine monohydrate. In the large meta-analysis on cognition with 16 randomised trials, monohydrate was even the only form used. Whoever buys a different compound is leaving the area where the data are.

The expert group of the International Society of Sports Nutrition took up exactly this question in their review of the most common misconceptions and places it accordingly: solid data for a superiority of other forms over monohydrate are missing so far.

The loading phase: faster yes, necessary no

The loading phase is the classic among creatine rituals. Five to seven days at 20 grams per day, split into four portions. It comes from one particular study, and that one is worth looking at.

A second research group in Western Australia investigated this further in 18 men. After five loading days the raised stores could be held over six weeks with 2 to 5 grams per day. Without a maintenance amount they dropped, but took longer than expected to come back to baseline.

One point of context that is missing from many texts: for dietary supplements in Germany, the Federal Institute for Risk Assessment names a maximum daily amount of 3 grams of creatine, which corresponds to about 3.41 grams of creatine monohydrate. The reference for this is listed in the sources at the end of this text. The higher amounts from the studies are research protocols, not a consumption recommendation.

And now you know why the surcharge for an exotic compound cannot be justified on the current data. That may still change, so far the comparative studies are missing.

Water in the muscle: the honest answer to the weight question

I know this thought well, it comes up again and again in conversations: two weeks of creatine, a kilo more on the scale, stopped straight away. And the observation is even correct.

Creatine is osmotically active. It can pull water with it. When you fill your muscle stores, water therefore probably comes along into the cell. That is not a side effect in the proper sense, it is a physiologically expected accompaniment.

The decisive question is not whether water is stored. It is: where.

One practical consequence still remains, and it deserves to be named honestly. If you compete in a sport with weight classes, one kilogram more is a real issue. And if your goal is a number on the scale, creatine will frustrate you in the first weeks.

The expert group of the sports nutrition society took up the question of water retention and fat gain explicitly in their overview of the most common misconceptions, together with the questions about hair loss, cramps and dehydration. It is worth knowing that list, because it shows one thing: most worries around creatine are old, often repeated and rarely tested.

And now you know why the scale is the worst advisor on this topic.

The lab value that startles you and often has a harmless explanation

This is the practically most important section of this article. If you take only one part with you, take this one.

Imagine you have been taking creatine for three months. You go for a routine check. And the report comes back: creatinine elevated. There is an arrow pointing up on the printout. Maybe next to it a comment about kidney function.

Your pulse goes up. Understandable.

Except: creatinine is nothing other than the normal breakdown product of creatine. Every day part of your creatine supply decays spontaneously to creatinine, and the kidney excretes it. If you carry more creatine in the body, arithmetically more creatinine arises. That can be plain arithmetic and does not have to mean kidney damage. But it cannot rule a kidney problem out on its own. That call belongs in medical hands.

A Brazilian group came to a similar picture in younger, healthy men. 18 participants received, randomised and double-blind, about 10 grams of creatine per day or placebo over three months, accompanied by moderate endurance training. Cystatin C dropped in both groups, which speaks for a better rather than a worse filtration performance. Other kidney parameters showed no meaningful differences.

A review on the renal safety of amino acid preparations in people doing sport sums it up like this: for creatine in a range of about 5 to 30 grams per day, no harmful effects on kidney function were found in people without pre-existing kidney disease. At the same time the authors call for more clinical data on the optimal duration and amount.

Honesty includes the other direction too. An elevated creatinine value can have many causes: too little to drink, a very hard training session shortly before, a lot of muscle mass, painkillers from the ibuprofen group, certain blood pressure medications. And sometimes it really is the kidney. So creatine is one possible explanation and never the end point.

And now you know why, with an arrow pointing up, you should first say what you are taking, and then look further together.

Brain, sleep loss and mood: the most exciting, thinnest part

Here it gets interesting, and here it gets uncertain at the same time. Both belong together.

One note first, because it counts legally and in substance: in the EU, only statements about physical performance are authorised for creatine. Everything that now follows on the brain and on mood is a report of studies and of the state of research. It is not a claim of effect and not a promise for you.

Your brain is an energy hungry organ. It makes up about two percent of your body weight and uses a disproportionately large share of your energy. And creatine sits there too, and the creatine kinase system buffers there too.

The obvious question: if I can fill up the muscle battery, can I do that in my head as well?

The answer is a careful “under certain conditions, maybe”.

A second, more recent meta-analysis with 16 randomised studies and 492 participants comes to a similarly differentiated picture. Memory, attention time and processing speed improved, overall cognition and executive function did not. In all included studies creatine monohydrate was used. The authors rate the certainty of the evidence for memory as moderate, and for all other domains as low.

One point belongs to honesty here: in the subgroups the two meta-analyses contradict each other. The first found the clearest effects in the oldest participants, the second in adults between 18 and 60 years, in women and in people with illnesses. That is another sign of how unfinished this field still is.

A systematic review of six randomised studies with 281 people describes hints of a better short term memory and better reasoning performance. In other cognitive domains the results contradicted each other. In young adults performance stayed unchanged. Vegetarians benefited more clearly in memory tasks than meat eaters.

Sleep loss: the state in which the most shows up

When you sleep too little, the energy reserves in the brain drop. Exactly here a line of research starts that I find exciting, without overrating it.

An older double-blind study in 19 people fits with this. After seven days with creatine followed by 24 hours of sleep deprivation with light exercise, several performances declined less strongly than under placebo: the ability to generate random movement, choice reaction time, static balance and mood state. Concentrations of catecholamines and cortisol in blood, by contrast, did not differ between the groups.

In animal experiments a related observation shows up. After four weeks of creatine, rats slept less during the rest phase, and the homeostatic sleep pressure after sleep deprivation was lower. That is an animal model. Nothing can be derived from it for humans, except the question of whether we are still missing something here.

Mood: signals, not answers

The connection between creatine and mental health is being discussed a lot at the moment. I consider it an honest example of what a field looks like in which nothing has been settled yet.

In an analysis of data from a large US health survey with 22,692 adults, the frequency of depressive symptoms in the lowest quarter of dietary creatine intake was 10.23 per 100 people, in the top quarter 5.98 per 100. After adjustment for numerous influencing factors an association remained. It was most pronounced in women, in people between 20 and 39 years and in people without antidepressant medication.

What matters is what this is not: a cross-sectional observation cannot prove a cause. People with higher creatine intake eat more meat and fish, and they probably differ in many further points from people with low intake.

From the clinical field there is one small randomised study: 18 people in bipolar depression received, on top of their existing therapy, 6 grams of creatine monohydrate per day or placebo for six weeks. In a verbal fluency test an advantage showed up for the creatine group, in the remaining neuropsychological tests it did not. The authors name the small sample size themselves as a key limitation.

And now the part that is missing from most texts. In the larger analysis by the same research group with 35 participants, two people switched into hypomania or mania under creatine early in the trial. In an older open study with ten people the same happened in both of the bipolar patients included.

And now you know why with “creatine for mental health” I neither wave it off nor cheer along.

The four lenses and the question that matters most

In clinical psychoneuroimmunology we look at a topic with four lenses. With creatine that nicely shows why a single building block never plays along at one place only.

Homeostasis: the body regulates in loops

And here comes the point that matters most to me with every dietary supplement.

Your body makes creatine itself. For that it uses up glycine, arginine and methionine. And it does not do that blindly, it regulates. The physiological review describes a metabolism that responds to intake. Whoever supplies from outside is intervening in a running control loop.

That is not an argument against creatine. It is an argument against the idea that a nutrient is a switch you simply flip. A nutrient is a player in a network. Whoever turns one screw moves others along with it.

With creatine the good news is: after stopping, muscle stores returned to baseline over weeks in these studies. A permanent shutdown of the body's own production is not described in these papers. So the body appears to pick this control loop up again.

Still, what holds for everything holds for creatine: eternal high dosing is not the goal. Once the store is saturated, more intake is unlikely to change much, the surplus is excreted. The loading studies point in exactly that direction.

The clearest example of this principle is not creatine, it is vitamin D. For covering a need the amounts are small. The German Nutrition Society gives an estimated value of 800 International Units per day for the situation where the body forms no vitamin D of its own. There are, alongside that, experimental approaches that use many times as much while monitoring calcium, parathyroid hormone and kidney values closely. I deliberately do not name concrete amounts or protocol names here.

I explicitly do not write this as a recommendation. Such approaches appear in no guideline, their benefit is not documented, and without medical supervision they can do serious harm, up to hypercalcaemia, kidney damage and cardiac arrhythmia. I do not offer them. Anyone with a chronic illness must under no circumstances stop or postpone a prescribed therapy because of this. I mention the principle only because it shows: the same substance, two completely different applications, separated only by dose, goal and monitoring.

With creatine the same principle looks like this: in the maintenance studies cited here the daily amounts sat in the low single digit gram range. That is closer to covering a need. The 4 grams per day over two years in the Parkinson study, by contrast, were a therapeutic research approach with close laboratory monitoring at six check-up appointments. The amount looks similar. The frame is a completely different one.

And now you know why with creatine I do not ask “yes or no”, but “what for, for how long, and how will you recognise that it was worth it”.

Three levers you can act on today

No protocol, no brands, no weekly plans. Just three things that lie in your hands.

And now you know why the most honest answer to “should I take creatine” is not yes or no, but starts with a question back about your goal.

Common questions about the effects of creatine

How this topic connects with the others

Creatine rarely stands alone. If you notice that one building block does not answer your question, these paths lead further.