Creatine: the most-researched powder and the biggest misunderstanding about it

There is a white powder on my shopping list these days that sits there as naturally as bread, eggs and milk. Creatine. It used to feel like something for bodybuilders with big bags full of tubs. Now it simply joins the queue between the porridge oats and the yoghurt, as if it had always belonged there.

And it was precisely that ordinariness that made me curious. Because however ordinary this powder has become, there is a story behind it that runs far deeper than “it’s good for your muscles”. It is probably the most thoroughly researched supplement in existence. At the same time, it causes one of the most stubborn misunderstandings I know, a misunderstanding that makes many people stop taking it after a single blood test, often for no good reason at all.

What is creatine, really?

Creatine is not some strange, artificial substance. Your body makes it itself – mainly in the liver and the kidneys – out of the building blocks of proteins. You also take it in through food, especially meat and fish. Most of it is stored in your muscles, ready for use.

But to understand why creatine matters, we first need to meet the real lead character of this story: ATP.

ATP stands for adenosine triphosphate. You don’t have to remember that name; just remember what it does. ATP is the “energy currency” of your cells. Every muscle contraction, every heartbeat, every thought is paid for with ATP. When ATP releases its energy, a small piece falls off – a phosphate group – and what remains is ADP (adenosine diphosphate; “di” means two, “tri” means three, so ADP is simply ATP minus one phosphate). That loose phosphate particle is also called Pi, short for inorganic phosphate.

Here is something that almost sounds like science fiction. At any moment you hold only a tiny amount of ATP in store, and yet energy keeps flowing through you all day long. Not because you make so much of it, but because the same molecules are reused over and over again, many times per minute. Making energy, for us, is not about “making more”, but about recycling at astonishing speed.

The wallet, the coin jar and the bank account

This may well be the loveliest way to understand the system. Imagine your body has three kinds of money.

In your wallet are a few coins. Instantly available, but not much. That is ATP.

In your coat pocket is a small coin jar you can reach within seconds. That is creatine, or rather, its charged form: phosphocreatine (abbreviated PCr, simply “creatine with a phosphate attached”).

And in the bank account sits far more money, but it takes time to get to it. That is your glycogen (stored sugar) and your fat.

The role of creatine is now beautifully simple. During a short, explosive effort, a sprint, a heavy lift, your ATP runs almost dry within a few seconds. At that moment, phosphocreatine lightning-fast hands its phosphate back to ADP, and so ATP is formed again. It is a buffer of just a few seconds. That is why creatine helps most with short, powerful effort, and far less with a long endurance run.

The biggest misunderstanding about energy: the “high-energy bond”

Many articles write that ATP is “unstable”, or that energy is released “when you break a high-energy bond”. Neither is quite true, and this is exactly the part where I want to be strict, with myself and with you, because it is one of the best-documented misconceptions in biochemistry.

In reality, ATP is actually rather stable. Drop it into a glass of water and it does not fall apart quickly on its own. What makes ATP so useful is not that it is fragile, but that it has a high transfer potential: guided by enzymes, it can hand its phosphate to other molecules, and that is where usable energy is released.

And then the deepest point. Breaking a bond always costs energy; it never simply yields it. The energy comes from the whole reaction together: ADP and the loose phosphate, once surrounded by water, are jointly more stable and lower in energy than ATP was. That difference is what your cell can use. The energy does not sit “in a bond that snaps”, but in the shift from a less stable to a more stable state.

Why is that such a lovely insight? Because it shows how elegantly nature works. Evolution did not make a brittle, unstable molecule that leaks energy by accident. It made a stable molecule whose energy is released only when and where enzymes allow it. Not fragility, but control.

The quiet hero: creatine kinase

Here is a detail almost no one mentions. Creatine itself does rather little. The real hero is an enzyme called creatine kinase (often abbreviated CK).

CK decides within milliseconds what needs to happen. Is there plenty of ATP? Then CK takes a phosphate and attaches it to creatine, and phosphocreatine, the charged coin jar, is formed. Is ATP almost empty? Then CK hands that same phosphate straight back to make ATP.

So creatine is the battery. But creatine kinase is the clever charge controller that decides when that battery is charged or discharged. The battery without the controller would be useless.

One letter apart: creatine and creatinine

And now we reach the heart of this article. A confusion that occurs so often that I think this part, especially, may reassure a great many people.

Creatine and creatinine. One letter apart. But they are two completely different substances, with two completely different stories.

Creatine is a usable energy reserve. It helps your muscles and your brain.

Creatinine is a waste product. Your body can do nothing more with it and must clear it through the kidneys.

How does that waste arise? Beautifully, and very quietly. Creatine and phosphocreatine are not perfectly stable; every day, a small, fixed percentage of them spontaneously turns into creatinine. Not because an enzyme wills it, but because molecules simply break down slowly, like an elastic band that dries out over time. On average it concerns about 1 to 2 percent of your total creatine store per day. That is exactly why your body has to make new creatine daily, to keep the store topped up.

Worth pausing on: creatine tells the story of energy. Creatinine tells the story of clearing away.

Why doctors measure creatinine

Healthy kidneys filter creatinine out of the blood almost continuously. If the kidneys work less well, creatinine lingers longer in the blood and its concentration rises. That is why creatinine in the blood – serum creatinine – has for decades been a practical marker of kidney function.

But take note: it is a surrogate marker, not a direct measurement of the kidney itself. And it is influenced by far more than just your kidney function: by your muscle mass, your age, your sex, how much meat you eat, how well hydrated you are, intense training, certain medicines, and yes, also by creatine supplementation. Two people with exactly the same kidney function can therefore have different creatinine values.

That is why doctors nowadays usually also look at the eGFR. That stands for estimated glomerular filtration rate: an estimate of how much blood your kidneys can filter per minute, taking age and sex into account. (The GFR without the “e” is the actual filtration rate; the eGFR is the estimate of it.)

And there is another marker being used more and more often: cystatin C. This is a protein made by nearly all your cells, freely filtered by the kidneys, and, here is the elegant part, barely affected by muscle mass. Precisely in people with a great deal of muscle, or very little, where creatinine is hard to interpret, cystatin C can give a fairer picture. This marker is not perfect either (inflammation and other factors can play a part), but it often complements creatinine nicely.

The great misunderstanding: “my creatinine went up, so my kidneys are damaged”

And here is where thousands of people go wrong. The scenario is almost always the same.

Someone starts taking creatine. Weeks later they have blood drawn. The creatinine value is slightly higher. And the thought shoots straight up: creatine has damaged my kidneys.

But that need not be the case at all, and usually it isn’t.

Why not? Because you now simply have more creatine in your body. And because every day a small, fixed percentage of that creatine spontaneously turns into creatinine, your blood creatinine level can rise a little, while your kidneys filter exactly as well as before. The rise comes not from ailing kidneys but from a larger store of creatine. The scientific position of the international sports nutrition society is clear on this: an elevated creatinine due to supplementation does not, in itself, indicate kidney damage, and long-term use proved well tolerated in healthy people, even at high doses, over years.

So how do you know whether something is genuinely wrong with the kidneys? Not from a single creatinine value. A doctor looks at the whole picture: the eGFR, a urine test (for example protein or blood in the urine), how the values change over time, any symptoms, and sometimes additional markers such as cystatin C or imaging. A single laboratory value never tells the whole story.

Important, and honest: this concerns healthy people. If you already have a kidney condition, are pregnant or breastfeeding, or are under eighteen, discuss supplementation with your own doctor first. And if you are worried about a blood result, take it to your GP, who can place the value in the right context. That is precisely what this article does not replace.

Far bigger than sport: creatine and the brain

We tend to think of creatine in terms of muscles. But the brain may well be the most fascinating chapter of all.

Your brain weighs only about 2 percent of your body weight. Yet at rest it uses roughly 20 percent of all your energy. Why? Because neurons never take a break. Every thought, every memory, every emotion costs ATP. And so the brain, too, keeps a creatine and phosphocreatine buffer, just like your muscles.

What does that mean for your head? A 2024 review that pooled sixteen randomised trials (RCTs — studies in which participants are randomly given either creatine or a dummy treatment, the fairest way to measure an effect) found indications of a beneficial effect, particularly on memory. But the effects are small on average and not visible in everyone. Honesty is honesty.

And then the exam misunderstanding, which I would like to set straight. For a long time the thinking was: creatine never works acutely, so there is no point taking it just before an exam. That was largely true, creatine is not caffeine, it fills the store slowly over weeks. But recent research nuances this. In a 2024 study, a single high dose of creatine helped keep the brain’s phosphocreatine and ATP levels up during a night of sleep deprivation, while participants performed better on cognitive tasks and processing speed. So the honest, up-to-date phrasing is: at normal daily doses it builds up slowly, but under extreme strain such as sleep deprivation a single high dose appears to be able to do something. That is early evidence, not a routine recommendation.

In practice: what the research describes

A note first, because this matters: what follows is not personal advice, but a summary of what the scientific literature describes. For your own situation: consult your GP or specialist.

Which form? Creatine monohydrate. Not the newest, but the oldest, cheapest and by far the most studied form. There are dozens of pricier variants (HCl, “buffered”, ethyl ester and more), but there is no convincing evidence that, at an equal amount of creatine, they perform better than monohydrate. “Micronised”, by the way, is simply monohydrate, only more finely ground, so it dissolves a little better.

How much? The research usually describes around 3 to 5 grams per day to saturate the stores gradually. There is an optional “loading phase” (about 20 grams per day, split into a few portions, for five to seven days) that fills the muscle faster, but it is not necessary. With patience you reach exactly the same end point in a few weeks, often with fewer stomach and bowel complaints.

When? Surprisingly unimportant. Creatine does not work like caffeine, which “kicks in” within an hour; it slowly fills a store that your body draws on when needed. Consistency wins comfortably over timing. Taking it with a meal may support uptake a little, but the difference is modest. The best time is simply the moment you can keep up every day.

And the honest limit? Creatine replaces no training, no sleep, no protein, no rest. It enlarges one small part of a far larger system. Moreover, not everyone responds equally strongly: there are “responders” and “non-responders”, depending on, among other things, your baseline store (vegetarians often have more room for gain, because they take in less creatine from food) and your muscle type.

The deeper lesson

One extra letter separates energy from clearing away. Creatine and creatinine. It reveals something I actually find rather comforting: our body is not only about building and performing. It is just as much about maintaining, repairing and removing. A healthy body does all of those things at once, all day long, without us noticing.

Perhaps that is the loveliest lesson this white powder teaches us. Life is not about making endless energy, but about managing limited energy wisely, and about daring to trust the quiet systems that clear away and repair in the background.

And perhaps that reads beyond the body as well. How often do you, in your own busy life, rely on those calm maintenance processes in the background, the moments of recovery, the silent tidying-up, without even realising it?

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This article is intended for information and reflection, not as medical advice. If you have questions about supplements, about your kidney values or about a blood result, discuss them with your GP or a treating specialist, certainly if you have a kidney condition, are pregnant or breastfeeding, or are under eighteen.

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Sources

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