Does creatine actually work? What the evidence says about muscle, memory, and your kidneys

Creatine has become the supplement everyone on the internet wants to sell you, and the claims keep getting bigger. Brushing your teeth. Preventing Alzheimer's. Reversing memory loss. The actual evidence is narrower than the marketing, but in one area it's genuinely strong.

What creatine is and what it actually does

Creatine is a derivative of an amino acid. You get it from meat and seafood, and you store it in your muscles. It is not an essential nutrient. Your liver and kidneys make some of it on their own. But most people, even meat eaters, don't saturate their muscle stores through diet alone.

To understand why that matters, you have to think about how muscles use energy. The energy currency in your cells is ATP, and muscle cells can't store much of it. If ATP were all you had to work with, a contracting muscle would fail in about three seconds. Creatine solves that problem. Stored as creatine phosphate, it regenerates ATP on demand. It's less like fuel and more like a rechargeable battery sitting next to the muscle fiber. Supplementing raises the ceiling on how much your muscles can bank.

That same logic, cells that burn through ATP quickly, is why people also study creatine in the brain.

The muscle evidence is strong

This is where creatine earns its reputation. There are hundreds of randomized controlled trials in people doing resistance training, and on average, creatine supplementation lets you train closer to failure and gain more strength.

A recent meta-analysis in the journal Nutrients, looking at adults under 50 doing resistance training, found that people randomized to creatine could lift about 4.4 kg more on the bench press, roughly 10 extra pounds, and about 13 kg more on the leg press. That's not Arnold territory. It's real.

Two caveats matter. First, the benefit requires resistance training. Creatine plus sitting on the couch doesn't build muscle. The supplement lets you push slightly harder, and the harder training is what drives the gain. Second, the evidence in endurance athletes, runners and cyclists, is much weaker. That fits the biology. Endurance sports rarely push muscles to the kind of acute ATP failure where creatine's buffering matters most.

There is also solid evidence in older adults for mobility and fall prevention, which is not a trivial outcome.

The brain claims are far shakier

You will see influencers claim creatine reverses Alzheimer's, prevents cognitive decline, and should be mandatory for everyone. One recent viral clip described a "double blind, placebo controlled trial" at Kansas Medical School showing creatine reversed memory loss in Alzheimer's patients. That study exists. It is not randomized. It is not placebo controlled. It's 20 people with Alzheimer's who took creatine and got memory tested before and after. That's a very different thing, and without a placebo group, the result is close to uninterpretable. Placebo effects on performance and cognition are large.

The actual randomized evidence in neurodegenerative disease is sobering. A JAMA trial in 2015 randomized 1,700 people with early Parkinson's disease to 10 grams of creatine monohydrate daily for at least five years. It was stopped early for futility. A separate trial of 550 adults with Huntington's disease, using doses titrated up to 40 grams a day, was also halted for futility.

A 2018 meta-analysis of smaller trials in general cognitive performance showed a modest signal, mostly for short-term memory, and mostly in vegetarians. The effect is weak, inconsistent, and nowhere near what the influencer economy implies.

If creatine helps older adults cognitively, the most plausible path may be indirect: better muscle function, fewer falls, more engagement with the world, and a brain that benefits from all of that.

Dosing, water weight, and your kidneys

Most of the data uses creatine monohydrate. The fancier forms, like creatine ethyl ester, don't have evidence behind them and cost more. Five grams a day is a reasonable maintenance dose. Some bodybuilders do short "loading" phases at 20 to 40 grams a day, but that can cause GI issues, and the excess gets peed out anyway.

Expect some water weight. Creatine draws water into muscle cells via osmosis, and in the first week or two of supplementation you'll typically gain around 2 kg, roughly 4 to 5 pounds, of water. It persists as long as you take it and goes away when you stop. You're not stronger from the water, but your muscles may look slightly fuller.

Now the kidney question, because I'm a nephrologist and this one comes up constantly. Creatine does not harm your kidneys. What it does do is raise your serum creatinine, which is the blood test we use to estimate kidney function. Creatinine is a breakdown product of creatine, so if you eat more creatine, your creatinine goes up. This fools uninformed doctors into thinking kidney function has worsened when it hasn't. If you want certainty, ask for a cystatin C level, which estimates kidney function independently of creatine intake.

On hair loss: there is one small study suggesting creatine might raise a testosterone metabolite linked to hair loss, and several others showing nothing. Observational correlations between creatine use and hair loss are confounded by age, by the fact that the men most likely to take creatine are also the men whose hair was thinning anyway, and by undisclosed use of anabolic steroids in bodybuilding populations. Creatine also does not grow hair back. Sorry.

Bottom line

If you lift weights and you want slightly bigger gains, creatine monohydrate at 5 grams a day is well-studied, cheap, and safe. Expect a few pounds of water weight and a modestly higher bench press, not a transformation. If you're an older adult focused on strength and fall prevention, the evidence also supports it, paired with resistance training.

If you're taking it to prevent Alzheimer's or reverse cognitive decline, the evidence does not support the hype. The two large randomized trials in Parkinson's and Huntington's were stopped for futility, and the cognitive signal in healthy adults is small and inconsistent. It probably won't hurt you. It also probably won't do what the influencers promise.

Here's the "What's the deal with creatine?" segment from the episode:

I covered this in depth on Wellness, Actually, listen below.

Wellness, Actually Podcast

"What's the deal with creatine?" — Listen to the full episode, including the week's health news and listener Q&A.