Creatine is a strange case. It is simultaneously the most heavily researched supplement in the history of sports nutrition and the one most wrapped in folklore — the thing your gym buddy swears by and your brother-in-law swears will wreck your kidneys. Neither of them has read a study.

Strip away the noise and creatine is boring in the best possible way. It’s a naturally occurring compound your body already makes (about a gram a day) and stores in muscle. Supplementing it just tops up the tank — and the tank is what powers every short, explosive effort you make, from the last grinding rep on a squat to the sprint up a flight of stairs.

The short version: if you’re over 40 and training, creatine is the highest-return supplement you can take. Three to five grams of creatine monohydrate a day. That’s it. No cycle, no loading, no special-brand theatrics.

The long version is worth reading, because it’s where the two fears fall apart.

What creatine actually does (and why it matters more after 40)

Energy in a muscle cell runs on ATP. When you push hard — the last few reps of a set, a heavy hinge, a sprint — ATP runs out in seconds. Creatine’s whole job is to donate a phosphate so your body can regenerate that ATP faster, letting you push a little harder for a little longer before fatigue wins.

That “a little harder, a little longer” compounds. More work done in training is more stimulus for growth. Studies repeatedly find that people supplementing creatine while training gain more strength and lean mass than people training identically without it.

And here’s the thread that matters for the decade-scale reader: creatine’s benefits are amplified, not reduced, in an older body. The anabolic response to training is already blunted with age — the same workout synthesizes less muscle in a 55-year-old than a 25-year-old. Creatine is one of the few levers that reliably turns that dial back up. A 2025 meta-analysis pooling 20 randomized controlled trials and over 1,000 adults aged 55 and up found creatine plus resistance training produced significantly greater strength gains than training alone. The earlier Devries and Phillips (2014) meta-analysis landed on the same conclusion for older adults.

There’s also a cognitive thread worth naming, though you should hold it carefully: creatine is being studied for brain function — memory and mental fatigue, particularly under sleep deprivation or stress. The evidence there is promising rather than settled, mostly early and smaller trials. Bone density, by contrast, is the one place the enthusiasm has outrun the data: a recent large meta-analysis found creatine did not significantly improve bone mineral density, so strike that one off the “proven” list. That’s the point of checking rather than repeating — creatine’s case is strong enough on muscle and strength that it doesn’t need the weaker claims attached to it.

The two fears, examined

Every creatine skeptic reaches for one of two objections. Both are real-sounding. Both collapse under the evidence.

“It’ll damage your kidneys.” This is the big one, and it comes from a genuine clinical fact that got telephone-gamed into a myth. Creatine raises serum creatinine — a marker doctors use to estimate kidney filtration. That’s not damage; it’s just creatine doing its job, showing up in a blood test and mimicking a signal of poor kidney function.

The actual research on kidney function in healthy adults is unambiguous. Meta-analyses examining creatine supplementation find no adverse effect on glomerular filtration rate or kidney function in people with healthy kidneys. The caution that survives is narrow and specific: people with pre-existing kidney disease should avoid creatine, because their kidneys are already compromised. If your kidneys are healthy — and if you’ve ever discussed creatine with your doctor rather than your bartender — this fear does not apply to you.

“It’ll make you go bald.” This one traces, with suspicious precision, to a single 2009 study of twenty college rugby players, in which creatine loading shifted the ratio of testosterone to DHT (a hormone associated with male-pattern baldness). What that study did not do: measure hair loss. No participant lost hair. DHT stayed within normal range. And in the fifteen-plus years since, no study has ever replicated the effect. A 2021 meta-analysis of 22 studies and over 700 participants found creatine had no meaningful impact on testosterone or DHT at all.

The honest version: if you were already going to go bald, you were already going to go bald. Creatine is not the reason, and the evidence doesn’t support blaming it. If male-pattern baldness runs in your family and the theoretical signal bothers you, skipping creatine is a perfectly defensible personal choice — just understand you’re making it on comfort, not on data.

How to take it (the boring, correct way)

The supplement industry would love for this to be complicated. It isn’t.

  • Three to five grams of creatine monohydrate a day. Monohydrate is the form with the overwhelming bulk of the research behind it — which is also, conveniently, the cheapest. Skip the “buffered,” “HCl,” and “micronized” upsells; they charge more for the same molecule.
  • No loading phase needed. The old 20-grams-a-day-for-a-week protocol works but is unnecessary, and it’s the leading cause of the stomach cramps people blame on creatine. Steady daily dosing saturates your muscles in a few weeks and avoids the digestive drama.
  • Timing is irrelevant. Consistency wins. Mix it into water, your shake, or your morning coffee — the muscle doesn’t care what time the truck arrives, only that it keeps arriving.
  • Expect a little water weight. Creatine pulls water into the muscle cell, so the scale may tick up one to three kilograms in the first weeks. That’s intramuscular water — you’ll look fuller, not softer — and it’s a feature, not a bug. Don’t mistake it for fat gain. (If you’re tracking calories closely, see How Much Protein Do You Really Need? for the other half of the muscle equation.)

Because creatine draws water into muscle, stay on top of hydration — especially in a Hong Kong summer or any hard Hyrox-style session. Aim for roughly three liters a day and you’ve covered it.

The decade framing

No supplement replaces training, and creatine is no exception. Its benefit comes from letting you train harder — it amplifies the work, it doesn’t do the work for you. Take creatine, do nothing, and you get mild water weight and mild disappointment. Take it and train, and the evidence says you’ll be meaningfully stronger across your forties and fifties than you would have been without it.

That’s the shape of every argument worth making on a decade scale: the villain is the quick-fix industry, selling you a pile of mystery compounds with a six-week promise; the hero is the boring, evidence-backed lever that quietly compounds for years. Creatine is the rare supplement that lands on the right side of that line. It’s cheap, it’s safe for healthy kidneys, and it’s the single most-documented performance aid a man in midlife can put in his shaker.

Not because it’s magic. Because it’s one of the few things in the supplement aisle that actually stands up to being read.

Sources

  • Devries MC, Phillips SM (2014) — “Creatine supplementation during resistance training in older adults — a meta-analysis.” Creatine plus resistance training improved total body mass, fat-free mass, and upper/lower-body strength versus training alone in older adults.
  • Sharifian G, Aseminia P, Heidary D, Esformes JI (2025) — “Impact of creatine supplementation and exercise training in older adults: a systematic review and meta-analysis.” Eur Rev Aging Phys Act 22:17. Twenty RCTs, 1,093 adults aged 55+, creatine monohydrate plus exercise. Significant gains in 1-RM strength versus placebo (mean difference 2.12 kg, P=0.001). Bone mineral density was not significantly improved (P=0.557), and the body-fat effect did not survive sensitivity analysis — so the muscle/strength benefit is the one that holds.
  • Kreider RB et al. (2017) — International Society of Sports Nutrition (ISSN) position stand on creatine safety and efficacy. Confirms 3–5 g/day monohydrate as safe and effective for healthy adults; no adverse kidney/liver events in healthy populations.
  • Kidney function meta-analysis — Creatine raises serum creatinine but has no adverse effect on glomerular filtration rate in people with healthy kidneys; the caution applies specifically to pre-existing kidney disease.
  • van der Merwe J, Brooks NE, Myburgh KH (2009) — Clin J Sport Med. The single source of the hair-loss concern: a 20-participant study showing a DHT/testosterone ratio shift during loading, with DHT staying within normal range and no hair loss measured. Never replicated.
  • Antonio J et al. (2021) — Meta-analysis of 22 studies (>700 participants) finding no significant effect of creatine on total or free testosterone or DHT.