Creatine Is a Multiplier, Not a Source

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What it actually is

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Creatine is a compound your body already makes, mostly in the liver, and tops up from meat and fish. Plants contain virtually none, so vegetarians and vegans run lower stores and often notice supplementation more. The supplement itself is synthesised, so it’s vegan-suitable.

Functionally it’s a rechargeable battery for short, explosive effort. Most of it sits in muscle, with a smaller but important amount in the brain. Two things happen with age: your body makes less of it, and most people eat less meat and fish. Stores fall exactly when they’d be most useful.

The muscle evidence is genuinely good

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This is where the case is strongest. Chilibeck et al. (2017) pooled 22 randomised controlled trials covering 721 older adults and found creatine alongside resistance training produced +1.37 kg lean tissue mass and greater gains in leg press and chest press strength than identical training with placebo.

A 2025 systematic review refines where it lands: the benefit is consistent for lean mass and lower-body strength, and equivocal for upper-limb hypertrophy. Legs respond; arms mostly don’t.

The critical qualifier: every one of those trials paired creatine with training. Without a training stimulus there’s nothing for it to multiply. It is not a muscle-building agent in its own right.

The brain evidence is narrower than the marketing

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Creatine does something measurable for cognition, and it is much smaller than the internet suggests. The reliable effects are on short-term memory and processing speed — not general reasoning, planning or problem-solving. The signal is clearest in the oldest adults and in states where the brain is under strain: sleep deprivation, illness.

Unlike muscle, this doesn’t require training. Keeping the brain’s energy buffer fuller is the whole mechanism.

It does not reduce dementia or Alzheimer’s risk. No trial supports that claim, and anyone making it is selling something. This distinction matters because “helps short-term memory in tired 75-year-olds” and “prevents dementia” get deliberately blurred in supplement marketing.

The kidney question, and the test artifact behind it

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Creatine monohydrate is among the most heavily studied supplements in existence, and in healthy people it has not been shown to damage kidneys or liver. The persistent fear traces back to a handful of old case reports rather than to trial evidence.

There is, however, a genuine measurement problem worth knowing. Creatine raises blood creatinine by roughly 10% — and creatinine is what eGFR is calculated from. So supplementing makes a perfectly healthy kidney look like it’s declining on paper. It’s an artifact, confirmed by other markers.

The practical fix is simple: tell whoever takes your blood that you supplement, or stop creatine about a week before a blood test. Otherwise you risk being investigated for a problem you don’t have.

Dose, and who should skip it

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3–5 g/day of plain creatine monohydrate. No timing requirement. No loading phase — the “20 g/day for five days” printed on tubs is unnecessary. Buy from a reputable manufacturer rather than an unknown marketplace seller, since purity is the one thing you can’t assess yourself.

Expect two minor effects: mild stomach upset if you take too much at once, and about two weeks of small weight gain that is water drawn into muscle, not fat.

Who shouldn’t take it:

• Reduced kidney function. Safety trials excluded people with existing disease, so there’s no good evidence it’s safe for an already-struggling kidney. The working threshold is an eGFR persistently below 60.
• Pregnancy.
• Anyone over 40–50 with existing medical conditions should check first rather than assume.

The honest proportionality

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The reason to be careful about the framing is that creatine sits at the far end of a very long queue. Resistance training, adequate protein, whole food, stable blood sugar and sleep do vastly more for both muscle and brain than any powder will.

The useful analogy is buying an aerodynamic cycling helmet while unfit. The helmet only helps once you’re fast enough for air resistance to be your limiting factor. Below that, the gains are all in the fitness. Creatine has the same shape: it multiplies a stimulus you have to supply.

Where that small edge becomes worth having is at the margin in an older body — the sliver of extra leg strength that decides whether a stumble on the stairs ends with a hand on the banister or a fractured hip. Framed that way, 1.37 kg of lean tissue and better leg press strength is not trivial at all. It’s just not a substitute for the training that earns it.

Summary

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Creatine is well-evidenced for muscle and narrowly evidenced for cognition. Pooled across 22 trials in 721 older adults it adds about 1.37 kg of lean tissue and meaningful lower-body strength — but only alongside resistance training, since it multiplies a stimulus rather than providing one. Cognitive benefit is limited to short-term memory and processing speed, strongest in the oldest and most stressed brains, and it does not reduce dementia risk. It’s safe in healthy people, requires no loading, and inflates blood creatinine by around 10%, which can make a healthy kidney look impaired on a test.

What to actually do:

1. Start resistance training first. Without it, creatine has nothing to act on.
2. Take 3–5 g/day of plain creatine monohydrate. Skip loading protocols and don’t worry about timing.
3. Tell the phlebotomist, or stop a week before bloods — otherwise expect a false kidney scare.
4. Don’t buy it for your memory. The cognitive effect is narrow and it does nothing for dementia risk.
5. Skip it entirely if your eGFR is persistently under 60, or if you’re pregnant.
6. Expect ~2 weeks of water weight and don’t read it as fat gain.

Education, not medical advice — check with your own doctor, particularly if you have kidney disease or take regular medication.

Sources & further reading

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• Chilibeck P.D. et al., Effect of creatine supplementation during resistance training on lean tissue mass and muscular strength in older adults: a meta-analysis, Open Access Journal of Sports Medicine (2017) — Taylor & Francis / PMC
• The impact of creatine supplementation associated with resistance training on muscular strength and lean tissue mass in the aged: a systematic review and meta-analysis, European Review of Aging and Physical Activity (2025) — Springer / PMC
• Devries M.C., Phillips S.M., Creatine supplementation during resistance training in older adults — a meta-analysis (2014) — ResearchGate
• Meta-analysis examining the importance of creatine ingestion strategies on lean tissue mass and strength in older adults — PMC