Creatine: The Most Boring, Best-Evidenced Supplement

If creatine were discovered tomorrow, it would be a terrible product. The effect is modest. The mechanism is unglamorous. It doesn't melt fat, reverse ageing, or "optimise" anything with a hormone in its name. All it does is what several hundred studies say it does — which, in the supplement industry, makes it almost unique.

That's precisely why it's worth writing about. Creatine is the best available answer to a question worth asking of any supplement: what does the evidence actually look like when something genuinely works?

What creatine is and what it does

Creatine is a compound your body makes — mostly in the liver and kidneys — and stores mainly in muscle, where it helps regenerate ATP, the immediate energy currency of muscle contraction. You also get some from meat and fish. Supplementation tops up muscle stores beyond what diet and synthesis typically achieve.

The practical consequence is small but reliable: a little more capacity for short, intense efforts. Across decades of trials, creatine supplementation combined with resistance training produces modest additional gains in strength and lean mass compared with training alone. Not transformation — addition. The International Society of Sports Nutrition, not an organisation given to understatement, calls it the most effective ergogenic supplement available for increasing high-intensity exercise capacity and lean body mass. The bar for that title is low, which is rather the point.

There's a quietly interesting frontier in older adults, where preserving muscle is less about aesthetics and more about staying independent: falls, fractures, and frailty all track with declining muscle strength. Trials of creatine plus resistance training in older populations show benefit on lean mass and some strength measures. The training is doing most of the work; creatine appears to help at the margin. That sentence — the training does most of the work — should be tattooed on the entire supplement conversation.

The cognition question

You will increasingly see creatine sold for the brain. The honest summary: the brain uses creatine, supplementation modestly raises brain creatine levels, and some small trials suggest benefits on certain cognitive tasks — particularly under stress conditions like sleep deprivation, and possibly in people with lower baseline stores, such as vegetarians. It's a genuinely interesting research area. It is not yet a reason to take creatine, and anyone selling it as a nootropic certainty is ahead of the data. Held lightly, watched with interest.

The kidney myth, and actual safety

The most persistent claim about creatine is that it damages kidneys. The origin is understandable: creatine supplementation raises creatinine, the breakdown product used as a blood marker of kidney function. The marker moves; the kidney is fine. In healthy people, studies up to several years long have not shown kidney harm at standard doses.

Two honest caveats. First, "healthy people" is doing work in that sentence — if you have kidney disease, that's a conversation with your own clinician before any supplement, this one included. Second, a raised creatinine in someone taking creatine can muddy genuine kidney function testing, which is worth mentioning to whoever orders your blood tests.

Beyond that, the side-effect profile is mostly mundane: a kilogram or so of water-related weight gain as muscle stores saturate, and occasional gastrointestinal grumbling at higher doses. The standard approach in studies is either a brief loading phase or, more simply, three to five grams of creatine monohydrate daily — the form with virtually all the evidence behind it. The fancier, pricier variants have marketing where their trials should be.

What creatine won't do

It won't help much if you don't train — the effect is an amplifier on resistance exercise, not a substitute for it. It does little for long, steady endurance work. A proportion of people are "non-responders," typically those whose muscle stores are already near-saturated from diet. And it will not address the things that actually dominate health outcomes: sleep, blood pressure, smoking, alcohol, activity, diet quality. No supplement does, which is the recurring theme of this entire section of the site.

One practical note on quality: supplements are not regulated like medicines, and contamination is a real phenomenon in the industry. Products certified by third-party schemes (such as Informed-Sport) reduce that risk — relevant for tested athletes and reassuring for everyone else.

Practical takeaways

• Creatine monohydrate, three to five grams daily, is the best-evidenced sports supplement in existence — and its effect is a modest addition to training, not a substitute for it.
• The kidney-damage claim is a misreading of a blood marker; in healthy people, the safety record at standard doses is good.
• Evidence in older adults doing resistance training is promising for preserving muscle and strength.
• The cognitive claims are interesting, early, and currently oversold.
• Buy boring: plain monohydrate, ideally third-party tested. The expensive variants are paying for adjectives.

What this doesn't mean

It doesn't mean everyone should take creatine. A supplement with good evidence is still optional — it sits at the margin of a training habit, not at the centre of health. And "well-evidenced for healthy adults" is not the same as "appropriate for you specifically."

When to seek medical advice

If you have kidney disease or reduced kidney function, are pregnant or breastfeeding, or take regular medication, speak with your GP or pharmacist before starting creatine or any supplement. And tell whoever interprets your blood tests that you're taking it — your creatinine will thank you for the context.

A closing thought

The supplement industry runs on excitement, and creatine offers none. Its trials are repetitive, its effect sizes are modest, and its mechanism has been understood for decades. That dullness is the signature of something real. When you next see a compound promising what creatine never could, ask to see its boring pile of consistent studies. There usually isn't one.

Further reading and sources

• International Society of Sports Nutrition — position stand on creatine supplementation
• NHS — information on supplements and healthy eating
• Peer-reviewed meta-analyses of creatine and resistance training in older adults (e.g. Chilibeck et al.)
• Informed-Sport — third-party supplement testing programme