How big the brain benefits are

The cognitive effects are plausible but the size, best dose and who benefits most (vegetarians? sleep-deprived?) are still being worked out.

Some people have naturally high muscle creatine and respond less; this varies and can’t be fully predicted.

Creatine, honestly — the best-evidenced supplement

Creatine is one of a tiny handful of supplements with strong, repeated human evidence — and it is cheap and safe for healthy people. Here is what it actually does, how to take it, and the myths worth dropping.

What it is

Creatine is a compound your muscles use to rapidly regenerate energy (ATP) during short, intense effort. Your body makes some and you get more from meat and fish; the supplement (creatine monohydrate) is the cheapest and by far the most-studied form.

What’s proven

More strength and muscle, with training — Consistent, repeated evidence that creatine plus resistance training builds strength and muscle — one of the few supplements that clearly works. It lets you squeeze out a little more hard work per session, which adds up. (established)
Cognitive and recovery benefits — Creatine is also present in the brain, and there are plausible, emerging signals for cognition (especially under sleep deprivation or in vegetarians) and recovery — promising, not settled. (emerging)

Myths worth dropping

“It’s just water weight / bloat” — The water is drawn into the muscle (intracellular), not bloat under the skin. That intramuscular water is part of how it helps. (note)
“It’s bad for your kidneys” — It does not harm healthy kidneys in the extensive evidence. Check with a clinician if you have kidney disease; otherwise it is very safe. (hype)
“You must load it” — Loading (20 g/day for a week) just fills the stores faster. A simple 3–5 g/day gets you to the same place within a few weeks. (note)

What we still don’t know

How big the brain benefits are The cognitive effects are plausible but the size, best dose and who benefits most (vegetarians? sleep-deprived?) are still being worked out.
Non-responders Some people have naturally high muscle creatine and respond less; this varies and can’t be fully predicted.

Key terms

Creatine A compound muscles use for fast energy; the best-evidenced strength/muscle supplement.
Phosphocreatine The stored form in muscle that rapidly regenerates ATP during short, intense effort.
Monohydrate The cheapest, best-studied form of creatine — no need for fancier versions.