What it is
Creatine is the most studied sports supplement. That does not mean it works for everything you hear: it has one authorised health claim and good evidence in some uses, mixed results in others and a lot of noise on social media.
Authorised claim (EFSA): creatine increases physical performance in successive bursts of short-term, high-intensity exercise, in adults over 18 and at 3 g a day. Nothing else is a claim.
This pill orders the uses by level of proof, so you can answer honestly when asked about strength, the brain, hair or older adults.
How to sort what you hear
Four levels:
- WITH AN AUTHORISED CLAIM: performance in repeated short, intense efforts (sprints, weights) at 3 g a day in adults.
- A LOT OF EVIDENCE, NO CLAIM OF ITS OWN: gains in strength and muscle mass alongside strength training (consistent meta-analyses).
- STUDIED WITH PROMISING BUT LIMITED RESULTS: older adults (with strength training, muscle mass and strength), vegetarians and vegans (start with lower stores and respond more), cognitive function under load (sleep loss, stress) with mixed results.
- PRELIMINARY OR NO PROOF: low mood as an add-on to treatment, neurodegenerative diseases, pure endurance sports, "for weight loss".
At the counter
When to recommend it
- An adult doing strength training or short intense efforts who wants to try
- Someone over 50 who trains strength with a professional's indication, with known kidney function
- A vegetarian or vegan diet with sporting interest
- A trial of 4-8 weeks at 3-5 g a day, without loading
When not to
- Under 18: no claim applies and data are scarce
- Known kidney disease or low filtration without checking with the doctor
- Expecting a fast aesthetic or weight change: part of the early weight gain is intramuscular water
- Pregnancy and breastfeeding, for lack of enough data
Warnings
- Important CREATININE ON A BLOOD TEST: creatine raises creatinine without harming the kidney; the customer must tell their doctor before a test. To assess kidney function while on creatine, cystatin C is used.
- Important KIDNEY DISEASE: do not offer creatine without their doctor; a lab change can be mistaken for worsening.
- Caution NO CLAIM for brain, mood, older adults or hair: these are stated as studied, never as an effect that is promised.
- Caution UNDER 18: the claim does not include them and safety data are limited; do not recommend it.
- Worth knowing The weight gain in the first week is usually water in the muscle, not fat; explain it so they are not alarmed.
Pharmacokinetics
- Absorption
- Gut; good bioavailability as monohydrate. With a meal containing carbohydrate or protein, slightly better taken up by muscle.
- Distribution
- 95 % stays in muscle, as phosphocreatine; the brain holds less and takes longer to saturate.
- Metabolism
- Spontaneously converted to creatinine, which leaves through the kidney.
- Elimination
- Urine, as creatinine. That is why blood creatinine rises without the kidney being worse.
What can be said about each use
| Aspect | Can be said | Cannot be said |
|---|---|---|
| Short intense efforts | Authorised claim at 3 g a day in adults | That it works for any sport |
| Strength and muscle mass | Many studies alongside strength training | That it works without training |
| Older adults | Studied alongside strength training | That it slows ageing |
| Brain and mood | Mixed results, limited evidence | That it improves memory or mood |
| Hair | A small study measured DHT; it has not been replicated | That it causes baldness |
What has a claim, with its sentence; what has been studied, with its caution; the rest, nothing.
Self-assessment
Three questions. When you check your answers you will see the explanation for each one.
-
It is the only one EFSA lists.
-
It is an effect of the supplement; cystatin C is used to assess the kidney.
-
It is not recommended.
Training content. It does not replace the summary of product characteristics or clinical judgement.