What it is
Creatine monohydrate is the sports supplement with the strongest backing: in adults who train, it improves performance in repeated short, high-intensity efforts. It is one of the few with an authorised EU health claim: "increases physical performance in successive bursts of short-term, high-intensity exercise", for adults over 18 and with an intake of 3 g a day.
A very common mix-up at the counter: creatine is not creatinine. Creatinine is the waste product the muscle makes from creatine and that is measured in blood to assess the kidney. Taking creatine can raise creatinine without the kidney being any worse, and that needs to be known before a blood test.
What it does
Creatine is the muscle's fast energy reserve:
- It helps regenerate ATP in the first seconds of an intense effort (sprints, sets of weights).
- It shows in short, repeated efforts; it does not improve prolonged endurance performance.
- In the first weeks it holds some water inside the muscle: body weight rises 0.5-1.5 kg, and it is not fat.
At the counter
When to recommend it
- Healthy adults doing strength training or repeated intense efforts who want to try it
- Doses of 3-5 g a day in one go: no loading phase is needed
- Vegetarian or vegan diets: they tend to start from lower stores and respond more
When not to
- Under 18: the claim and most studies are in adults
- Pregnancy and breastfeeding: no data, better not
- Kidney disease or use of medicines that harm the kidney, unless their doctor advises it
Warnings
- Important KIDNEY: creatine raises serum creatinine without harming the kidney in healthy people, but it can distort the assessment of kidney function. Anyone with kidney disease should not take it without their nephrologist.
- Caution Not for under-18s, pregnancy or breastfeeding, for lack of safety data.
- Caution "Improved" forms (hydrochloride, buffered, etc.) cost more and have not been shown to beat monohydrate.
- Worth knowing Stomach upsets appear with large doses at once: splitting or lowering the dose solves it.
Pharmacokinetics
- Absorption
- Very good by mouth; no form is absorbed better than monohydrate, which is the best studied.
- Distribution
- About 95 % accumulates in skeletal muscle; the rest in brain and other tissues.
- Metabolism
- A small fraction (1-2 %) is converted spontaneously into creatinine each day.
- Elimination
- By the kidney, as creatinine, which is what the kidney function test measures.
Creatine and creatinine
| Aspect | Creatine | Creatinine |
|---|---|---|
| What it is | A muscle energy reserve, and the supplement | A waste product formed from creatine |
| Where it appears | In the diet (meat, fish) and in the supplement | In blood and urine |
| What it is looked at for | Performance in intense efforts | Assessing how the kidney is working |
| With the supplement | Rises in the muscle | Rises in blood without there having to be any damage |
They are different things: one is taken, the other is measured. Whoever takes the first should say so when asking for a blood test.
Self-assessment
Three questions. When you check your answers you will see the explanation for each one.
-
Creatine is converted into creatinine, so its blood level can rise even if the kidney is fine. It has to be said before a blood test.
-
Monohydrate is the best studied and no form has been shown to beat it.
-
Creatine is eliminated by the kidney and can distort monitoring of kidney function; in kidney disease, only with their doctor.
Training content. It does not replace the summary of product characteristics or clinical judgement.