What Creatine Does: The Evidence and the Authorised Claims

Creatine is a natural compound that your body makes and also takes in from food. In the UK, creatine supplements are sold as food supplements. This guide explains what creatine is, which claims about it are authorised in Great Britain and under what conditions, what the register does not allow, and the safety points that reviews raise. It is general information, not medical advice. Our guide to choosing a creatine supplement covers the buying checks.

What creatine is

According to the ISSN's 2017 position stand on creatine, the body makes creatine, mainly in the liver and kidneys, from the amino acids arginine and glycine, and about half of the daily requirement comes from the diet, mostly from meat and fish. Around 95% of the body's creatine is held in skeletal muscle, where it plays a part in supplying energy for short, intense efforts. The position stand notes that vegetarians have lower muscle creatine stores on average.

The same source puts the amount the body replaces each day at roughly 1 to 3 g, depending on muscle mass, and says a pound (about 450 g) of uncooked beef or salmon provides about 1 to 2 g. The 3 g in the authorised claims is of the same order as that daily turnover.

The two authorised claims

In Great Britain only claims on the Great Britain nutrition and health claims register, published by the Department of Health and Social Care, may be used on food, and food supplements are food. The version we checked is dated 19 May 2026. It holds two authorised claims for creatine, both carried over from EU decisions taken before 2021 (Regulation (EU) No 432/2012 and Regulation (EU) 2017/672). The register applies in Great Britain; DHSC guidance says EU nutrition-claims rules continue to apply in Northern Ireland, so this guide describes Great Britain.

Claim 1: "Creatine increases physical performance in successive bursts of short-term, high intensity exercise."

• The food must provide a daily intake of 3 g of creatine.
• The consumer must be told that the beneficial effect is obtained with a daily intake of 3 g of creatine.
• It may be used only for foods targeting adults performing high intensity exercise.

Claim 2: "Daily creatine consumption can enhance the effect of resistance training on muscle strength in adults over the age of 55."

• It may be used only for foods targeting adults over the age of 55 who are engaged in regular resistance training.
• The consumer must be told that the beneficial effect is obtained with a daily intake of 3 g of creatine together with resistance training, performed at least three times a week for several weeks at an intensity of at least 65% to 75% of one repetition maximum, the heaviest load you can lift once.

The claims are narrow. Each names a specific effect, a group of adults, an amount of exercise and a daily dose. Neither says creatine helps everyone who takes it, and neither says anything about people who do not train.

In plain terms, the first wording is about repeated hard efforts with rests in between, such as sprint repeats or sets of heavy lifts, and the second is about older adults who already lift weights regularly. The register cites the scientific opinion behind the second claim (reference Q-2015-00437), so that is the place to look for the evidence its age limit and training conditions rest on.

How to check a claim on a label

• Does the wording match? The register authorises the wording above. A paraphrase that adds a result, such as "builds muscle", is a different claim.
• Does the product deliver 3 g of creatine a day? Both claims may be used only for food that provides that daily intake. If the recommended daily portion supplies less, the claim should not be there.
• Is the condition stated? The consumer must be told that the benefit comes with a daily intake of 3 g of creatine, and for the second claim with the resistance training described.
• Is it aimed at the right people? The first claim is for adults performing high intensity exercise and the second for adults over 55 who lift regularly.

What the register does not authorise

The same register lists, as not authorised, wording that is common on supplement pages. Claims that creatine supports the building of muscle, increases muscle power and speed, provides energy, enhances physical working capacity, improves mental attentiveness or improves cognitive function are all marked "non-authorised". So is the idea that creatine taken with carbohydrate increases muscle creatine stores.

That does not mean researchers have nothing to say about these topics. It means a label or advert in Great Britain cannot make those claims. If a tub or listing does, it has gone beyond the register.

What the research looks at

The research literature is wider than the register. The ISSN position stand reviews studies of creatine monohydrate in exercise, sport and medicine, and a 2024 follow-up question-and-answer paper from members of the society (Part II) revisits common questions. Studies in healthy adults mostly look at short, high-intensity efforts and resistance training, which is where the two authorised wordings sit. Research on other uses, such as brain function, is continuing. A society's position statement is not the same thing as an authorised label claim, and this guide does not promise any result. Several authors of the ISSN papers declare roles with creatine manufacturers, so read them alongside the regulator sources used here.

Safety: what the reviews say

The ISSN position stand concluded that there is no compelling scientific evidence that short- or long-term use of creatine monohydrate harms otherwise healthy people at the doses studied. The side effect that reviews report most consistently is weight gain, linked to a small amount of water held in the body. A 2021 paper by ISSN members concluded that creatine does not cause dehydration or muscle cramps. Those conclusions are about healthy adults; they are not advice for anyone with a medical condition.

Some people should talk to a doctor or pharmacist first:

• People with kidney disease. The position stand reports a suggestion that they consult a physician first as a precaution, and an NHS trust leaflet for people with chronic kidney disease who are not on dialysis says it is not advisable to take creatine. ISSN members also warn that creatine supplements can affect the blood creatinine readings used to judge kidney function, so tell your doctor you take it.
• People who are pregnant or breastfeeding, who take prescribed medicines or who have a diagnosed condition. The FSA advises checking with a GP or healthcare professional about any food supplement in these cases.
• People under 18, for whom the authorised wordings do not apply.
• Athletes who are drug tested. UKAD says there are no guarantees that any supplement is free from banned substances, and athletes are solely responsible for anything found in their system.

Using this when you shop

When you compare products, check that the creatine per serving is stated, that any claim matches the wording above including the 3 g condition, and that the label carries the standard supplement warnings, including not to exceed the recommended daily dose. The buying guide explains each check. Searches such as creatine monohydrate powder on Amazon (opens in a new tab) and creatine monohydrate Creapure on Amazon (opens in a new tab) show many listings, and the label on the pack, not the listing, is what counts.

For how much to take and when, see how to take creatine. Your GP or pharmacist is the right person to ask if you have a health condition or take medicines, and the label is the authority on dose and warnings.