Creatine, its safety and what the evidence shows

What creatine is and what it does

Creatine is a compound stored mostly in muscle, where it helps supply energy for short, intense effort. Supplements raise the amount stored in muscle, which helps explain the gains in high intensity exercise performance seen in trials [1].

In Great Britain, a label may say that creatine increases physical performance in successive bursts of short-term, high intensity exercise, for adults who train at that intensity, with the effect obtained at 3 g a day [2]. For adults over 55 who do regular resistance training, a label may say daily creatine can enhance the effect of that training on muscle strength [2].

What the evidence shows

A position stand from the International Society of Sports Nutrition concludes that creatine monohydrate is the most effective supplement available for increasing high intensity exercise capacity and lean body mass during training [1]. It is a sports nutrition society, so its view is best read beside independent reviews.

In older adults, a meta-analysis of trials in 357 people found that adding creatine to around 12 weeks of resistance training increased lean mass and some measures of strength and function more than training alone [3]. The authors noted that the number of studies was small, and that more work is needed [3].

The benefit is not confined to young men. Trials in young women and in women in their sixties have found gains in strength or physical performance with creatine compared with placebo [4].

Claims that creatine improves memory or concentration have been assessed for the Great Britain register and are listed as non-authorised [2].

The dose studied, and how it is taken

Studies support 3 to 5 g a day, which fills muscle stores over about 4 weeks [4]. A loading phase of about 20 g a day for 5 to 7 days fills them faster, and often adds 1 to 3 kg of body weight, mostly water [4].

Creatine monohydrate is the most extensively studied form, and the form with the clearest evidence for muscle uptake and performance [1].

Safety, and the kidneys

In healthy people, creatine at recommended doses has not been shown to harm the kidneys. A review of common questions found no adverse effect on kidney function in healthy adults at recommended doses [4], and an independent meta-analysis concluded that creatine did not cause kidney damage at the amounts and durations studied [5].

Creatine can raise blood creatinine, the marker laboratories use to estimate kidney function, so tell your doctor you take it before any kidney blood test [4]. The same review found the evidence does not support a link between creatine and hair loss [4].

Water retention is the side effect people most often notice, mainly in the first days of a loading phase, and longer studies have found that total body water stays in proportion to muscle [4]. Starting at 3 to 5 g a day, without loading, is likely to avoid most of that early change in weight.

Who should check with a doctor first

The ISSN position stand records the advice that people with kidney disease consult a doctor before taking creatine [1]. Speak to a doctor first if any of these apply to you.

• You have kidney disease, or a condition or medicine that affects the kidneys
• You take regular prescription medicines
• You are pregnant or breastfeeding
• You are considering a muscle building product that contains more than creatine

Choosing a product with care

Muscle building products carry a particular risk of hidden ingredients. In a review of US regulator warnings, 82 of the 92 adulterated muscle building supplements contained synthetic steroids or similar substances [6]. A product that contains creatine monohydrate alone, from a supplier you trust, is the simpler choice.

Questions to ask your doctor

A short conversation before you start covers the points that matter for you and your health.

• Is there any reason creatine is unsafe for my kidneys or with my medicines?
• Should we note it before my next blood test?
• What dose suits my training and my goals?
• How will we judge whether it is helping?

How The Wellness can help

A GP appointment gives you time to check creatine against your health and your medicines, and to plan any blood test so a raised creatinine is read correctly. Every doctor is GMC registered, and our clinics are on Baker Street in Marylebone and Eccleston Street in Belgravia.

If you and your doctor decide it suits you, our shop is there when you want it.