The safety of creatine, a legal substance widely used by gym-goers and sportspeople, has been called into question after the former teammate of a New Zealand rugby player linked it to his death.
Johan Lomu, a former All Blacks player, died aged 40 in November 2015 after being diagnosed with a rare kidney disease.
Joeli Vidiri, a fellow former New Zealand player, has claimed that creatine may have caused his kidney disease.
However, Dr John Mayhew, Lomu’s personal GP and the team doctor of the All Blacks, said that he did not believe Lomu took the substance.
So, should sports and gym enthusiasts – be they amateur or professional – be wary of the commonly-used supplement?
What is creatine, and who uses it?
Creatine is a naturally occurring acid that supplies the muscles with energy, and is believed to increase lean muscle mass, and help the body recover more quickly after exercise.
Unlike other enhancement supplements, it is legal, and is not considered a performance enhancing drug by the World Anti-doping Authority. This means professional athletes are allowed to use it.
It is highly popular among those who take part in weight training and power sports, as well as “stop and go” team sports such as football.
Scientists first linked it to performance enhancement in the 1970s. However, it has become particularly popular in the past decade, according to Lloyd Bridger, co-founder of the London Muscle personal training group.
Over a third of English professional footballers use creatine, as well as a large number of young boys and men, according to Dr Pascale Kippelen, Senior Lecturer in Exercise and Respiratory Physiology at Brunel University.
Is it harmful?
“Creatine is one of the top selling nutritional supplements in the world,” says Carly Tierney a Personal Trainer at DW Fitness Clubs, adding: “It's safety and effectiveness has been supported in numerous peer-reviewed studies and many experts in the field of sports nutrition.”
Mirroring Ms Tierney's comments, Dr Kippelen says that it is considered suitable for users who are healthy, past puberty and do not exceed the recommended dose.
She adds that only anecdotal evidence links creatine to adverse side effects, and such cases are connected to pre-existing medical conditions, including kidney disease, as well as overuse.
However, further research is needed to determine the long-term effects of creatine use in humans, including potential links to asthma and the prevelance of the condition in professional athletes.
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Are there alternatives?
Nothing legal matches creatine when it comes to increasing muscle strength and power, as well as increasing capacity for high-intesnity exercise. However, some individuals are “non-responders”, meaning they will not experience any significant gains from the supplement, says Dr Kippelen.
"The direct effect of creatine on competitive performance in skill sports – such as football – remains questionable," she says.
Mr Bridger stresses that people should not be tempted by illegal performance enhancing drugs.
"Unfortunately when individuals strive to achieve great sporting accolades some will turn to illegal performance enhancing drugs and steroids which they will use in secret.
"Their use by athletes and bodybuilders has been shown to have severe effects on cardiovascular health, adrenal glands, gastro-intestinal system and, although rarer, kidneys."
Should I be worried?
Dr Kippelen stresses that creatine is safe, but "[recommends] the use of standard (8wk) courses of the supplement only at critical times of the sporting season and in association with heavy resistance training (to maximise muscle mass gain).
"Also, it important to remember that creatine is naturally present in diets including meats and fish (even if in smaller quantities than in the supplements); so, promoting a well-balanced, performance-enhancing diet to athletes is essential.""> Reuse content