Creatine is a substance found naturally in the body and in foods such as meat. It helps build muscle and aid recovery. In recent years, an increasing number of sports participants have been using commercially produced creatine, including the England World Cup football team.
Gary McAllister, the Coventry City and Scotland footballer, used creatine following last December's knee ligament damage that kept him from playing in the World Cup. He was playing again by September and believes creatine helped him recover more quickly. "It certainly allowed me to train longer, though there is a weight gain from it. You have to be in really strict training," he said.
Swimmer Mark Foster, a gold medal winner at this year's Commonwealth Games, said after using creatine: "Mentally I don't feel any different, but I do feel I've got more energy."
Doctors have found that heavy use of the substance can seriously aggravate hidden kidney problems, and also fear that extended use could lead to toxins being absorbed into cells because it encourages the body to absorb water.
Published reports have noted a number of adverse effects, including involuntarily clenched teeth, diarrhoea and "the sound of blood rushing in the ears". Furthermore, no long-term clinical test has been carried out to assess the use of creatine for more than a year - although Dr Annette Hudson, who has studied its effects, pointed out: "Anyone who is on a high-protein diet is on a high-creatine diet at the same time; that's the long-term natural study."
Creatine occurs naturally, in tiny amounts, in lean meat such as beef and pork, fish such as tuna, salmon, herring and cod, and loganberries. A 70kg (11-stone) person stores about 120g of creatine, almost all in the skeletal (rather than heart or intestinal) muscles. It can also be made by the liver using amino acids from proteins.
Creatine acts as a "reservoir" for extra energy in the muscle. To contract, muscles use their limited stores of a chemical called ATP. When that is exhausted, creatine is used to make extra ATP to extend intense bursts of energy. Furthermore, because it is stable within the body - unlike ATP, which must be used quickly once made - it can help recovery after intense exercise.
Dr Nick Pritchard and Dr Philip Kalra reported in The Lancet medical journal earlier this year the case of a man who was successfully treated for minor kidney problems eight years ago, but in June last year had high levels of creatine - which can indicate kidney stress. The man told the doctors he had been taking creatine supplements for eight weeks as part of his pre-season soccer training. Dr Pritchard commented that there was "strong circumstantial evidence" that the substance caused the man's renewed kidney difficulties.
Dr Hudson, who is a technical adviser to the Weider bodybuilding company, said: "You can overdose on anything, even headache pills. If you have a family history of kidney problems, discuss it with your GP: certainly if you do then using creatine will raise your blood pressure."
A parallel concern is that the muscles swell with water when they absorb creatine. Dr Ross Bailey, who heads the sports training department at Texas Christian University in Fort Worth in the United States, noted that: "Use of creatine tends to increase the permeability of the body's cells to certain toxins." He recommended that athletes should stop using it for four weeks after at most eight-weeks use.
Conor O' Shea, an Irish rugby union international, said: "We've been advised to go on it for a month or two and then off it for six weeks to make sure we're not at any risk from side-effects." He added: "It's certainly in the back of my mind that it does no good at all, but I'll give it the benefit of the doubt."
One who will not give creatine the benefit of any doubt is Andy Robinson, the coach at Bath rugby union club."I have read studies and taken advice from acknowledged experts and it seems obvious to me that more research needs to be done before athletes can safely take creatine supplements," he said.
Additional reporting: Chris Hewett, Phil Shaw
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The Coventry and Scotland international football captain has used creatine while recovering from a major knee injury. "The club doctor [at Coventry] has been fine about it. Basically they want you to take anything that's legal, which creatine is. People have said it helps recovery from little pulls and strains but I wouldn't use it for that. I used it for rehab."
One of Britain's most successful swimmers, the 1998 Commonwealth Games Gold medal winner endorses a creatine product. He says it gives him more energy. "Sport has gone so far with different training techniques and people are always looking for ways to perform better. I've definitely felt a difference, being able to train at a higher level. A lot of people have water retention [when on creatine] but I've had no ill effects."
Andy Robinson, rugby coach
The coach at Bath rugby club has forbidden his players from using creatine. "A number of coaches in Australia and New Zealand who once recommended creatine to their players have stopped doing so for the simple reason that not nearly enough is known about the long-term consequences of using it."
Arsene Wenger, football coach
Creatine use has been encouraged at Arsenal under the management of the Frenchman (left). The Arsenal players - many of whom took it during last season's Premier League and FA Cup Double-winning campaign - are among a wide range of footballers at club and international level to have used creatine
Conor O Shea
The Irish rugby union international uses creatine mainly in the off season during heavy training, and takes six-week breaks between courses to avoid side effects. "Creatine was introduced to me three or four years ago and it's something we've used much as a vitamin supplement would be. Physically I feel absolutely no different whatever. I'd never stand and advertise it and say it gives you a massive buzz.
Britain's most successful-ever sprinter was using creatine as far back as 1992, the year of his Barcelona Olympics 100m gold medal win. He is one of several prominent British athletes - including 110m hurdles world record holder Colin Jackson - who have said they have used the substance. Athletes are amongst the most frequent users, with 57 per cent having tried it and 44 per cent using it on a regular basis.Reuse content