Many world class competitors, college amateurs, and even adolescent athletes use creatine, a supplement available in health food stores, in an effort to build muscle.
Now a panel of experts from the American College of Sports Medicine has concluded that there is no evidence that creatine supplements increase the aerobic power of muscle.
While this unregulated dietary supplement is commonly perceived as safe, it is not for everyone and if used to excess may have the potential to cause harm, according to a report in the March issue of Medicine and Science in Sports and Exercise.
"It is viewed as relatively safe because it's a natural compound, but many natural or even essential nutrients can be troublesome in excess -- and one of the findings in the report is that the large amounts that are commonly consumed are not necessary, even if you want the benefits," Dr. Ronald L. Terjung, a professor of biomedical science at the University of Missouri.
Terjung was one of a dozen experts who met in Indianapolis in 1999 to assess the potential side effects of creatine, as well as its impact on energy levels, muscular development, and performance. The panel reviewed hundreds of studies on the subject.
They conclude that creatine may increase water retention in muscles -- thereby giving the feeling and appearance of increased muscularity -- but it does not take the place of weight-training as a means to increase muscle strength.
The supplement may help people with neuromuscular diseases, and may result in "small but significant" enhancement of performance in very specific exercise conditions. However the high expectations of creatine users seems to be "inordinate" given its small effect. The panel concluded that the supplement has no aerobic benefit at all.
The panel also found that there are many reports of muscular, gastrointestinal and cardiovascular problems -- including nausea, diarrhea, dehydration, hypertension, and cramping -- associated with creatine, though there is no definitive evidence that creatine is an unsafe or risky supplement.
However, the panel also emphasized that there is incomplete and insufficient data on creatine and "our lack of information cannot be taken as assurance that (creatine) supplementation is free from health risks."
Creatine should not be used directly before exercise, or by pregnant and lactating women or young children, the experts concluded.
In an interview with Reuters Health, Terjung noted that athletes should generally be cautious when using creatine because, like any dietary supplement, its use and contents are not regulated in the US Food and Drug Administration.
"You're trusting the quality control people at the manufacturing company, because there's no review process like there is with drugs by the FDA," he said.
In addition, Terjung said that even if creatine proves to be safe, its not clear if it is ethical to use a performance-enhancing substance.
"That's really the bottom line," he said. "Whether it gives a benefit isn't clear -- but in sports the perception is the most important thing, rather than facts. And the perception today is that it gives an edge. And the question is -- should the values of hard work and the ideals of competing be replaced by 'give me a quick fix so I can do better'?"
