WASHINGTON -- A dietary supplement that athletes use to build muscle might offer help to patients whose muscles are wasting away from such diseases as muscular dystrophy, a new study suggests.
Taking very large doses of creatine daily seemed to increase the strength of patients' muscles by about 10 percent, concludes the small study published Tuesday in the journal Neurology.
Independent scientists urged caution. The study was far too small and too short, lasting only a few weeks, to show if creatine offers lasting benefit or if high doses for long periods can cause side effects.
Plus, doctors actually tried to treat similar neuromuscular diseases with creatine in the 1950s, and it failed, said Dr. Audrey Penn of the National Institute of Neurological Disease and Stroke. So creatine was abandoned.
"I'm basically skeptical," Penn said. "I have a feeling that over the longer term it might not be such an exciting result."
But those 1950s studies only looked at whether creatine could cure or slow the disease, not if it had a smaller benefit like improving muscle strength and thus quality of life, Dr. Leon Charash of the Muscular Dystrophy Association said. The new study suggests creatine might do that, so Charash's association asked researchers Tuesday to start larger studies quickly and promised to help pay for them.
"If somebody can hold a glass up and not have somebody give it to them, that's a small gain -- but it's very important to that person," Charash said.
Creatine is an amino acid found naturally in healthy muscles. It has become one of the biggest-selling dietary supplements, thanks to athletes who hope it will build muscles.
There are no data that confirm the safety of taking extra creatine for long periods or at high doses, because the government allows dietary supplements to sell largely unregulated. Some athletes have reported muscle cramps, muscle tears and dehydration.
Because creatine is so widely sold, neuromuscular patients probably will race to try it for themselves, Charash said.
Separate research published last week in Nature Medicine already had patients of Lou Gehrig's disease excited. It was only a study in rodents, but it suggested that creatine might be more potent than the only prescription therapy for the disease, a killer neurological disorder that also attacks muscles.
In the study published Tuesday, Dr. Mark Tarnopolsky of Ontario's McMaster University gave 81 patients with a variety of neuromuscular diseases 10 daily grams of creatine for five days, followed by 5 grams a day for another week. When patients exercised their legs, hands and feet, they were a little stronger after the creatine than before.
Tarnopolsky noted that such patients naturally have lower creatine levels than healthy people and hypothesized that boosting their levels helped their muscle cells hang onto cellular energy supplies for a little longer.