Creatine supplements – synthetic versions of a chemical found in muscle tissue – may benefit more people than just bodybuilders and athletes; they might also help women with fibromyalgia regain a little lost muscle strength, according to a new study published in the September issue of Arthritis Care & Research. But the study also found the supplements did little to help with overall fibromyalgia symptoms.

In the study, creatine improved muscle function in the upper and lower body of women with fibromyalgia by 6 percent to 10 percent on average, says senior study author Bruno Gualano, PhD, a professor in the School of Physical Education and Sport at the University of Sao Paulo, in Brazil. “It means that creatine can improve the patient’s physical capacity, which may be impaired in fibromyalgia.”

No one is certain what causes fibromyalgia – which results in fatigue, pain (especially muscle pain), sleep problems and sometimes brain fog – but it is thought to be due to abnormalities in central nervous system function, leading to an “amplification” of normal pain signals.

Some researchers also believe that one of the problems underlying the condition is muscle dysfunction – specifically, a problem with the storage and use of energy in muscle cells. Research has shown that muscle tissue in patients with fibromyalgia is low in both phosphorylcreatine (a creatine molecule that serves as an “energy reservoir”) and adenosine triphosphate (ATP), which is involved in the transfer of energy within cells.

In the 16-week study, 32 women with fibromyalgia were randomly assigned to receive either creatine (starting with 20 grams a day for five days, then 5 grams a day for the remaining time) or placebo that contained dextrose (a form of sugar). The study was double-blind, which means that neither the patients nor the researchers knew who was taking which substance. Muscle function was assessed by strength tests, including chest and leg presses and a handgrip press. Muscle phosphorylcreatine content was measured with an MRI.

“We observed that creatine supplementation can promote a substantial increase in muscle phosphorylcreatine,” says Gualano. “Creatine improves the transfer of energy, which ultimately results in better muscle functioning.”

The researchers had thought they would see improvements in fibromyalgia symptoms such as pain and fatigue, based on an earlier study that showed such benefits. That study used no control (placebo) group, and therefore is considered less reliable. “We speculated that creatine supplementation would result in improvements in clinical symptoms by increasing muscle function and, possibly, daily-living physical activity,” says Gualano.

But that didn’t happen.

“In view of the ‘negative’ results seen in our study, one may say our results were overall disappointing,” says Gualano. “While creatine may be of some assistance in recovering muscle function, especially if combined with exercise training, it is unlikely that this dietary intervention will positively impact general symptoms in fibromyalgia.”