Many people with chronic lower-back pain and osteoarthritis take glucosamine, a natural compound found in healthy cartilage, despite mixed evidence about whether it alleviates pain or disability. A study claiming to be one of the largest and longest trials of the supplement suggests that it does neither.

Some 125 Norwegian patients with lower-back pain and osteoarthritis were given 1,500 milligrams of oral glucosamine for six months, while a similar group received dummy pills.

The participants were evaluated for pain, pain-related disability, and quality of life at the beginning of the study, then at six weeks, three months, six months and a year.

Whether they were taking glucosamine or the placebo, their levels of pain, disability and quality of life were no different, researchers from Oslo University Hospital reported in the July 7 issue of The Journal of the American Medical Association.

“The most likely explanation for the outcome,” said an editorial by Dr. Andrew L. Avins of Northern California Kaiser-Permanente’s division of research, “is simply that glucosamine probably offers little benefit for chronic lower-back pain with osteoarthritis beyond whatever placebo effect it may provide.”