Glucosamine, a popular food supplement used by arthritis sufferers to prevent painful flare-ups, has no long-term benefit, Canadian researchers said on Wednesday.

The University of British Columbia researchers found that 45 percent of glucosamine users still suffered arthritis attacks during a six-month period, compared with only 42 percent who were given a placebo.

“Our study shows that even if the supplement was initially perceived by study participants to be helpful, it has no benefit for maintenance, and continued use is not effective to control flare-ups,” said lead researcher Jolanda Cibere.

The researchers studied 137 patients in four Canadian cities who had been using glucosamine for an average of two years and had credited it for at least a moderate improvement in their condition.

Glucosamine is derived from shellfish and is sold under several brand names as a health food supplement.

Cibere said some of the patients told her they planned to keep using the supplement even after hearing the results of the study, which was conducted in conjunction with the Arthritis Research Center in Vancouver.

“Some said, yes, they did stop it and felt no difference. Others said they did not want to stop and they truly believed in it regardless of the results,” she said.