Glucosamine for Knees -- Evidence Builds

Using the Right Dose of the Supplement, Patience Are Key to Effectiveness

Jan. 27, 2003 - Many people swear by the supplement glucosamine to help ease their arthritic knee pain. But only recently has scientific evidence been appearing to back it up. Now, a new study not only adds to that evidence, but also gives a better understanding of how long it takes for glucosamine to start working.

Glucosamine is a natural substance produced by the body and found primarily in joint cartilage, where it is thought to play an important role in maintaining joint health and resilience. Glucosamine supplements are widely sold in health food stores and over the Internet.

Previous studies have found at least some perceived benefit among users, but the results have been somewhat controversial. Many of these studies have been criticized for using too low a dose, short treatment periods, small numbers of participants, and a lack of tests to document actual changes in pain.

In this study, researchers say they attempted to overcome some of these shortcomings by looking at the effects of 12 weeks of glucosamine supplements at a dose of 2000 mg per day. In addition, they included tests to directly measure joint function and pain in people with knee pain.

The results appear in the February issue of the British Journal of Sports Medicine.

The size of the study was relatively small, involving only 24 people who took glucosamine and 22 who took a placebo. The patients ranged in age from 20 to 70 years and all suffered from knee pain due to previous cartilage damage or possibly osteoarthritis that was severe enough to limit daily activities.

Tests such as a stair climb and duck walk measured knee joint function and the participants also answered two questionnaires on perceived pain.

Researchers found that general mobility improved over time in both groups, but this improvement happened more quickly among those treated with glucosamine, starting after about four to eight weeks of treatment.

But the biggest benefits of glucosamine seemed to be in reducing the amount of perceived pain. By the end of the study, 88% of the glucosamine group said their knee pain had improved compared to only 17% in the placebo group -- even though the participants did not know which pill they were taking.

Researcher Rebecca Braham of the department of epidemiology and preventive medicine at Monash University in Prahran, Australia and colleagues say the results show that it takes at least four to eight weeks for the maximum benefits of glucosamine to appear. After four weeks of treatment, only 36% of users reported some pain relief, but that number grew to 68% at week eight and 88% by week 12.

SOURCE: British Journal of Sports Medicine, February 2003.