Popular dietary supplements – glucosamine and chondroitin sulfate – proved no better than placebos in treating people suffering from osteoarthritis, a two years study published in the journal Arthritis & Rheumatism revealed.

The study is a follow-up to a large 2006 National Institutes of Health-funded study, which was designed to look whether supplements did a better job than sugar pills or the arthritis pain medication Celebrex in reducing pain in osteoarthritis patients. But the study found no improvement in those given supplements. The study was called GAIT (Glucosamine/chondroitin Arthritis Intervention Trial) and was published in the New England Journal of Medicine in 2006.

At the end of the study, the researchers continued to watch 572 volunteers for another 18 months and found the supplements did not appear to slow the loss of cartilage, taken either alone or together. More exactly, arthritis worsened in 24 percent of participants taking both, similar to those taking placebo.

“We don’t have good evidence that it (glucosamine and chondroitin sulfate combination) slows (disease) progression,” rheumatologist Allen Sawitzke, professor of internal medicine at the University of Utah and head investigator, said.

The study comes like a slap in the face of supplements’ makers. The combination glucosamine – chondroitin sulfate is the sixth-top-selling dietary supplement in the United States, with annual sales of $831 million last year, according to the “Nutrition Business Journal.”

However, Dr. Sawitzke said he would neither encourage nor discourage patients from taking the supplements.

"We didn't run into safety issues, so if a patient wants to try them, I don't see a reason to say no. But I can't recommend it; there's no supportive data that says it works," he said.

According to the most recent figures made public by the Arthritis Foundation, osteoarthritis, the most common form of arthritis, currently affects 27 million of the 46 million people in the United States with arthritis. In addition, one in two Americans are at risk for knee osteoarthritis over their lifetime.

Osteoarthritis (OA), also called osteoarthroses or degenerative joint disease, is the most common type of arthritis. OA is a chronic condition characterized by the breakdown of the joint’s cartilage. Cartilage is the part of the joint that cushions the ends of the bones and allows easy movement of joints. The breakdown of cartilage causes the bones to rub against each other, causing stiffness, pain and loss of movement in the joint. OA typically affects only certain joints, such as the hips, hands, knees, low back and neck. After the age of 50, women are more often affected by OA than men. There are not known cause of OA but certain factors such as heredity, overweight, joint injury, repeated overuse of certain joints, lack of physical activity, nerve injury and aging increase the risk of developing OA.

Arthritis and related conditions, such as OA, cost the U.S. economy nearly $128 billion per year in medical care and indirect expenses, including lost wages and productivity.