Q. Are glucosamine and chondroitin good for arthritis?

Arthritis is inflammation of the joints. Osteoarthritis is the most prevalent form of the condition. An estimated 27 million adults in the United States live with osteoarthritis.

You get osteoarthritis when cartilage — the cushioning tissue within the joints — wears down. The disease affects both men and women. By age 65, more than 50 percent of us have osteoarthritis in at least one joint.

Osteoarthritis can affect any joint, but it usually strikes those that support weight. Common signs of osteoarthritis include joint pain, swelling, and tenderness.

Treatments for osteoarthritis include exercise, joint care, dieting, medicines and surgery. For pain relief, doctors usually start with acetaminophen, the medicine in Tylenol, because the side effects are minimal. If acetaminophen does not relieve pain, then non-steroidal anti-inflammatory drugs (NSAIDS) such as ibuprofen (Advil) and naproxen (Aleve) may be used.

Many people say glucosamine and chondroitin can relieve the symptoms of osteoarthritis. In the United States, glucosamine and chondroitin are sold as dietary supplements, which are regulated as foods rather than drugs. The annual sales of the supplements around the world are about $2 billion.

Glucosamine and chondroitin are two molecules in joint cartilage. Treatment with these supplements is based on the theory that consuming them may speed the formation of new cartilage. There is no proof that glucosamine and chondroitin help form new cartilage.

However, there are studies indicating that the supplements relieve pain better than placebos. The pain reduction found in these studies was similar to results obtained by NSAIDs. However, NSAIDS have side effects including gastrointestinal bleeding. Glucosamine and chondroitin have few side effects.

While there are indications that glucosamine and chondroitin have pain-relieving qualities, the supplements have yet to pass a test that would qualify them to be a primary treatment for osteoarthritis. More research is needed.

In one study, the combination of glucosamine and chondroitin did not provide significant relief from osteoarthritis pain among all participants. A total of 1,583 people with an average age of 59 participated in the study.

However, for a subset of participants with moderate-to-severe pain, glucosamine combined with chondroitin provided statistically significant pain relief compared with placebo. About 79 percent had a 20 percent or greater reduction in pain compared to about 54 percent for placebo. Researchers said these findings need to be confirmed in further studies because of the small size of this subgroup.

This research was funded by the National Institutes of Health. Researchers led by rheumatologist Daniel O. Clegg, M.D., of the University of Utah, School of Medicine, conducted the 4-year study known as the Glucosamine/chondroitin Arthritis Intervention Trial (GAIT) at 16 sites across the United States.

The GAIT study included an additional inquiry to investigate whether these supplements could diminish structural damage from osteoarthritis of the knee. At the end of the ancillary study, the team had gathered data on 581 knees. After assessing the data, the researchers concluded that glucosamine and chondroitin appeared to do no better than placebo in slowing loss of cartilage in osteoarthritis of the knee.

Another important study was done by Dr. Peter Juni of the University of Toronto, and Dr. Andrew Sherman at the University of Miami.

For the study, the investigators analyzed the results of 10 randomized clinical trials involving more than 3,800 patients with knee or hip osteoarthritis. They found no clinically relevant effect of chondroitin, glucosamine or both taken together on joint pain.

“We need to look more closely at these over-the-counter medications that claim to be panaceas and may not be giving us our money’s worth,” Dr. Sherman said.

Should you try the supplements? Not without consulting your personal physician.