How does a glucosamine dietary supplement slow the progression of osteoarthritis?

Answer 1

There is no effective treatment for osteoarthritis (OA), a chronic degenerative joint disease that afflicts most people to some degree by the time they reach the age of 70. A wide range of options, however, are available to people looking for symptom relief. Most of the OA studies have concentrated on the hip and knee, the weight-bearing joints most likely to cause pain and disability.

Exercise:

People with knee OA can benefit from exercise, in terms of pain relief and improved function, according to a review of 17 studies conducted by the Cochrane Collaboration (see below). Of the combined total of 1,492 people who participated in the studies, those doing some form of exercise, be it walking or muscle-strengthening exercises, were better off than those who did not. However, the effect of exercise overall was found to be quite small. The reviewers did not find enough good quality studies to determine a benefit to people with hip OA.

After this Cochrane Review was completed, a newly published study called into question the standard thigh-muscle strengthening advice given to people with knee OA ( Annals of Internal Medicine , 4/15/03). It found that quadriceps muscle strengthening might actually be counterproductive to people whose knees are misaligned or unusually loose. Leena Sharma , MD, and colleagues at Northwestern University, Chicago, followed 230 people with knee arthritis who experienced difficulty with knee-related activities After 18 months the x-rays showed that OA progressed in the people with greater quadriceps muscle strength. Worsening of arthritis was defined as more joint space narrowing on knee x-rays. These results do not mean that exercise is bad for people with knee OA, only that the muscle-strengthening regimen for those with misaligned or loose knee joints might be reconsidered. This study did not assess the participants' symptoms.

Drugs:

In the March 2003 issue of Current Opinion in Rheumatology, Bischoff and Roos noted that exercise will provide a “small to moderate benefit” in terms of pain and improved function to people with hip and/or knee arthritis. And the “small to moderate benefit,” they wrote, also applies to the non-steroidal anti-inflammatory drugs (NSAIDs) commonly prescribed for osteoarthritis. NSAIDs encompass a wide range of popular over-the-counter and prescription drugs, including aspirin, Ibuprofen, Motrin, Naprosyn, Mobic, Celebrex, and Vioxx.

Acetaminophen (Tylenol) used to be singled out as the most effective OA drug, but a recent review found NSAIDs to be superior to acetaminophen in reducing pain and overall disease activity. The review conducted by the Cochrane Collaboration involved six randomized controlled trials; it also found NSAIDs were not better than acetaminophen in improving joint function. And there is no consistent evidence to show that any one NSAID stands out among the rest. A survey, published in 2000, found that most people take many different drugs for OA. The majority found a NSAID to be more “helpful” than acetaminophen, though many reported taking a NSAID and acetaminophen.

All NSAIDs and acetaminophen (in high doses) are associated with gastrointestinal bleeding which accounts for an estimated 70,000 hospitalizations and 10-15,000 deaths each year in the U.S. Only one in five people who develop this adverse reaction will have symptoms in advance. Gastrointestinal bleeding occurs in 1% of everyone who takes NSAIDs for three to six months, and in 2-4% of those taking NSAIDs for one year. The risk increases accordingly in those who take the drugs for longer periods of time.

The newest, most expensive NSAIDs—Celebrex, Vioxx, Bextra, which are from a drug class called COX-2 inhibitors—are no more effective as painkillers than other NSAIDs, though they may lower the risk of gastrointestinal reactions. The Food and Drug Administration (FDA) ruled that uncertainties remain about this advantage because many of the study participants in the pre-approval trials were not representative of the people who typically take NSAIDs. For example, 40% of the participants in the Celebrex studies had an endoscopic examination that ruled out the presence of ulcers prior to participation. Also, many of the study participants taking COX-2 inhibitors were also taking low doses of aspirin to prevent heart attacks, thereby reducing any stomach-protective benefit. Elderly people, particularly those who are debilitated, and those with ulcers should not take these drugs for OA, nor should anyone with heart disease.

Most NSAID studies pit a drug against a placebo and follow people only about 12 weeks. Some have compared a COX-2 inhibitor with another NSAID and have found their pain-relief benefit to be equivalent. In one Vioxx study, however, the people taking COX-2 inhibitors had twice the rate of heart attacks as those taking Naproxen.

Glucosamine:

Glucosamine is a natural substance classified by the FDA as a dietary supplement, which means that it is available over-the-counter without the safety and efficacy testing required of drugs. Furthermore, there is no quality control so consumers cannot count on the supplement containing the ingredients or the amount listed on the label. Studies conducted with glucosamine in standardized doses show that it is safer than OA drugs and just as effective in alleviating pain. Most intriguing, glucosamine appears to slow the progression of OA.

The Cochrane Collaboration reviewed 16 randomized, controlled trials ( RCTs ) and evaluated the effectiveness and safety of glucosamine for people with OA. In 13 RCTs in which glucosamine is compared to a placebo, glucosamine was found to be superior in all but one trial. In the four RCTs in which glucosamine was compared to a NSAID, glucosamine was found to be superior in two and equivalent in two. This review concluded that further research is needed to confirm the long-term effectiveness and safety of glucosamine. Few of the RCTs lasted more than six weeks. Glucosamine appears to be far safer than NSAIDs and acetaminophen—based on the mostly short-term results of these RCTs .

One RCT in this review found that the people taking a placebo showed a progressive joint-space narrowing that did not occur among those taking glucosamine. Symptoms worsened slightly in the placebo group, but the significant lessening of pain and disability was sustained for three years among those taking glucosamine.

Ultrasound, Electromagnetic Fields, etc.:

Electrical stimulation therapy had a small to moderate effect on knee OA, according to three studies with a total of 259 people who had been randomly assigned to this treatment or a placebo. Transcutaneous electrical nerve stimulation, also known as TENS, was shown in seven trials to provide significant improvement in knee stiffness and pain relief. Ultrasound therapy had no benefit over placebo or short wave diathermy in three clinical trials.

Herbal Medicine

The Cochrane Collaboration conducted a review of the evidence for herbs and plant substances and found two studies that showed avocado/soybean oil extract had beneficial effects on joint function, pain, and reduced need for NSAIDs, and general well-being. The symptomatic relief persisted even after discontinuation. Results were better with hips than knees. The former involves more chronic and continuous inflammation and pain, whereas the latter is more likely to consist of flare-ups. Avocado/soybean extract is sold as a dietary supplement in the U.S. under the brand name of AvoFlex .

Rub-on Creams

Rubbing liniment, such as capsaicin cream, into the skin around the joint will stimulate blood flow and create warmth, which may temporarily reduce pain and improve function.

What is the Cochrane Collaboration?

The Cochrane Collaboration is an international network of over 6,000 researchers, epidemiologists, physicians, consumer advocates, scientists, and statisticians in over 60 countries. Most are based at universities and medical centers. Their work is divided into review groups, according to topic (e.g., breast cancer, pregnancy and childbirth, complementary medicine).

Each review group conducts systematic reviews of all available research on a specific treatment, such as “Glucosamine Therapy for Treating Osteoarthritis.” The goal is to help doctors and consumers make informed decisions by answering the question: Is there high-quality evidence to show that this treatment is effective and safe?

Most of the information in this article came from the Musculoskeletal Review Group whose Web site (www.cochranemsk.org) offers free access to summaries (abstracts) of existing reviews intended for health professionals. For more consumer friendly summaries, go to www.cochraneconsumer.com to read Cochrane abstracts on a range of medical topics.

Answer 2

They say it replaces the glucosamine and chondroitin in the joints. But if you read the leaflets or bottle inscriptions on some of these products, it is written "No approved therapeutic claims". So it may or may not work.

Answer 3

i really don't know but I know the stuff works. If you take a healthy dose 2 times a day for a month it does wonders.What i have read, half snake oil salesmen and half medical stuff says that the stuff comes From shark cartilage etc, and your body uses it to replace buggered up joint tissue. They also said that eventually you have to go to more serious treatments but it is a good first line therapy until it quits working,

Answer 4

1

Answer 5

It certainly helped my pain. I take Osteo BiFlex.