Herbs & Supplements:
Glucosamine

Supplement Forms / Alternate Names
  • Glucosamine Sulfate, Glucosamine Hydrochloride, N-Acetyl Glucosamine
Principal Proposed Uses
  • Osteoarthritis (Relieving Symptoms and Slowing the Course of the Disease)
Other Proposed Uses
  • Tendinitis, Muscle Injury Prevention

Glucosamine, most commonly used in the form glucosamine sulfate, is a simple molecule derived from glucose, the principal sugar found in blood. In glucosamine, one oxygen atom in glucose is replaced by a nitrogen atom. The chemical term for this modified form of glucose is amino sugar.

Glucosamine is produced naturally in the body, where it is a key building block for making cartilage. In Europe, glucosamine is widely used to treat osteoarthritis. Studies show that glucosamine supplements relieve pain and other arthritis symptoms. Interestingly, these improvements seem to last for several weeks after glucosamine supplements are discontinued.

This observation has led to the exciting idea that glucosamine may actually make a deep change in osteoarthritis, rather than simply relieving symptoms. Conventional treatments for arthritis reduce the symptoms but don't slow the actual progress of the disease; in fact, nonsteroidal anti-inflammatory drugs, such as indomethacin, may actually speed the progression of osteoarthritis by interfering with cartilage repair and promoting cartilage destruction.^1–5

In contrast, glucosamine might go beyond treating the symptoms to actually slowing the disease itself. (Chondroitin sulfate and SAMe may do the same.) If this is true, it would represent a revolutionary breakthrough in the treatment of arthritis. However, the evidence for such a “disease-modifying effect” is not yet definitive.

Some athletes use glucosamine, in the (unproved) belief that it can prevent muscle injuries, relieve tendinitis, and repair damaged cartilage.

Sources

There is no U.S. Dietary Reference Intake (formerly known as the Recommended Dietary Allowance) for glucosamine. Your body makes all the glucosamine it needs from building blocks found in foods.

Glucosamine is not usually obtained directly from food. Glucosamine supplements are derived from chitin, a substance found in the shells of shrimp, lobsters, and crabs.

Therapeutic Dosages

For osteoarthritis, a typical dosage of glucosamine is 500 mg 3 times daily. A 1,500-mg dose taken once daily may also be effective.⁶ Be patient: results take weeks to develop. Glucosamine is available in three forms: glucosamine sulfate, glucosamine hydrochloride, and N-acetyl glucosamine. All three forms are sold as tablets or capsules. There is some dispute over which form is best.

Glucosamine is often sold in combination with chondroitin. Preliminary information from animal studies suggests that this mixture may be superior to either treatment alone.^7,8

Therapeutic Uses

Glucosamine is used to treat osteoarthritis. Taken as a whole, the research indicates that it is effective, and about equal in strength to nonsteroidal anti-inflammatory drugs such as ibuprofen.^{9–14,23,24,41} It reduces pain and swelling and improves mobility with results that continue for weeks after treatment stops. It also might help prevent progressive joint damage, thereby slowing the course of the disease.¹⁵

We don't know exactly how glucosamine works. However, besides serving as a basic building block for cartilage, glucosamine appears to stimulate cartilage cells in your joints to make proteoglycans and collagen, two proteins essential for the proper function of joints.^28–32 Glucosamine may also help prevent collagen from breaking down.³³

Glucosamine has been proposed to treat tendinitis, to prevent muscle injuries, and to repair damaged cartilage, but there is as yet no evidence that it is effective.

What Is the Scientific Evidence for Glucosamine?

Osteoarthritis

Symptom Relief

Reasonably good evidence indicates that glucosamine supplements effectively relieve pain and other symptoms of osteoarthritis. Two types of studies have been performed, those that compared glucosamine against placebo and those that compared it against standard medications.

One double-blind study compared glucosamine sulfate against placebo in 252 people with osteoarthritis of the knee.¹⁶ After 4 weeks, the group that was given glucosamine experienced significantly reduced pain and improved movement, to a greater extent than the improvements seen in the placebo group.

Another double-blind study divided 329 people into four groups.^17,18 One group was given the standard antiarthritis drug piroxicam (Feldene), a second was given glucosamine, a third received both treatments, and the fourth received placebo only. Over 90 days, piroxicam and glucosamine proved equally effective at reducing symptoms. Interestingly, the combination treatment (piroxicam plus glucosamine) didn't produce significantly better results than either treatment taken alone.

After 90 days, treatment was stopped and the participants were followed for an additional 60 days. The benefits of piroxicam rapidly disappeared, but the benefits of glucosamine lasted for the full 60 days.

Similar results have been seen in studies that compared glucosamine against ibuprofen for knee arthritis as well as temporomandibular joint (TMJ) arthritis.^19,20,21

In addition, a 6-month, double-blind, placebo-controlled study of combined glucosamine, chondroitin and manganese found evidence of significant improvement in the treated group.²²

However, not all studies found benefit. In three studies involving a total of almost 300 individuals, use of glucosamine failed to provide any improvement in symptoms.^23,24,41 The explanation for this discrepancy is not clear. The authors of two of these trials suggest as a possible explanation that glucosamine might be most effective in relatively mild cases of arthritis; the participants in their studies had relatively severe arthritis.^23,41 Further investigation will be necessary to determine if this hypothesis is correct.

Slowing the Course of the Disease

A 3-year, double-blind, placebo-controlled study of 212 individuals found that glucosamine can protect joints from further damage.²⁵ Over the course of the study, individuals given glucosamine showed some actual improvement in pain and mobility, while those given placebo worsened steadily. Perhaps even more importantly, x-rays showed that glucosamine treatment prevented progressive damage to the knee joint. However, the form of x-ray evaluation used in this study is not considered completely reliable as a means of detecting the overall level of joint deterioration; for this reason, this study cannot be regarded as proving that glucosamine has a disease-modifying effect.

Safety Issues

Glucosamine appears to be a generally safe treatment, and has not been associated with significant side effects. This gives it a substantial potential advantage over standard drug treatment, which can cause ulcers. However, recent case reports and animal studies have raised concerns that glucosamine might be harmful for individuals with diabetes. It may raise blood sugar levels^34–39 and also increase the risk of long-term diabetes side effects such as cataracts.⁴⁰

Last reviewed June 2002 by Medical Review Board

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