Is Glucosamine Effective for Treating Knee Osteoarthritis?

It's a controversial supplement, so keep these tidbits in mind

Glucosamine is a dietary supplement sometimes used to ease the pain of knee osteoarthritis (OA). Once quite popular, its use is now dwindling, mostly because of mixed results surrounding this supplement's true benefit.

If you take glucosamine or are considering a trial of the supplement (under the care of your doctor, of course) here are five tidbits to keep in mind:

The glucosamine supplement
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Tidbit #1: Glucosamine Is Naturally Found in Cartilage

Glucosamine is a natural substance (called an amino sugar) that is found in healthy articular cartilage and synovial fluid, both of which cushion your joints. In osteoarthritis, the articular cartilage in your joints deteriorates, causing pain and stiffness. The pain can be especially excruciating as the cartilage becomes so worn away that bones begin rubbing against each other.

Tidbit #2: Glucosamine Is Not Regulated as a Drug

In the United States, glucosamine is sold as a dietary supplement. This means that it's regulated by the United States Food and Drug Administration (FDA) as a food product, as opposed to a prescription or over-the-counter drug. 

With that, even though glucosamine is a natural component of cartilage, it does not mean that taking it is perfectly safe. In fact, glucosamine may alter blood sugar levels and may interact with some medications like the blood-thinner Coumadin (warfarin).

As always, be sure to only take a drug, including supplements, under the care of your personal physician. 

Tidbit #3: Glucosamine May Not Be Effective for Your Knee Osteoarthritis

While research studies on cartilage cells found that glucosamine can enhance the regrowth of cartilage and suppress inflammatory processes that lead to cartilage damage, this laboratory data has not translated into clinical benefit.

The first large study in the United States that examined the short-term effects of glucosamine (on knee osteoarthritis) was called the GAIT trial (Glucosamine Arthritis Intervention Trial).

 In GAIT, over 1500 participants with knee osteoarthritis were randomly assigned to one of five treatment groups:

  • Glucosamine at 500mg three times a day (total 1500mg per day)
  • Chondroitin sulfate (also a dietary supplement and a natural substance of cartilage) at 400mg three times a day (1200mg per day)
  • Glucosamine and chondroitin sulfate in combination
  • Celecoxib (a nonsteroidal anti-inflammatory, or NSAID) at 200mg daily
  • A placebo (a substance that is inactive) 

Results from the GAIT study showed that participants taking the NSAID celecoxib experienced statistically significant pain relief versus placebo.

There were no significant differences between the other treatments tested and placebo.

Although, in some of the study participants with moderate-to-severe pain, glucosamine combined with chondroitin sulfate provided significant pain relief when compared with placebo. Researchers of the study, however, said that because the size of this subgroup was so small, this finding should be considered preliminary and needs to be confirmed in future research studies.

For participants with mild knee pain (as opposed to moderate or severe) glucosamine and chondroitin sulfate together or alone did not provide significant pain relief.

Tidbit #4: There Are Two Types of Glucosamine

It's important to note that glucosamine can be given with two different types of salt, hydrochloride or sulfate. The GAIT study (mentioned above) used glucosamine hydrochloride. Interestingly, studies that have shown some potential, albeit small, used glucosamine sulfate to treat osteoarthritis instead of glucosamine hydrochloride.

For example, a large study in the International Journal of Clinical Practice analyzed over 3000 patients with knee osteoarthritis within 19 different trials. The authors of this study concluded that glucosamine hydrochloride was not beneficial in reducing pain (like the GAIT trial).

However, high doses of glucosamine sulfate (1500mg per day) may have function-modifying effects when taken for more than 6 months. Function-modifying effects mean that the glucosamine sulfate may improve a person's ability to use their knee (or knees) with osteoarthritis. 

Tidbit #5: What the American College of Rheumatology States About Glucosamine

According to the American College of Rheumatology, or ACR, people with knee osteoarthritis should not use glucosamine. However, this recommendation was made "conditionally," as the ACR recognizes that glucosamine use is still controversial. 

Instead, the ACR recommends the following for treating knee OA:

A Word From Verywell

While the promise of glucosamine as an alternative therapy for knee osteoarthritis has not exactly panned out, some people still take it and find it works for them.

In the end, regardless of your current treatment plan for your knee osteoarthritis, it's important to see your doctor for regular follow-up. This way you can modify your therapies as your joint health evolves and research unfolds.  

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