Glucosamine and chondroitin have been touted as remedies for osteoarthritis …but do they really work?
What Are Glucosamine & Chondrotin?
Glucosamine and chondroitin are natural components of cartilage.
Glucosamine is an amino sugar that is the building block for glycoaminoglycans, which are part of the structural component of cartilage. It is crucial for the formation of hyaluronic acid, chondroitin sulfate and keratan sulfate, that are the main components of joint cartilage. In the body, glucosamine is synthesized from glucose. In supplement form, glucosamine is extracted from chitin, found in shellfish.
Chondroitin is a gel-forming complex carbohydrate. It has the capacity to attract and retain water in the cartilage, which is important for pressure resistance. Chondroitin in supplement form is extracted from animal cartilage.
Glucosamine & Chondrotin For Osteoarthritis: What Does The Science Say?
The efficacy of glucosamine and chondroitin for arthritis is in doubt as results from clinical trials are conflicting. Some small trials found moderate to large benefits of glucosamine and chondroitin in some people while large scale trials found little or no benefit at all.
A 2010 meta-analysis1 of 10 large scale trials in 3803 patients with knee or hip osteoarthritis found that glucosamine, chondroitin or in combination produced no clinically relevant effect on joint pain or on joint space narrowing, compared with placebo. In other words, they were no better than placebo.
Glucosamine/chondroitin Arthritis Intervention Trial (GAIT)2
Due to conflicting results from previous clinical trials, the Glucosamine/chondroitin Arthritis Intervention Trial (GAIT) was carried out to test the effects of glucosamine and chondroitin for treatment of knee osteoarthritis. GAIT is a large scale, multicenter clinical trial conducted at several sites in the United States.
There are 2 types of studies in GAIT: – a primary study to evaluate the efficacy and safety of glucosamine and/or chondroitin as a treatment for knee pain from osteoarthritis. – an ancillary study to evaluate whether the supplements could reduce the structural damage of osteoarthritis.
Participants were randomly assigned to receive one of the following five treatments daily:
- glucosamine hydrochloride alone (1,500mg),
- chondroitin sulfate alone (1,200mg),
- combination of glucosamine (1,500 mg) and chondroitin (1,200 mg),
- celecoxib (200 mg), or
- a placebo.
The first phase of GAIT is the primary study to test the effectiveness of glucosamine and chondroitin for 6 months (short term).
It was found that glucosamine and chondroitin did not provide significant relief from osteoarthritis pain among all participants. However, a smaller subgroup of participants with moderate to severe pain showed significant relief with the combined glucosamine and chondroitin compared to placebo. Surprisingly, glucosamine and chondroitin, together or alone, did not provide significant pain relief for participants in the mild pain subgroup. Due to the small number of participants in the moderate to severe pain subgroup, the researchers cautioned that the findings this subgroup were preliminary and needed to be confirmed in further studies.
The second phase of GAIT is the ancillary study to investigate whether glucosamine and chondroitin could reduce structural damage from osteoarthritis of the knee. This study enrolled interested participants from the phase 1 study for an additional 18 months (2 years in total).
Loss of cartilage is a key feature of osteoarthritis and this is measured by reduction in joint space width in this study. Hence, loss of joint space width is a marker for the extent of structural (cartilage) damage.
(Image Credit: National Institute of Arthritis and Musculoskeletal and Skin Diseases (NIAMS))
At the end of this study, there was no statistically significant difference in joint space width loss for any treatment group compared to the placebo group. Glucosamine, chondroitin and in combination were no better than placebo in slowing loss of cartilage in osteoarthritis of the knee.
Due to the lack of long term studies, the third phase of GAIT was undertaken to evaluate the safety and efficacy of the supplements for two years. Over the 2-year period, all the treatment groups experienced improvement in pain and function but no treatment was significantly better than placebo.
New Study3 On Glucosamine& Chondroitin For Treatment of Knee Osteoarthritis (Published in December 2016)
The latest study assessed the efficacy and safety of combination of glucosamine and chondroitin vs. placebo for treatment of knee osteoarthritis. 164 patients were randomised to receive either glucosamine sulfate (1,500 mg) plus chondroitin sulfate (1,200 mg) or placebo daily for 6 months.
Interestingly, there was greater improvement in pain in the placebo group compared to the glucosamine plus chondrotin group. This study results show a lack of superiority of glucosamine plus chondroitin treatment over placebo in reducing joint pain and functional impairment in patients with knee osteoarthritis after 6 months.
Bottom Line – Should You Take Glucosamine And Chondrotin For Osteoarthritis?
The majority of the published clinical trials show that glucosamine and chondrotin are ineffective treatment for knee osteoarthritis. Yet, some people are convinced of their perceived benefits whether due to the placebo effect or for unknown reasons.
Studies have shown that both supplements are considered safe for long term use, without serious side effects.
Before taking these supplements, check with your doctor whether they are an appropriate treatment option and for possible interactions with your current medications. If you have shellfish allergy, be aware that glucosamine is extracted from chitin, which is found in shellfish, and could cause allergic reactions. Should you find no beneficial effect after taking them for a certain amount of time, then you should discontinue them.
1. Effects of glucosamine, chondroitin, or placebo in patients with osteoarthritis of hip or knee: network meta-analysis. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2941572/
2. GAIT. https://nccih.nih.gov/research/results/gait
3. Combined Treatment With Chondroitin Sulfate and Glucosamine Sulfate Shows No Superiority Over Placebo for Reduction of Joint Pain and Functional Impairment in Patients With Knee Osteoarthritis: A Six-Month Multicenter, Randomized, Double-Blind, Placebo-Controlled Clinical Trial. http://onlinelibrary.wiley.com/doi/10.1002/art.39819/abstract