What are glucosamine (G) and chondroitin sulfate (CS) and what do they do?

Glucosamine and chondroitin sulfate are building blocks that the body uses to form a variety of soft tissue structural elements. One such essential structure is the cartilage that is found in joints (e.g., knee joint). The functions of articular (joint) cartilage, which covers the ends of the bones that form the joint, are to provide near frictionless motion, and to act as a shock absorber. Just like other systems and structures in the body, disease or disability can result from breakdown or poor function. Osteoarthritis (OA), the most common type of joint disorder, occurs when the articular cartilage in a given joint thins and wears away.

Several years ago G and CS became popular as "natural" alternatives to anti-inflammatory medications to help relieve the pain associated with OA.

Do glucosamine and chondroitin sulfate relieve pain?

Irrespective of pain relieving qualities do glucosamine and chondroitin sulfate cause the body to regenerate damaged cartilage and thus reverse the destructive process of OA?


Searching for the answer to the first question has been the driving force behind several clinical experiments, and the results are mixed. A recent medical journal article (1) looked closely at all of the published evidence about G and CS in an attempt to reach some sort of consensus. The conclusion was that these substances probably do have some effect in alleviating the pain of OA, but the claims are likely exaggerated. Especially by those profiting from their sale. At this point in time, no one knows how G and CS might exert this pain relieving property. One thing is certain G and CS are very popular dietary "supplements".

Despite the pain relieving properties there is, however, no data to support the idea that G and CS help grow cartilage. In other words, whatever mechanism is responsible for reducing some of the pain in OA it is not because G and CS are repairing or building articular cartilage. People taking these supplements for long periods of time may experience some pain relief, but anatomically the damaged cartilage doesn’t change. The idea that eating components of cartilage would help grow cartilage in the exact area you need it is, to quote one famous orthopedist, "like eating hair to help fill in the bald spots on your head".

What about runners; Should they take these supplements to help with injuries?
This question has not yet been addressed in any study. Everything to this point has addressed patients with documented OA. However, given the popularity of G and CS it is likely that some runners have considered, or are, using these supplements in an attempt to treat injuries. To reiterate there is nothing to support the use of G and/or CS to treat or prevent running related injuries. Following a similar train of thought, there is no data suggesting that regular use of G and CS will prevent OA. [As an interesting side note: despite popular opinion to the contrary, distance running does not appear to a risk factor for the development of OA. So enjoy those miles!]

So the bottom line is that those with OA should consult with their doctor about G and CS. Runners hoping to prevent or treat injury should probably save their money, or spend it elsewhere. Finally, no long term investigation into the safety of G or CS have been done.