Glucosamine and chondroitin are part of normal cartilage. Cartilage acts as a cushion between the bones in a joint.
How do glucosamine and chondroitin work?
Glucosamine and chondroitin are two molecules that make up the type of cartilage found within joints. Inside your joints, cartilage undergoes a constant process of breakdown and repair. However, to be properly repaired, the building blocks of cartilage must be present and available. The theory behind using the glucosamine and chondroitin joint supplements is that more of the cartilage building blocks will be available for cartilage repair.
Glucosamine is a precursor to a molecule called a glycosaminoglycan-this molecule is used in the formation and repair of cartilage.
Chondroitin is the most abundant glycosaminoglycan in cartilage and is responsible for the resiliency of cartilage.
Treatment with these joint supplements is based on the theory that oral consumption of glucosamine and chondroitin may increase the rate of formation of new cartilage by providing more of the necessary building blocks.
How do these supplements help arthritis?
It is believed these supplements may be useful for people with osteoarthritis (OA), where there has been a breakdown of cartilage. It is thought that taking glucosamine and/or chondroitin supplements may relieve the pain and prevent or slow the breakdown of cartilage in OA. Note, most of the studies have looked only at OA of the knee, with very few studies of other joints (for example, hips, hands, back). To date there is no evidence that these supplements are effective for any other forms of arthritis.
What is the recommended dose?
Glucosamine sulfate: 1500mg per day
Glucosamine hydrochloride: 1500mg per day (note, glucosamine sulfate is suggested to be more effective)
Chondroitin sulfate: 800 - 1000mg per day
Different brands contain different amounts of glucosamine and chondroitin. Read the label carefully to see how many tablets you need to take to get the right dose or ask your pharmacist for advice.
How long will it take to notice an effect?
You may need to take the supplements for four to six weeks before you notice any improvement. If there is no change in your symptoms by then, it's likely the supplements will not be of benefit for you and it's advisable you talk to your doctor about other ways of managing your arthritis.
What are the possible risks?
Shellfish allergies: glucosamine is often made from shellfish so you should talk to your doctor before taking glucosamine if you are allergic to shellfish.
Bleeding: people taking the blood thinning medicine warfarin should talk to their doctor before starting, stopping or changing their dose of glucosamine as it may interact with warfarin and make the blood less likely to clot.
Diabetes: glucosamine is a type of sugar so check with your doctor before taking glucosamine if you have diabetes.
Pregnant or breastfeeding women: there have not been enough long term studies to clearly say that glucosamine is safe for a developing baby. Pregnant women should talk to their doctor before taking glucosamine.
Other side effects: upset stomach (for example, diarrhoea), headaches, and skin reactions. Talk to your doctor or pharmacist about possible side effects before taking glucosamine.
Bleeding: people taking blood thinning medicines, such as warfarin, should talk to their doctor before taking chondroitin as it may increase the risk of bleeding.
Other side effects: chondroitin may also occasionally cause stomach upsets.