Are glucosamine and chondroitin effective in treating Osteoarthritis?
The published studies show conflicting results . Glucosamine sulfate (or hydrochloride) and chondroitin sulfate (so-called nutraceuticals) are classified as dietary supplements and as such are not regulated by the Food and Drug Administration (FDA). Consequently, compound amount, purity, long-term safety, and product labeling are not guaranteed. Absorption of both of these molecules varies greatly between individuals. Approximately 90% of glucosamine sulfate is initially absorbed, with half of that being removed by the liver. This leaves a bioavailable dose for distribution to joints of only 45%, with only half of this (i.e., 20%–25%) actually getting into the joint. Gastrointestinal absorption of chondroitin sulfate is even lower, with only 15% to 24% being bioavailable. Glucosamine is the principal component of glycosaminoglycans, which form the matrix of all connective tissue including cartilage. In vitro studies show that glucosamine is incorporated into and increases synthesis of proteoglycans by chondrocytes. Glucosamine may also have some mild antiinflammatory effects. In vitro , chondroitin sulfate has a tropism for cartilage and can stimulate proteoglycan synthesis and block certain proteases. Guidelines for patients who wish to take these medications are as follows:
- • Glucosamine sulfate is three times better absorbed than glucosamine hydrochloride. Results with glucosamine hydrochloride have been disappointing.
- • Dose of glucosamine is 1500 mg daily. It should be taken all at once and not in divided doses.
- • Dose of chondroitin sulfate is 1200 mg daily.
- • Symptomatic relief should be noted within 2 months if it is going to be effective.
- • Side effects are minimal. Patients with shellfish allergies may have a reaction to glucosamine. May increase warfarin effect.
