Chondroitin Sulfate and Sulfur Containing Chondroprotective Agents: Is there a Basis for their Pharmacological Action?

Chondroitin sulfate, glucosamine sulfate and other sulfur containing compounds are widely used by individuals afflicted with joint pains. In spite of their incremental use, neither their efficacy nor their mode of action has been defined. Metabolic studies indicate that these compounds are degraded prior to absorption or shortly thereafter into their fundamental constituents: simple carbohydrates and inorganic sulfate. Polysaccharides cannot be reutilized as such, and inorganic sulfate can only be incorporated into cartilage glycosaminoglycans (GAG) following de novo activation. The carbohydrate moiety of GAG can, under normal circumstances, be readily synthesized by cells. If these compounds, rich in sulfur, are exhibiting any pharmacological effects, they are most likely doing so solely because of their ability to contribute this important element to our organism. Sulfur is normally derived from methionine and cysteine in proteins. Very little is derived from other dietary sources. The minimal daily requirements for this important mineral have never been established in spite that in addition to being essential for GAG synthesis, it is a structural component of glutathione and other key enzymes, coenzymes and metabolites that play fundamental roles in cellular homeostasis and control of inflammation. It is therefore not unlikely that any beneficial effect of these dietary supplements results from their ability to supplement our diet with a source of inorganic sulfur.